Completely Plant-Based Diets That Meet Energy Requirements for Resistance Training Can Supply Enough Protein and Leucine to Maximize Hypertrophy and Strength in Male Bodybuilders: A Modeling Study

Despite increasing awareness of plant-based diets for health and athletic performance, athletes are cautioned that careful dietary monitoring is necessary. Whether commonly consumed plant-based diets are nutritionally adequate for maximal muscular hypertrophy remains unknown. This modeling study assessed the nutrient composition of completely plant-based diets scaled to the caloric demands of maximal muscle mass and strength development in adult male bodybuilders. To model calorie requirements, anthropometric data from bodybuilders were input into the Tinsley resting metabolic rate prediction equation, and an appropriate physical activity factor and calorie surplus were applied. Dietary data from a large cohort following completely plant-based diets were then scaled to meet these needs. Modeled intakes for nutrients of interest were calculated as 1.8 g/kg/day of protein and 2.75 g/meal of leucine, which surpass mean requirements for maximal increases in muscle mass and strength and muscle protein synthesis, respectively. Daily levels for all micronutrients, except vitamin D, also exceeded requirements. Saturated fat levels were aligned with dietary guidelines, although sodium levels exceeded recommended limits. Consumption of larger portions of commonplace plant-based diets, scaled to meet the energy demands of maximal accrual of muscle mass and strength, satisfied protein and leucine requirements without the need for additional planning.

Lifestyle Medicine Implementation in 8 Health Systems: Protocol for a Multiple Case Study Investigation

BACKGROUND

Lifestyle medicine (LM) is the use of therapeutic lifestyle changes (including a whole-food, plant-predominant eating pattern; regular physical activity; restorative sleep; stress management; avoidance of risky substances; and positive social connection) to prevent and treat chronic illness. Despite growing evidence, LM is still not widely implemented in health care settings. Potential challenges to LM implementation include lack of clinician training, staffing concerns, and misalignment of LM services with fee-for-service reimbursement, but the full range of factors facilitating or obstructing its implementation and long-term success are not yet understood. To learn important lessons for success and failure, it is crucial to understand the experiences of different LM programs.

OBJECTIVE

This study aims to describe in depth the protocol used to identify barriers and facilitators impacting the implementation of LM in health systems.

METHODS

The study team comprises team members at the American College of Lifestyle Medicine (ACLM), including staff and researchers with expertise in public health, LM, and qualitative research. We recruited health systems that were members of the ACLM Health Systems Council. From among 15 self-nominating health systems, we selected 7 to represent a diversity of geographic location, type, size, expertise, funding, patients, and LM services. Partway through the study, we recruited 1 additional contrasting health system to serve as a negative case. For each case, we conducted in-depth interviews, document reviews, site visits (limited due to the COVID-19 pandemic), and study team debriefs. Interviews lasted 45-90 minutes and followed a semistructured interview guide, loosely based on the Consolidated Framework for Implementation Research (CFIR) model. We are constructing detailed case narrative reports for each health system that are subsequently used in cross-case analyses to develop a contextually rich and detailed understanding of various predetermined and emergent topics. Cross-case analyses will draw on a variety of methodologies, including in-depth case familiarization, inductive or deductive coding, and thematic analysis, to identify cross-cutting themes.

RESULTS

The study team has completed data collection for all 8 participating health systems, including 68 interviews and 1 site visit. We are currently drafting descriptive case narratives, which will be disseminated to participating health systems for member checking and shared broadly as applied vignettes. We are also conducting cross-case analyses to identify critical facilitators and barriers, explore clinician training strategies to facilitate LM implementation, and develop an explanatory model connecting practitioner adoption of LM and experiences of burnout.

CONCLUSIONS

This protocol paper offers real-world insights into research methods and practices to identify barriers and facilitators to the implementation of LM in health systems. Findings can advise LM implementation across various health system contexts. Methodological limitations and lessons learned can guide the execution of other studies with similar methodologies.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/51562.

American College of Lifestyle Medicine Expert Consensus Statement: Lifestyle Medicine for Optimal Outcomes in Primary Care

OBJECTIVE

Identify areas of consensus on integrating lifestyle medicine (LM) into primary care to achieve optimal outcomes.

METHODS

Experts in both LM and primary care followed an a priori protocol for developing consensus statements. Using an iterative, online process, panel members expressed levels of agreement with statements, resulting in classification as consensus, near consensus, or no consensus.

