Efficacy and acceptability of very low energy diets in overweight and obese people with Type 2 diabetes mellitus: a systematic review with meta-analyses

The NHS Low-Calorie Diet Digital Programme: Fidelity of behaviour change technique delivery

AIMS

NHS England commissioned independent service providers to deliver the NHS Low-Calorie Diet Programme pilot. Previous research has illustrated a drift in the fidelity of behaviour change techniques (BCTs) during the delivery of the programme provided through face-to-face group or one-to-one behavioural support. The aim of this study was to assess the delivery fidelity of the BCT content in the digital delivery of the programme.

METHODS

Online, app chat and phone call support content was coded using The Behaviour Change Technique Taxonomy. BCTs delivered by each service provider (N = 2) were calculated and compared to the BCTs specified in the NHS service specification and those specified in the providers' programme plans.

RESULTS

Between 78% and 83% of the BCTs identified in the NHS service specification were delivered by the service providers. The fidelity of BCT delivery to those specified in providers' programme plans was 60%-65% for provider A, and 82% for provider B.

CONCLUSIONS

The BCT content of the digital model used in the NHS-LCD programme adhered well to the NHS service specification and providers' plans. It surpassed what has been previously observed in face-to-face services provided through group or one-on-one behavioural support models.

Preoperative dietitian-led Very Low Calorie Diet (VLCD) Clinic for adults living with obesity undergoing gynaecology, laparoscopic cholecystectomy and hernia repair procedures: a pilot parallel randomised controlled trial

Obesity can increase the risk of postoperative complications. Despite increased demand for patients living with obesity to lose weight prior to common surgical procedures, the impact of intentional weight loss on surgical outcomes is largely unknown. We aimed to conduct a pilot study to assess the feasibility of a full-scale randomised controlled trial (RCT) to examine the effect of preoperative dietitian-led Very Low Calorie Diet (VLCD) Clinic on surgical outcomes in gynaecology and general surgeries. Between August 2021 and January 2023, a convenience sample of adults living with obesity (BMI ≥ 30 kg/m2) awaiting gynaecology, laparoscopic cholecystectomy and ventral hernia repair procedures were randomised to dietitian-led VLCD (800-1000 kcal using meal replacements and allowed foods), or control (no dietary intervention), 2-12 weeks preoperatively. Primary outcome was feasibility (recruitment, adherence, safety, attendance, acceptability and quality of life (QoL)). Secondary outcomes were anthropometry and 30-d postoperative outcomes. Outcomes were analysed as intention-to-treat. Fifty-one participants were recruited (n 23 VLCD, n 28 control), mean 48 (sd 13) years, 86 % female, and mean BMI 35·8 (sd 4·6) kg/m2. Recruitment was disrupted by COVID-19, but other thresholds for feasibility were met for VLCD group: high adherence without unfavourable body composition change, high acceptability, improved pre/post QoL (22·1 ± 15 points, < 0·001), with greater reductions in weight (-5·5 kg VLCD v. -0·9 kg control, P < 0·05) waist circumference (-6·6 cm VLCD v. +0·6 control, P < 0·05) and fewer 30-d complications (n 4/21) than controls (n 8/22) (P > 0·05). The RCT study design was deemed feasible in a public hospital setting. The dietitian-led VLCD resulted in significant weight loss and waist circumference reduction compared with a control group, without unfavourable body composition change and improved QoL.

Acceptability, Adherence, Safety and Experiences of Low Energy Diets in People With Obesity and Chronic Kidney Disease: A Mixed Methods Study

OBJECTIVES

Obesity is a modifiable risk factor for chronic kidney disease (CKD) progression. Low energy diets (LEDs) have not been adequately studied in people with CKD. This study aimed to explore acceptability, adherence, safety, and experiences of two LED prescriptions in adults living with obesity and CKD.

DESIGN AND METHODS

In a mixed-methods study, obese adults with CKD were prescribed two LEDs (∼800 to 1000 kcal/day each), in a randomised order for 2 weeks each. One diet consisted of four meal replacement products daily (Optifast®, Nestlé Health Science) and the other two pre-prepared frozen meals (Lite n' Easy®, Mitchell's Quality Foods). Participants received weekly dietitian support, completed daily adherence checklists (converted to % of provided meals/replacements consumed) and participated in post-intervention semi-structured interviews to capture their experience.

RESULTS

Nine participants were included (mean age 46.5 ± 14.3 years, estimated glomerular filtration rate 64 ± 26 mL/min/1.73 m2, 4/9 male). Mean self-reported adherence was 88 ± 11% and mean 4-week weight change was -7.3 ± 5.6 kg. Two participants withdrew at week two. Most frequently reported side effects were hunger and headaches. Adverse events of interest included one episode each of hyperkalaemia and hypoglycaemia. No serious adverse events occurred. Four overarching themes of patient experiences were identified: strategies used to adapt, disruption to the norm, individual preferences, and influences on acceptability.

CONCLUSIONS

LEDs were found to be acceptable and safe with high self-reported adherence rates. Future LED trials should include specialist diabetes management, close monitoring for hyperkalaemia and adequate support to assist with managing side effects and dietary and social adjustments.

Normalisation and equity of referral to the NHS Low Calorie Diet programme pilot; a qualitative evaluation of the experiences of health care staff

BACKGROUND

Health and wellbeing can be profoundly impacted by both obesity and type 2 diabetes, while the normalisation and equity of care for people living with these non-communicable diseases remain as challenges for local health systems. The National Health Service Low Calorie Diet programme in England, aims to support people to achieve type 2 diabetes remission, while also reducing health inequalities. We have explored the experiences of health care staff who have made a referral to the LCD programme, while identifying effective and equitable delivery of programme referrals, and their normalisation into routine care.

METHODS

Nineteen individual semi-structured interviews were completed health care staff in the first year of the Low Calorie Diet programme. Interviewees were purposively sampled from the ten localities who undertook the Low Calorie Diet programme pilot. Each interview explored a number of topics of interest including communication and training, referrals, equity, and demands on primary care, before being subjected to a thematic analysis.

RESULTS

From the data, five core themes were identified: Covid-19 and the demands on primary care, the expertise and knowledge of referrers, patient identification and the referral process, barriers to referrals and who gets referred to the NHS LCD programme. Our findings demonstrate the variation in the real world settings of a national diabetes programme. It highlights the challenge of COVID-19 for health care staff, whereby the increased workload of referrals occurred at a time when capacity was curtailed. We have also identified several barriers to referral and have shown that referrals had not yet been normalised into routine care at the point of data collection. We also raise issues of equity in the referral process, as not all eligible people are informed about the programme.

CONCLUSIONS

Referral generation had not yet been consistently normalised into routine care, yet our findings suggest that the LCD programme runs the risk of normalising an inequitable referral process. Inequalities remain a significant challenge, and the adoption of an equitable referral process, normalised at a service delivery level, has the capacity to contribute to the improvement of health inequalities.

Commercial provider staff experiences of the NHS low calorie diet programme pilot: a qualitative exploration of key barriers and facilitators

BACKGROUND

The National Health Service Type 2 Diabetes Path to Remission programme in England (known as the NHS Low Calorie Diet programme when piloted) was established to support people living with excess weight and Type 2 Diabetes to lose weight and improve their glycaemic control. A mixed method evaluation was commissioned to provide an enhanced understanding of the long-term cost effectiveness of the pilot programme, its implementation, equity and transferability across broad and diverse populations. This study provided key insights on implementation and equity from the service providers' perspective.

METHODS

Thirteen focus groups were conducted with commercial providers of the programme, during the initial pilot rollout. Participants were purposively sampled across all provider organisations and staff roles involved in implementing and delivering the programme. Normalisation Process Theory (NPT) was used to design the topic schedule, with the addition of topics on equity and person-centredness. Data were thematically analysed using NPT constructs with additional inductively created codes. Codes were summarised, and analytical themes generated.

RESULTS

The programme was found to fulfil the requirements for normalisation from the providers' perspective. However, barriers were identified in engaging GP practices and receiving sufficient referrals, as well as supporting service users through challenges to remain compliant. There was variation in communication and training between provider sites. Areas for learning and improvement included adapting systems and processes and closing the gap where needs of service users are not fully met.

CONCLUSIONS

The evaluation of the pilot programme demonstrated that it was workable when supported by effective primary care engagement, comprehensive training, and effective internal and external communication. However, limitations were identified in relation to programme specifications e.g. eligibility criteria, service specification and local commissioning decisions e.g. pattern of roll out, incentivisation of general practice. A person-centred approach to care is fundamental and should include cultural adaptation(s), and the assessment and signposting to additional support and services where required.

Psycho-social factors associated with type two diabetes remission through lifestyle intervention: A scoping review

OBJECTIVES

There is growing evidence that type 2 diabetes (T2D) can be put into remission through lifestyle intervention. Current focus on remission in terms of physiological considerations and biomedical scales, means there is limited understanding of the role psycho-social factors play in moderating the efficacy of lifestyle interventions for T2D remission. In the current review we aimed to synthesise the emerging literature on psycho-social factors associated with T2D remission, specifically from lifestyle interventions.

METHODS

Five databases (EMBASE, MEDLINE, CINAHL ultimate, PsychINFO and PsycArticles) were searched to identify studies from 2009 onwards that reported remission outcomes from lifestyle interventions in participants ≥ 18years old, with a clinical diagnosis of T2D. Studies included were of an interventional or observational design and restricted to English language. Screening and data extraction was performed independently by two reviewers using prespecified criteria.

RESULTS

In total 6106 studies were screened, 36 studies meeting the inclusion criteria were included. Studies were globally diverse, with 30 (83%) being published ≥ 2017. Psycho-social scales were under-utilised with 22 (67%) of studies failing to include any psycho-social measures. Single arm, prospective studies were most frequently utilised, however study quality was perceived to be heterogeneous. Further disparity in the quality, content and delineation of the psycho-social interventions was also identified. Education and self-monitoring interventions were the most frequently incorporated. Self-monitoring was also identified as an important facilitator to remission, in addition to social support.

CONCLUSIONS

Our findings indicate that psycho-social factors in T2D remission are under-explored. We have identified a number of methodological issues (comparability, conflicting remission criteria and poorly defined psycho-social interventions) suggesting knowledge gaps which could inform the methodology of future research design. There is significant opportunity for future research to incorporate the social model of disease, conceptualise remission more holistically, and build a more comprehensive evidence base to guide clinical practice.

Experiences and perceptions of self-management in people with prediabetes: A qualitative meta-synthesis

BACKGROUND

Diabetes has become a global public health problem. Strengthening the self-management ability of people with prediabetes plays an important role in preventing the occurrence and development of type 2 diabetes. The aim of this study is to synthesise the self-management experiences and perceptions of people with prediabetes, which can contribute to the development of self-management programs.

METHODS

This review adheres to the ENTREQ Guide. Evidence-based medicine database (JBI and Cochrane) and original literature database (PubMed, Medline, EMbase, Web of Science, Wanfang, CNKI and VIP) were searched up to 31 May 2022. Both Chinese and English literature of qualitative research on self-management experiences and perceptions of prediabetic patients were included. The quality of the included studies was evaluated, and the data were synthesised and analysed by thematic synthesis method.

RESULTS

A total of 23 primary studies containing 504 participants were included. After repeated reading and coding of the literature, three analytical themes were finally identified: coping with role management, success and failure in medical management, seeking and perceiving support.

CONCLUSION

Role management for people with prediabetes needs more attention. Healthcare providers should identify problems from patients' self-management experiences and improve professional skills to assist program modifications. Integrating the self-management program into community activities under the guidance of medical staff and inviting family members and peers to participate can increase involvement and improve the self-management ability.

RELEVANCE TO CLINICAL PRACTICE

These findings describe the different stages and issues in the self-management process of prediabetic patients. The practice of prediabetes self-management should incorporate the psychosocial, physical, and financial issues of the patients. As the main provider of health services, nurses should make patients aware of the susceptibility and severity of prediabetes and help them improve their self-management skills.

NO PATIENT OR PUBLIC CONTRIBUTION

This is a meta-synthesis without direct participation of patients.

Nutrition, Physical Activity, and Prescription of Supplements in Pre- and Post-bariatric Surgery Patients: An Updated Comprehensive Practical Guideline

Only in the USA, 315 billion dollars are spent annually on the medical cost of obesity in adult patients. Till now, bariatric surgery is the most effective method for treating obesity and can play an essential role in reducing the direct and indirect costs of obesity treatment. Nonetheless, there are few comprehensive guidelines which include nutrition, physical activity, and supplements, before and after surgery. The purpose of the present narrative review is to provide an updated and comprehensive practical guideline to help multidisciplinary teams. The core keywords include nutrition, diet, physical activity, exercise, supplements, macronutrients, micronutrients, weight reduction, bariatric surgery, Roux-en-Y Gastric Bypass, Sleeve Gastrostomy, Laparoscopic Adjustable Gastric Banding, and Biliopancreatic diversion with duodenal switch which were searched in databases including PubMed/Medline, Cochrane, and some other sources such as Google Scholar. We answered questions in five important areas: (a) nutritional strategies before bariatric surgery, (b) nutrition after bariatric surgery, (c) physical activity before and after bariatric surgery, (d) weight regain after bariatric surgery, and (e) micronutrient assessments and recommendations before and after bariatric surgery. Some new items were added in this updated guideline including "weight regain" and "pregnancy after bariatric surgery." Other fields were updated based on new evidence and guidelines.

Postmenopausal women's experiences of weight maintenance following a very low energy diet

Introduction

Very low energy diets (VLEDs) effectively induce substantial weight loss in people with obesity, yet they are rarely used as a first line treatment. There is a belief that such diets do not teach the lifestyle behavior changes needed for long-term weight maintenance. However, little is known about the lived experiences of people who have lost weight on a VLED in the long term.

Methods

This study aimed to explore the behaviors and experiences of postmenopausal women who had followed a 4-month VLED (using total meal replacement products [MRPs]), followed by a food-based, moderately energy-restricted diet for an additional 8 months, as part of the TEMPO Diet Trial. Qualitative in-depth semi-structured interviews were conducted with 15 participants at 12 or 24 months (i.e., at 8 or 20 months post diet completion). Transcribed interviews were analyzed thematically using an inductive approach.

Results

Undertaking a VLED was reported by participants to confer advantages in weight maintenance that previous weight loss attempts had not been able to do for them. Firstly, the rapid and significant weight loss, in conjunction with ease of use, was motivational and helped instill confidence in the participants. Secondly, the cessation of a normal diet during the VLED was reported by participants to break weight gain-inducing habits, allowing them to abandon unhelpful habits and to introduce in their place more appropriate attitudes toward weight maintenance. Lastly, the new identity, helpful habits and increased self-efficacy around weight loss supported participants during weight maintenance. Additionally, participants reported that ongoing occasional use of MRPs provided a useful and easy new strategy for countering weight regain and supporting their weight maintenance regimen.

Conclusion

Among the participants in this qualitative study, most of whom had maintained a loss of over 10% of their baseline body weight at the time of interview, using a VLED in the context of a clinical weight loss trial conferred confidence, motivation and skills for weight maintenance. These findings indicate that VLEDs with clinical support could be successfully leveraged to set up behaviors that will support weight maintenance in the long term.

Is Type 2 Diabetes Mellitus a Behavioural Disorder? An Evidence Review for Type 2 Diabetes Mellitus Prevention and Remission through Lifestyle Modification

The prevalence of type 2 diabetes mellitus (T2DM) is steadily rising worldwide due to an increasingly sedentary lifestyle combined with unhealthy food habits. Currently, the burden of diabetes on healthcare systems is unprecedented and rising daily. Several observational studies and randomized controlled trials provide clinical evidence that T2DM remission is possible by adopting dietary interventions and a strict exercise training protocol. Notably, these studies provide ample evidence for remission in patients with T2DM or for prevention in those with risk factors for the disease through various non-pharmacological behavioural interventions. In this article, we present two clinical cases of individuals who showed remission from T2DM/prediabetes via behavioural changes, especially through the adoption of a low-energy diet and exercise. We also discuss the recent advances in T2DM and obesity research, focusing on nutritional interventions and exercise and their benefits for weight loss, improved metabolic profile, enhanced glycaemic control and remission of diabetes.

An Isoenergetic Multifactorial Diet Reduces Pancreatic Fat and Increases Postprandial Insulin Response in Patients With Type 2 Diabetes: A Randomized Controlled Trial

OBJECTIVE

To compare the effect of an isocaloric multifactorial diet with a diet rich in monounsaturated fatty acids (MUFA) and similar macronutrient composition on pancreatic fat (PF) and postprandial insulin response in type 2 diabetes (T2D).

RESEARCH DESIGN AND METHODS

According to a randomized controlled parallel-group design, 39 individuals with T2D, 35-75 years old, in satisfactory blood glucose control, were assigned to an 8 week isocaloric intervention with a multifactorial diet rich in MUFA, polyunsaturated fatty acids, fiber, polyphenols, and vitamins (n = 18) or a MUFA-rich diet (n = 21). Before/after the intervention, PF content was measured by the proton-density fat fraction using a three-dimensional mDIXON MRI sequence, and plasma insulin and glucose concentrations were measured over a 4 h test meal with a similar composition as the assigned diet.

RESULTS

After 8 weeks, PF significantly decreased after the multifactorial diet (from 15.7 ± 6.5% to 14.1 ± 6.3%; P = 0.024), while it did not change after the MUFA diet (from 17.1 ± 10.1% to 18.6 ± 10.6%; P = 0.139) with a significant difference between diets (P = 0.014). Postprandial glucose response was similar in the two groups. Early postprandial insulin response (incremental postprandial areas under the curve [iAUC0-120]) significantly increased with the multifactorial diet (from 36,340 ± 34,954 to 44,138 ± 31,878 pmol/L/min; P = 0.037), while it did not change significantly in the MUFA diet (from 31,754 ± 18,446 to 26,976 ± 12,265 pmol/L/min; P = 0.178), with a significant difference between diets (P = 0.023). Changes in PF inversely correlated with changes in early postprandial insulin response (r = -0.383; P = 0.023).

CONCLUSIONS

In patients with T2D, an isocaloric multifactorial diet, including several beneficial dietary components, markedly reduced PF. This reduction was associated with an improved postprandial insulin response.

Dietary Approaches and Health Outcomes: An Evidence Analysis Center Scoping Review

Appropriate diet can prevent, manage, or reverse noncommunicable health conditions such as obesity, cardiovascular disease, and diabetes. Consequently, the public's interest in diet and nutrition has fueled the multi-billion-dollar weight loss industry and elevated its standing on social media and the internet. Although many dietary approaches are popular, their universal effectiveness and risks across overall populations are not clear. The objective of this scoping review was to identify and characterize systematic reviews (SRs) examining diet or fasting (intermittent energy restriction [IER]) interventions among adults who are healthy or may have chronic disease. An in-depth literature search of six databases was conducted for SRs published between January 2010 and February 2020. A total of 22,385 SRs were retrieved, and 1,017 full-text articles were screened for eligibility. Of these, 92 SRs met inclusion criteria. Covered diets were organized into 12 categories: high/restricted carbohydrate (n = 30), Mediterranean, Nordic, and Tibetan (n = 19), restricted or modified fat (n = 17), various vegetarian diets (n = 16), glycemic index (n = 13), high protein (n = 12), IER (n = 11), meal replacements (n = 11), paleolithic (n = 8), Dietary Approaches to Stop Hypretension (DASH; n = 6), Atkins, South Beach, and Zone (n = 5), and eight other brand diets (n = 4). Intermediate outcomes, such as body weight or composition and cardiometabolic, were commonly reported. Abundant evidence was found exploring dietary approaches in the general population. However, heterogeneity of diet definitions, focus on single macronutrients, and infrequent macronutrient subanalyses were observed. Based on this scoping review, the Evidence Analysis Center prioritized the need to collate evidence related to macronutrient modification, specifically restricted carbohydrate diets.

Delivering the Diabetes Remission Clinical Trial (DiRECT) in primary care: Experiences of healthcare professionals

OBJECTIVE

The Diabetes Remission Clinical Trial (DiRECT) used a formula total diet replacement programme followed by structured weight loss maintenance to induce and sustain weight loss and remission of type 2 diabetes (T2D) in 36% of participants after 2 years. Nurses and dietitians delivering DiRECT in 22 primary care practices in Tyneside and Scotland provided behavioural support to participants. Participant experiences with DiRECT highlighted the key role of support by healthcare professionals (HCPs). We evaluated HCPs' experiences with DiRECT.

RESEARCH DESIGN AND METHODS

Healthcare professionals delivering DiRECT were interviewed at 12 months, while general practices (GPs) were sent an implementation questionnaire. The interviews were analysed thematically. The questionnaires were analysed using frequencies and a narrative synthesis.

RESULTS

Healthcare professionals representing 11 of 22 intervention practices were interviewed and 10 of 22 GPs completed questionnaires. HCPs' initial concerns over perceived potential negative intervention effects, particularly withdrawing anti-diabetes and anti-hypertensive medications, were barriers to engagement. Trust of HCPs towards the research team and perceived credibility of the study facilitated engagement and adoption. Ongoing support by research dietitians was key to the management of participants. Involvement in DiRECT inspired more focus on behaviour modification in the treatment of other people living with T2D in routine practice.

CONCLUSIONS

Diabetes Remission Clinical Trial was considered highly appropriate for the management of T2D in primary care when supported by trained dietitians. Addressing limitations, including varying training needs of HCPs may improve intervention scale-up and tailoring to clinical contexts.

“Dietitians May Only Have One Chance”—The Realities of Treating Obesity in Private Practice in Australia

Introduction: Overweight and obesity are the leading contributors to non-fatal burden of disease in Australia. Very low energy diets (VLEDs) comprising of meal replacement products (MRP) effectively induce substantial weight loss in people with obesity, yet they are rarely used as a first line treatment. Dietitians in private practice are perfectly placed to administer treatments for obesity; however, little is known about the preferred interventions used or their attitudes to incorporating VLEDs and MRPs into their treatments for overweight and obesity. Methods: This study used descriptive qualitative methods to explore accredited practicing dietitians’ (APDs’) perspectives and practices regarding obesity and obesity interventions, including the use of VLEDs and MRPs. Qualitative in-depth semi-structured interviews were conducted with 20 dietitians who had experience in private practice and in treating obesity. Transcribed interviews were analysed thematically using the technique of template analysis. Results: In the context within which dietitians’ practice was found to be a barrier to using evidence-based practice (EBP) for obesity treatment, four overarching themes were found. These were: (1) patient-centred care is the dietitians’ preferred intervention model; (2) VLEDs promote weight loss in specific situations; (3) systemic barriers constrain effective dietetic practice and equitable access to all, and (4) successful outcomes are predicated on working outside of systemic barriers. Conclusion: Dietitians in private practice are well placed and able to provide life-enhancing and evidence-based treatments for overweight and obesity and associated chronic disease in the community. However, systemic barriers need to be addressed to provide equitable access to effective care irrespective of socio-economic status.

Participant experiences in the Diabetes REmission Clinical Trial (DiRECT)

INTRODUCTION

The Diabetes REmission Clinical Trial (DiRECT) has shown that sustained remission of type 2 diabetes in primary care is achievable through weight loss using total diet replacement (TDR) with continued behavioural support. Understanding participants' experiences can help optimise the intervention, support implementation into healthcare, and understand the process of behaviour change.

METHODS

Thirty-four DiRECT participants were recruited into this embedded qualitative evaluation study. In-person and telephone interviews were conducted before the TDR; at week 6-8 of the TDR; 2 weeks into food reintroduction (FR); and at 1 year, to learn about participant experiences with the programme. Transcribed narratives were analysed thematically, and we used interpretation to develop overarching themes.

RESULTS

Initiation of the TDR and transition to FR were challenging and required increased behavioural support. In general, adhering to TDR proved easier than the participants had anticipated. Some participants chose the optional extension of TDR. Rapid weight loss and changes in diabetes markers provided ongoing motivation. Further weight loss, behavioural support and occasional use of TDR facilitated weight loss maintenance (WLM). A process of behaviour adaptation to change following regime disruption was identified in three stages: (1) expectations of the new, (2) overcoming difficulties with adherence, and (3) acceptance of continuous effort and establishment of routines.

CONCLUSIONS

The DiRECT intervention was acceptable and regularity, continuity, and tailoring of behavioural support was instrumental in its implementation in primary care. The adaptation process accounts for some of the individual variability of experiences with the intervention and highlights the need for programme flexibility.

Diets for weight management in adults with type 2 diabetes: an umbrella review of published meta-analyses and systematic review of trials of diets for diabetes remission

AIMS/HYPOTHESIS

Weight reduction is fundamental for type 2 diabetes management and remission, but uncertainty exists over which diet type is best to achieve and maintain weight loss. We evaluated dietary approaches for weight loss, and remission, in people with type 2 diabetes to inform practice and clinical guidelines.

METHODS

First, we conducted a systematic review of published meta-analyses of RCTs of weight-loss diets. We searched MEDLINE (Ovid), PubMed, Web of Science and Cochrane Database of Systematic Reviews, up to 7 May 2021. We synthesised weight loss findings stratified by diet types and assessed meta-analyses quality with A Measurement Tool to Assess Systematic Reviews (AMSTAR) 2. We assessed certainty of pooled results of each meta-analysis using Grading of Recommendations, Assessment, Development and Evaluations (GRADE) (PROSPERO CRD42020169258). Second, we conducted a systematic review of any intervention studies reporting type 2 diabetes remission with weight-loss diets, in MEDLINE (via PubMed), Embase and Cochrane Central Register of Controlled Trials, up to 10 May 2021. Findings were synthesised by diet type and study quality (Cochrane Risk of Bias tool 2.0 and Risk Of Bias In Non-randomised Studies - of Interventions [ROBINS-I]), with GRADE applied (PROSPERO CRD42020208878).

RESULTS

We identified 19 meta-analyses of weight-loss diets, involving 2-23 primary trials (n = 100-1587), published 2013-2021. Twelve were 'critically low' or 'low' AMSTAR 2 quality, with seven 'high' quality. Greatest weight loss was reported with very low energy diets, 1.7-2.1 MJ/day (400-500 kcal) for 8-12 weeks (high-quality meta-analysis, GRADE low), achieving 6.6 kg (95% CI -9.5, -3.7) greater weight loss than low-energy diets (4.2-6.3 MJ/day [1000-1500 kcal]). Formula meal replacements (high quality, GRADE moderate) achieved 2.4 kg (95% CI -3.3, -1.4) greater weight loss over 12-52 weeks. Low-carbohydrate diets were no better for weight loss than higher-carbohydrate/low-fat diets (high quality, GRADE high). High-protein, Mediterranean, high-monounsaturated-fatty-acid, vegetarian and low-glycaemic-index diets all achieved minimal (0.3-2 kg) or no difference from control diets (low to critically low quality, GRADE very low/moderate). For type 2 diabetes remission, of 373 records, 16 met inclusion criteria. Remissions at 1 year were reported for a median 54% of participants in RCTs including initial low-energy total diet replacement (low-risk-of-bias study, GRADE high), and 11% and 15% for meal replacements and Mediterranean diets, respectively (some concerns for risk of bias in studies, GRADE moderate/low). For ketogenic/very low-carbohydrate and very low-energy food-based diets, the evidence for remission (20% and 22%, respectively) has serious and critical risk of bias, and GRADE certainty is very low.

CONCLUSIONS/INTERPRETATION

Published meta-analyses of hypocaloric diets for weight management in people with type 2 diabetes do not support any particular macronutrient profile or style over others. Very low energy diets and formula meal replacement appear the most effective approaches, generally providing less energy than self-administered food-based diets. Programmes including a hypocaloric formula 'total diet replacement' induction phase were most effective for type 2 diabetes remission. Most of the evidence is restricted to 1 year or less. Well-conducted research is needed to assess longer-term impacts on weight, glycaemic control, clinical outcomes and diabetes complications.

Restricting carbohydrates and calories in the treatment of type 2 diabetes: a systematic review of the effectiveness of 'low-carbohydrate' interventions with differing energy levels

There are two proven dietary approaches to shift type 2 diabetes (T2D) into remission: low-energy diets (LEDs) and low-carbohydrate diets (LCDs). These approaches differ in their rationale and application yet both involve carbohydrate restriction, either as an explicit goal or as a consequence of reducing overall energy intake. The aims of this systematic review were to identify, characterise and compare existing clinical trials that utilised ‘low-carbohydrate’ interventions with differing energy intakes. Electronic databases CENTRAL, CINAHL, Embase, MEDLINE and Scopus were searched to identify controlled clinical trials in adults with T2D involving low-carbohydrate intake (defined as <130 g carbohydrate/d) and reporting weight and glycaemic outcomes. The initial database search yielded 809 results, of which fifteen studies met the inclusion criteria. Nine out of fifteen studies utilised LCDs with moderate or unrestricted energy intake. Six trials utilised LEDs (<1200 kcal/d), with all except one incorporating meal replacements as part of a commercial weight loss programme. Interventions using both restricted and unrestricted (ad libitum) energy intakes produced clinically significant weight loss and reduction in glycated haemoglobin (HbA1c) at study endpoints. Trials that restricted energy intake were not superior to those that allowed ad libitum low-carbohydrate feeding at 12 and 24 months. An association was observed across studies between average weight loss and reduction in HbA1c at 6, 12 and 24 months, indicating that sustained weight loss is key to T2D remission. Further research is needed to specifically ascertain the weight-independent effects of carbohydrate restriction on glycaemic control in T2D.

Evaluation of the Low Carb Program Digital Intervention for the Self-Management of Type 2 Diabetes and Prediabetes in an NHS England General Practice: Single-Arm Prospective Study

Background

Type 2 diabetes mellitus has serious health consequences, including blindness, amputation, and stroke. Researchers and clinicians are increasingly in agreement that type 2 diabetes may be effectively treated with a carbohydrate-reduced diet. Digital apps are increasingly used as an adjunct to traditional health care provisions to support remote self-management of long-term health conditions.

Objective

Our objective was to evaluate the real-world 12-month outcomes of patients prescribed the Low Carb Program digital health intervention at a primary care National Health Service (NHS) site. The Low Carb Program is a nutritionally focused, 12-session, digitally delivered, educational behavior change intervention for glycemic control and weight loss for adults with prediabetes and type 2 diabetes. The program educates and supports sustainable dietary changes focused on carbohydrate restriction by utilizing behavior change techniques, including goal setting, peer support, and behavioral self-monitoring, as well as personalized downloadable resources, including recipes and meal plans tailored to ethnicity, weekly shopping budget, and dietary preferences.

Methods

This study evaluated the real-world outcomes of patients recruited to the Low Carb Program at an NHS general practice in Southport, United Kingdom. All of the NHS patients recruited to the program were diagnosed with type 2 diabetes or prediabetes and were given access to the program at no cost. A total of 45 participants, with a mean age of 54.8 years (SD 13.2), were included in the study. Women made up 42% (19/45) of the sample. The mean hemoglobin A_1c (HbA_1c) of the sample was 56.7 mmol/mol (SD 16.95) and the mean body weight was 89.4 kg (SD 13.8).

Results

Of the 45 study participants recruited to the program, all of them (100%) activated their accounts and 37 (82%) individuals reported outcomes at 12 months. All 45 (100%) patients completed at least 40% of the lessons and 32 (71%) individuals completed more than nine out of 12 core lessons of the program. Glycemic control and weight loss improved, particularly for participants who completed more than nine core lessons in the program over 12 months. The mean HbA_1c went from 58.8 mmol/mol at baseline to 54.0 mmol/mol, representing a mean reduction of 4.78 mmol/mol (SD 4.60; t₃₁=5.87; P<.001). Results showed an average total body weight reduction of 4.17%, with an average weight reduction of 3.85 kg (SD 2.49; t₃₁=9.27; P<.001) at the 12-month follow-up point.

Conclusions

A digital app prescribed to adults with type 2 diabetes and prediabetes in a primary care setting supporting a transition to a low-carbohydrate diet has been shown to be effective in improving glycemic control and enabling weight loss. Further research to understand more about factors affecting engagement with the app and further positive health implications would be valuable.

Factors associated with engagement and adherence to a low-energy diet to promote 10% weight loss in patients with clinically significant non-alcoholic fatty liver disease

Objective

Clinical guidelines recommend weight loss to manage non-alcoholic fatty liver disease (NAFLD). However, the majority of patients find weight loss a significant challenge. We identified factors associated with engagement and adherence to a low-energy diet (LED) as a treatment option for NAFLD.

Design

23 patients with NAFLD enrolled in a LED (~800 kcal/day) were individually interviewed. Transcripts were thematically analysed.

Results

14/23 patients achieved ≥10% weight loss, 18/23 achieved ≥7% weight loss and 19/23 achieved ≥5% weight loss. Six themes were generated from the data. A desire to achieve rapid weight loss to improve liver health and prevent disease progression was the most salient facilitator to engagement. Early and significant weight loss, accountability to clinicians and regular appointments with personalised feedback were facilitators to engagement and adherence. The desire to receive positive reinforcement from a consultant was a frequently reported facilitator to adherence. Practical and emotional support from friends and family members was critically important outside of the clinical setting. Irregular working patterns preventing attendance at appointments was a barrier to adherence and completion of the intervention.

Conclusions

Engagement and adherence to a LED in patients with NAFLD were encouraged by early and rapid weight loss, personalised feedback and positive reinforcement in the clinical setting combined with ongoing support from friends and family members. Findings support those identified in patients who completed a LED to achieve type 2 diabetes remission and highlight the importance of behaviour change support during the early stages of a LED to promote adherence.

Feasibility of a Very Low Calorie Diet to Achieve a Sustainable 10% Weight Loss in Patients With Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is the most common liver condition worldwide. A weight loss goal of ≥10% is the recommended treatment for NAFLD; however, only a minority of patients achieve this level of weight reduction with standard dietary approaches. This study aimed to determine whether a very low calorie diet (VLCD) is an acceptable and feasible therapy to achieve and maintain a ≥10% weight loss in patients with clinically significant NAFLD.

Brief formula low-energy-diet for relapse management during weight loss maintenance in the Diabetes Remission Clinical Trial (DiRECT)

BACKGROUND

Weight loss maintenance (WLM) is critical for sustaining type 2 diabetes (T2D) remission, but poorly evidenced. We evaluated brief return to formula low-energy-diet (LED) as relapse treatments (RTs) during the WLM phase of the Diabetes Remission Clinical Trial (DiRECT).

METHODS

This post-hoc evaluation included all participants commencing the WLM phase of DiRECT. The protocol offered RT when regain of >2 kg occurred.

RESULTS

In total, 123/149 (83%) DiRECT intervention participants commenced the WLM phase after 26 (17%) had withdrawn prior to the WLM phase. Most participants [99/123 (80%)] regained >2 kg during the WLM phase, among whom 60/99 (61%) were recorded as using RT and 39/99 (39%) not using any RT. At baseline, RT users had a higher mean (SD) body mass index [35.8 (4.9) kg m^-2 vs. 33.8 (3.9) kg m^-2 , p = 0.0231] and had greater social deprivation (P = 0.0003) than non-users, although otherwise the groups were similar. Weight loss ≥ 2k g was achieved in 30/93 (32%) of RT attempts. At 2 years, those regaining >2 kg and using RT (n = 60) had mean (SD) weight losses of 7.4 (6.1) kg, with 25 (42%) remissions and 7 (12%) programme withdrawals. Those regaining >2 kg but not using RT (n = 39) had weight losses of 8.8 (6.0) kg, with 21 (54%) remissions and 4 (10%) programme withdrawals (all not significant). Twelve participants were never recorded as having regained >2 kg or using RTs and, at 2 years, their weight losses were 12.9 (9.2) kg, with 4 (33%) remissions and 8 (67%) programme withdrawals.

CONCLUSIONS

Most people with T2D experience weight regain >2 kg during the 2 years after substantial weight loss with a LED. Only one-third of RTs corrected their 2-kg regain, resulting in similar weight losses, remissions and programme withdrawals at 2 years compared to those not using RTs; however, both groups had weight losses below those not recorded as regaining >2 kg during WLM.

Current Perspectives on the Role of Very-Low-Energy Diets in the Treatment of Obesity and Type 2 Diabetes in Youth

In both developed and developing countries, pediatric obesity and type 2 diabetes are an increasing public health concern: globally 5.6% of girls and 7.8% of boys aged ≥5 years have obesity. The incidence of type 2 diabetes has increased in youth in recent decades and disproportionately affects those from ethnic/racial minority groups and disadvantaged backgrounds. For the treatment of both conditions, conventional lifestyle intervention is frequently ineffective, access to bariatric surgery is very limited and many young people are unsuitable or unwilling to undergo surgery. A very-low-energy diet (VLED) provides a viable alternative and may be effective for weight reduction and improved glycemic control in youth, based on one systematic review. In particular, in the treatment of type 2 diabetes, a chart review and a pilot study both demonstrated that a VLED can reduce the requirement for medications, including insulin, and lead to the remission of diabetes. However, long-term follow-up and safety data remain limited and therefore a VLED is inconsistently recommended by clinical practice guidelines for the treatment of pediatric obesity and type 2 diabetes. In clinical practice, VLED use in children and adolescents is uniquely challenging due to intolerance of expected side effects, difficulty adhering to the highly restrictive diet and difficulty with behaviour change within the current social context and environment. Ultimately, more research, including larger, longer-term trials with comprehensive safety monitoring are required to strengthen the evidence base. This would inform clinical practice guidelines, which may facilitate more widespread utilization of VLED programs in the management of obesity and type 2 diabetes in youth.

Effects on body weight, eating behavior, and quality of life of a low-energy diet combined with behavioral group treatment of persons with class II or III obesity: A 2-year pilot study

Objective

Obesity is associated with reduced health‐related quality of life (HRQoL). Outcomes of nonsurgical weight loss treatment on HRQoL are inconsistent and it is unclear how much weight reduction, or what type of treatment, is required for significant improvements. This study aimed to evaluate the effects of a lifestyle intervention program on weight, eating behaviors, and HRQoL, and to describe participants' experiences of treatment.

Methods

This 2‐year intervention trial in persons with class II or III obesity comprised a 3‐month liquid low‐energy diet (880 kcal/d) followed by a 3‐month reintroduction to regular foods, combined with behavioral group treatment.

Results

Fifty‐five participants (73% women) were included, mean (SD) age 43.2 (12.4) years, and mean body mass index 42.0 (6.0) kg/m². Mean weight loss at 6, 12, and 24 months was 18.9%, 13.7%, and 7.2%, respectively. Short‐ and long‐term effects on eating behavior were favorable. Twelve of 14 HRQoL domains were improved at 6 months, compared to eight domains at 12 months. After 24 months, 2 of 14 domains, physical and psychosocial functioning, were improved. The treatment program was well accepted by the participants.

Conclusions

Substantial weight loss after 6 months was associated with extensive improvements in HRQoL, comprising the physical, psychosocial, and mental domains. Significant weight regain was observed between 6 and 24 months follow‐up. Modest weight loss after 24 months was associated with moderate improvement in physical functioning and large improvement in psychosocial functioning. The effect on psychosocial functioning is most likely related to both weight loss and behavioral treatment.

Beyond Body Weight-Loss: Dietary Strategies Targeting Intrahepatic Fat in NAFLD

Non-alcoholic fatty liver disease (NAFLD) has emerged as the most prevalent liver disease in industrialized countries. It is regarded as the hepatic manifestation of the metabolic syndrome (MetS) resulting from insulin resistance. Moreover, insulin resistance impairs glycogen synthesis, postprandially diverting a substantial amount of carbohydrates to the liver and storing them there as fat. NAFLD has far-reaching metabolic consequences involving glucose and lipoprotein metabolism disorders and risk of cardiovascular disease, the leading cause of death worldwide. No pharmaceutical options are currently approved for the treatment of NAFLD. Exercise training and dietary interventions remain the cornerstone of NAFLD treatment. Current international guidelines state that the primary goal of nutritional therapy is to reduce energy intake to achieve a 7%-10% reduction in body weight. Meal replacement therapy (formula diets) results in more pronounced weight loss compared to conventional calorie-restricted diets. However, studies have shown that body mass index (BMI) or weight reduction is not obligatory for decreasing hepatic fat content or to restore normal liver function. Recent studies have achieved significant reductions in liver fat with eucaloric diets and without weight loss through macronutrient modifications. Based on this evidence, an integrative nutritional therapeutic concept was formulated that combines the most effective nutrition approaches termed "liver-fasting." It involves the temporary use of a low calorie diet (total meal replacement with a specific high-protein, high-soluble fiber, lower-carbohydrate formula), followed by stepwise food reintroduction that implements a Mediterranean style low-carb diet as basic nutrition.

Efficacy of Intermittent or Continuous Very Low-Energy Diets in Overweight and Obese Individuals with Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analyses

OBJECTIVE

This study is aimed at investigating the efficacy of a very low-energy diet (VLED) in overweight and obese individuals with type 2 diabetes mellitus (T2DM).

METHODS

We thoroughly searched eight electronic resource databases of controlled studies concerning the efficacy and acceptability of intermittent or continuous VLEDs in patients with T2DM compared with other energy restriction interventions.

RESULTS

Eighteen studies (11 randomized and seven nonrandomized controlled trials) with 911 participants were included. The meta-analyses showed that compared with a low-energy diet (LED) and mild energy restriction (MER), VLED is superior in the reduction of body weight (mean difference (MD) MD_LED = -2.77, 95% confidence interval (CI) CI_LED = -4.81 to - 0.72, P _LED = 0.008; MD_MER = -6.72, 95%CI_MER = -10.05 to - 3.39, P _LED = 0.008; MD_MER = -6.72, 95%CI_MER = -10.05 to - 3.39, P _LED = 0.008; MD_MER = -6.72, 95%CI_MER = -10.05 to - 3.39, P _LED = 0.008; MD_MER = -6.72, 95%CI_MER = -10.05 to - 3.39, P _LED = 0.008; MD_MER = -6.72, 95%CI_MER = -10.05 to - 3.39, P _LED = 0.008; MD_MER = -6.72, 95%CI_MER = -10.05 to - 3.39, P _LED = 0.008; MD_MER = -6.72, 95%CI_MER = -10.05 to - 3.39, I ² = 0%) and TG level (MD = -0.25, 95%CI = -0.55 to 0.06, P _LED = 0.008; MD_MER = -6.72, 95%CI_MER = -10.05 to - 3.39, I ² = 0%) and TG level (MD = -0.25, 95%CI = -0.55 to 0.06, P _LED = 0.008; MD_MER = -6.72, 95%CI_MER = -10.05 to - 3.39, P _LED = 0.008; MD_MER = -6.72, 95%CI_MER = -10.05 to - 3.39, P _LED = 0.008; MD_MER = -6.72, 95%CI_MER = -10.05 to - 3.39, P _LED = 0.008; MD_MER = -6.72, 95%CI_MER = -10.05 to - 3.39, P _LED = 0.008; MD_MER = -6.72, 95%CI_MER = -10.05 to - 3.39.

CONCLUSION

Dietary intervention through VLEDs is an effective therapy for rapid weight loss, glycemic control, and improved lipid metabolism in overweight and obese individuals with T2DM. Thus, VLEDs should be encouraged in overweight and obese individuals with T2DM who urgently need weight loss and are unsuitable or unwilling to undergo surgery. As all outcome indicators have low or extremely low quality after GRADE evaluation, further clinical trials that focus on the remission effect of VLEDs on T2DM are needed.

Efficacy of low- and very-low-energy diets in people with type 2 diabetes mellitus: A systematic review and meta-analysis of interventional studies

AIMS

To review systematically and quantify the weight loss achieved through low- (LEDs) and very-low-energy diets (VLEDs) in people with type 2 diabetes mellitus (T2DM).

MATERIALS AND METHODS

Studies reporting the effects of diet-only interventions of up to 1600 kcal/d in people with T2DM were searched in MEDLINE, EMBASE and CINAHL up to July 2018. Changes in the primary (body weight and body mass index [BMI]) and secondary outcomes (glycated haemoglobin, blood lipids) according to energy restriction and duration of diet were modelled using restricted cubic splines.

RESULTS

Forty-four studies (3817 participants) were included. The overall quality of the evidence was moderate and limited to short-term interventions up to 4 months. Baseline mean weight and BMI were 92.1 kg and 36.6 kg/m² . VLEDs of 400 kcal/d led to 5.4% weight loss at 2 weeks, increasing to 17.9% at 3 months. More modest reductions of 7.3% were observed on LEDs of 1200 kcal/d and 2.0% on 1600 kcal/d after 3 months. No clear patterns emerged for secondary outcomes. Publication bias was significant for primary outcomes.

CONCLUSIONS

Through modelling, we were able to describe effective dietary deficit strategies to achieve weight reduction up to 4 months in people with T2DM. High-quality studies are required to further support clinical practice with evidence-based dietary interventions.

A systematic review and meta-analysis of the effectiveness of meal replacements for weight loss

Meal replacements (MR) are generally not recommended in clinical guidelines for the management of obesity. The aim of this review is to provide an up-to-date systematic evaluation of the effect of weight loss interventions incorporating MR compared with alternative interventions on weight change at 1 year in adults with overweight or obesity. Six electronic databases were searched from inception to the end of August 2018 for randomized controlled trials comparing the effect of MR with interventions that did not include MR on weight at 1 year. We excluded studies using diets providing <3347 kJ/(800 kcal)/day and those which used total diet replacement (TDR) from this review. Risk of bias was assessed using the Cochrane risk of bias tool. Twenty-three studies with 7884 adult participants were included. Six out of 23 studies were judged at low risk of bias across all domains, and 5/23 studies were judged at high risk of bias in at least one domain. Studies with similar intervention and comparators were grouped into five comparisons for analysis. Mean weight change at 1 year favoured the MR group relative to the control group in each comparison. In those comparisons where we conducted meta-analysis, in people assigned to a diet incorporating MR, mean difference was -1.44 kg (-2.48 to -0.39 kg; I²  = 38%) compared with alternative kinds of diets. In those assigned to a MR diet along with support, mean difference was -2.22 kg (-3.99 to -0.45, I²  = 81%) compared with other diets with support and -3.87 kg (-7.34 to -0.40; I²  = 60%) compared with other kinds of diet without support. In those assigned a MR diet with an enhanced level of support, mean difference was -6.13 kg (-7.35 to -4.91, I²  = 19%) compared with alternative diets and regular support. Programmes incorporating meal replacements led to greater weight loss at 1 year than comparator weight loss programmes and should be considered as a valid option for management of overweight and obesity in community and health care settings.

Bariatric surgery, lifestyle interventions and orlistat for severe obesity: the REBALANCE mixed-methods systematic review and economic evaluation

BACKGROUND

Adults with severe obesity [body mass index (BMI) of ≥ 35 kg/m2] have an increased risk of comorbidities and psychological, social and economic consequences.

OBJECTIVES

Systematically review bariatric surgery, weight-management programmes (WMPs) and orlistat pharmacotherapy for adults with severe obesity, and evaluate the feasibility, acceptability, clinical effectiveness and cost-effectiveness of treatment.

DATA SOURCES

Electronic databases including MEDLINE, EMBASE, PsycINFO, the Cochrane Central Register of Controlled Trials and the NHS Economic Evaluation Database were searched (last searched in May 2017).

REVIEW METHODS

Four systematic reviews evaluated clinical effectiveness, cost-effectiveness and qualitative evidence for adults with a BMI of ≥ 35 kg/m2. Data from meta-analyses populated a microsimulation model predicting costs, outcomes and cost-effectiveness of Roux-en-Y gastric bypass (RYGB) surgery and the most effective lifestyle WMPs over a 30-year time horizon from a NHS perspective, compared with current UK population obesity trends. Interventions were cost-effective if the additional cost of achieving a quality-adjusted life-year is < £20,000-30,000.

RESULTS

A total of 131 randomised controlled trials (RCTs), 26 UK studies, 33 qualitative studies and 46 cost-effectiveness studies were included. From RCTs, RYGB produced the greatest long-term weight change [-20.23 kg, 95% confidence interval (CI) -23.75 to -16.71 kg, at 60 months]. WMPs with very low-calorie diets (VLCDs) produced the greatest weight loss at 12 months compared with no WMPs. Adding a VLCD to a WMP gave an additional mean weight change of -4.41 kg (95% CI -5.93 to -2.88 kg) at 12 months. The intensive Look AHEAD WMP produced mean long-term weight loss of 6% in people with type 2 diabetes mellitus (at a median of 9.6 years). The microsimulation model found that WMPs were generally cost-effective compared with population obesity trends. Long-term WMP weight regain was very uncertain, apart from Look AHEAD. The addition of a VLCD to a WMP was not cost-effective compared with a WMP alone. RYGB was cost-effective compared with no surgery and WMPs, but the model did not replicate long-term cost savings found in previous studies. Qualitative data suggested that participants could be attracted to take part in WMPs through endorsement by their health-care provider or through perceiving innovative activities, with WMPs being delivered to groups. Features improving long-term weight loss included having group support, additional behavioural support, a physical activity programme to attend, a prescribed calorie diet or a calorie deficit.

LIMITATIONS

Reviewed studies often lacked generalisability to UK settings in terms of participants and resources for implementation, and usually lacked long-term follow-up (particularly for complications for surgery), leading to unrealistic weight regain assumptions. The views of potential and actual users of services were rarely reported to contribute to service design. This study may have failed to identify unpublished UK evaluations. Dual, blinded numerical data extraction was not undertaken.

CONCLUSIONS

Roux-en-Y gastric bypass was costly to deliver, but it was the most cost-effective intervention. Adding a VLCD to a WMP was not cost-effective compared with a WMP alone. Most WMPs were cost-effective compared with current population obesity trends.

FUTURE WORK

Improved reporting of WMPs is needed to allow replication, translation and further research. Qualitative research is needed with adults who are potential users of, or who fail to engage with or drop out from, WMPs. RCTs and economic evaluations in UK settings (e.g. Tier 3, commercial programmes or primary care) should evaluate VLCDs with long-term follow-up (≥ 5 years). Decision models should incorporate relevant costs, disease states and evidence-based weight regain assumptions.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42016040190.

FUNDING

The National Institute for Health Research Health Technology Assessment programme. The Health Services Research Unit and Health Economics Research Unit are core funded by the Chief Scientist Office of the Scottish Government Health and Social Care Directorate.

Experiences of using very low energy diets for weight loss by people with overweight or obesity: a review of qualitative research

Although very low energy diets (VLEDs) are the most successful non-surgical, non-pharmacological treatment for obesity, they are underutilized, and little is known about experiences of people using VLEDs for weight loss. This systematic review synthesizes qualitative studies investigating participants' experiences of undertaking a VLED composed of total meal replacement products to lose weight. Of the 4,911 articles screened, three studies met criteria for inclusion. Thematic synthesis was used to analyse the study findings. Health and appearance were the main motivators to use a VLED for weight loss. Adherence was facilitated by group support meetings, rapid weight loss and ease of use of the diet. Being part of a clinical trial gave a sense of accountability and further reason to adhere to a VLED, and the VLED itself was well accepted by users. Barriers to adherence, such as temptations and social occasions, were overcome by avoidance and distraction strategies. In conclusion, this qualitative synthesis of users' experiences of VLEDs shows that VLEDs are well accepted and positively viewed by users. More in-depth research could facilitate understanding of how this weight loss strategy influences the weight maintenance period, in order to facilitate better long-term results.

Acceptability of a very-low-energy diet in Type 2 diabetes: patient experiences and behaviour regulation

AIMS

To evaluate the acceptability of an 8-week very-low-energy diet for remission of Type 2 diabetes, and to identify barriers and facilitators of adherence and behaviour-regulation strategies used by participants in the Counterbalance study.

METHODS

Eighteen of 30 participants in the Counterbalance study (ISRCTN88634530) took part in semi-structured interviews. Of these, 15 participants were interviewed before and after the 8-week very-low-energy diet intervention. Thematic analysis was used to analyse the narratives.

RESULTS

The prospect of diabetes remission, considerable weight loss, and long-term health improvement provided participants with substantial initial motivation. This motivation was sustained through the experience of rapid weight loss, improvements in blood glucose levels, social support and increased physical and psychological well-being. Overall, adherence to the very-low-energy diet for 8 weeks was perceived as much easier than anticipated, but required personal effort. Participants addressed challenges by removing food from the environment, planning, avoidance of tempting situations or places, and self-distraction. Weight loss and improvements in blood glucose levels lead to a sense of achievement and improvements in physical and psychological wellbeing.

CONCLUSIONS

Dietary treatment for reversal of Type 2 diabetes is acceptable and feasible in motivated participants, and the process is perceived as highly gratifying. Research outside of controlled trial settings is needed to gauge the generalisability of these findings.

Assessing the evidence for weight loss strategies in people with and without type 2 diabetes

This review will examine topical issues in weight loss and weight maintenance in people with and without diabetes. A high protein, low glycemic index diet would appear to be best for 12-mo weight maintenance in people without type 2 diabetes. This dietary pattern is currently being explored in a large prevention of diabetes intervention. Intermittent energy restriction is useful but no better than daily energy restriction but there needs to be larger and longer term trials performed. There appears to be no evidence that intermittent fasting or intermittent severe energy restriction has a metabolic benefit beyond the weight loss produced and does not spare lean mass compared with daily energy restriction. Meal replacements are useful and can produce weight loss similar to or better than food restriction alone. Very low calorie diets can produce weight loss of 11-16 kg at 12 mo with persistent weight loss of 1-2 kg at 4-6 years with a very wide variation in long term results. Long term medication or meal replacement support can produce more sustained weight loss. In type 2 diabetes very low carbohydrate diets are strongly recommended by some groups but the long term evidence is very limited and no published trial is longer than 12 mo. Although obesity is strongly genetically based the microbiome may play a small role but human evidence is currently very limited.

Effects of very low calorie diets on liver size and weight loss in the preoperative period of bariatric surgery: a systematic review

Restrictive diet implementation in bariatric surgery (BS) preoperative period is common, although its benefits are not well established. This study aimed to assess the effects of very low calorie diets (VLCD) on liver size and weight loss during BS preoperative period. Surgery-related complications were also assessed. A systematic review of the literature was performed. Terms such as "bariatric surgery" and "very low energy diet" were included in the search strategy. Inclusion criteria were adult patients (aged>18 yr); VLCD treatment in BS preoperative period (10 d to 12 wk); and assessment of 1 the following outcomes: weight loss, liver volume reduction, and surgical complications. There were 9 studies included (849 patients including 250 controls, 196 controls without VLCD). Of the studies, 3 were randomized clinical trials and 6 were observational studies. VLCD treatment led to weight loss (-2.8 to -14.8 kg) and to liver size reduction by 5% to 20% of the initial volume. VLCD treatment did not significantly reduce perioperative complications. However, 1 study (n = 273) reported a protective effect 30 days after surgery. This systematic review found VLCD treatment led to significant weight loss and liver volume reduction when applied to patients with obesity in BS preoperative period. The effect of VLCD on surgical risks is not clear. Standardization of dietary characteristics is needed, because weight loss and decrease in liver size were not connected to higher caloric restriction. This is an important matter in clinical practice as to avoid unnecessary prolonged and/or excessive dietary restriction.

The Diabetes Remission Clinical Trial (DiRECT): protocol for a cluster randomised trial

Background

Despite improving evidence-based practice following clinical guidelines to optimise drug therapy, Type 2 diabetes (T2DM) still exerts a devastating toll from vascular complications and premature death. Biochemical remission of T2DM has been demonstrated with weight loss around 15kg following bariatric surgery and in several small studies of non-surgical energy-restriction treatments. The non-surgical Counterweight-Plus programme, running in Primary Care where obesity and T2DM are routinely managed, produces >15 kg weight loss in 33 % of all enrolled patients. The Diabetes UK-funded Counterpoint study suggested that this should be sufficient to reverse T2DM by removing ectopic fat in liver and pancreas, restoring first-phase insulin secretion.

The Diabetes Remission Clinical Trial (DiRECT) was designed to determine whether a structured, intensive, weight management programme, delivered in a routine Primary Care setting, is a viable treatment for achieving durable normoglycaemia. Other aims are to understand the mechanistic basis of remission and to identify psychological predictors of response.

Methods/Design

Cluster-randomised design with GP practice as the unit of randomisation: 280 participants from around 30 practices in Scotland and England will be allocated either to continue usual guideline-based care or to add the Counterweight-Plus weight management programme, which includes primary care nurse or dietitian delivery of 12-20weeks low calorie diet replacement, food reintroduction, and long-term weight loss maintenance. Main inclusion criteria: men and women aged 20-65years, all ethnicities, T2DM 0-6years duration, BMI 27-45 kg/m². Tyneside participants will undergo Magnetic Resonance (MR) studies of pancreatic and hepatic fat, and metabolic studies to determine mechanisms underlying T2DM remission. Co-primary endpoints: weight reduction ≥ 15 kg and HbA1c <48 mmol/mol at one year. Further follow-up at 2 years.

Discussion

This study will establish whether a structured weight management programme, delivered in Primary Care by practice nurses or dietitians, is a viable treatment to achieve T2DM remission. Results, available from 2018 onwards, will inform future service strategy.

Trial registration

Current Controlled Trials ISRCTN03267836. Date of Registration 20/12/2013

Electronic supplementary material

The online version of this article (doi:10.1186/s12875-016-0406-2) contains supplementary material, which is available to authorized users.