RESULTS

The panel identified 124 candidate statements addressing: (1) Integration into Primary Care, (2) Delivery Models, (3) Provider Education, (4) Evidence-base for LM, (5) Vital Signs, (6) Treatment, (7) Resource Referral and Reimbursement, (8) Patient, Family, and Community Involvement; Shared Decision-Making, (9) Social Determinants of Health and Health Equity, and (10) Barriers to LM. After three iterations of an online Delphi survey, statement revisions, and removal of duplicative statements, 65 statements met criteria for consensus, 24 for near consensus, and 35 for no consensus. Consensus was reached on key topics that included LM being recognized as an essential component of primary care in patients of all ages, including LM as a foundational element of health professional education.

CONCLUSION

The practice of LM in primary care can be strengthened by applying these statements to improve quality of care, inform policy, and identify areas for future research.

Lifestyle Medicine Practitioners Implementing a Greater Proportion of Lifestyle Medicine Experience Less Burnout

PURPOSE

To identify reasons for burnout, characterize the effect of lifestyle medicine (LM) practice on burnout, and assess the risk of burnout in relation to the proportion of LM practice.

DESIGN

Analysis of mixed methods data from a large, cross-sectional survey on LM practice.

SETTING

Web-based survey platform.

PARTICIPANTS

Members of an LM medical professional society at the time of survey administration.

METHODS

Practitioner members of a medical professional society were recruited to a cross-sectional, online survey. Data were collected on LM practice and experiences with burnout. Free-text data were thematically grouped and counted, and the association of burnout with the proportion of lifestyle-based medical practice was analyzed using logistic regression.

RESULTS

Of 482 respondents, 58% reported currently feeling burned out, 28% used to feel burned out but no longer do, and 90% reported LM had positively impacted their professional satisfaction. Among LM practitioners surveyed, practicing more LM was associated with a 43% decrease (0.569; 95% CI: 0.384, 0.845; P = 0.0051) in the odds of experiencing burnout. Top reasons for positive impact included professional satisfaction, sense of accomplishment, and meaningfulness (44%); improved patient outcomes and patient satisfaction (26%); enjoyment of teaching/coaching and engaging in relationships (22%); and helps me personally: quality of life and stress (22%).

CONCLUSION

Implementing LM as a greater proportion of medical practice was associated with lower likelihood of burnout among LM practitioners. Results suggest that increased feelings of accomplishment due to improved patient outcomes and reduced depersonalization contribute to reduced burnout.

Commonalities among dietary recommendations from 2010-2021 clinical practice guidelines: A meta-epidemiological study from the American College of Lifestyle Medicine

Clinical practice guidelines (CPGs) provide recommendations to clinicians based on current medical knowledge to guide and reduce variability in clinical care. With advances in nutrition science research, CPGs increasingly include dietary guidance; however, the degree of consistency in dietary recommendations across CPGs has not been investigated. Using a systematic review approach adapted for meta-epidemiological research, this study compared dietary guidance from current guidelines developed by governments, major medical professional societies, and large health stakeholder associations due to their often well-defined and standardized processes for guideline development. CPGs making recommendations for dietary patterns and food groups or components for generally healthy adults or those with pre-specified chronic diseases were eligible. Literature from January 2010-2022 was searched in five bibliographic databases and augmented by searches in point-of-care resource databases and relevant websites. Reporting followed an adapted Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement and included narrative synthesis and summary tables. The protocol was pre-published on PROSPERO (CRD42021226281). Seventy-eight CPGs for major chronic conditions (autoimmune=7, cancers=5, cardiovascular-related=35, digestive=11, diabetes=12, weight-related=4, or multiple=3) and general health promotion (n=1) were included. Nearly all (91%) made dietary pattern recommendations, and roughly half (49%) endorsed patterns centered around plant foods. Overall, CPGs were most closely aligned in promoting consumption of major plant food groups (vegetables=74% of CPGs, fruit=69%, whole grains=58%) while discouraging intake of alcohol (62%) and salt or sodium (56%). CVD and diabetes CPGs were similarly aligned with additional messaging to consume legumes/pulses (60% of CVD CPGs; 75%, diabetes), nuts and seeds (67%, CVD), and low-fat dairy (60%, CVD). Diabetes guidelines discouraged sweets/added sugars (67%) and sweetened beverages (58%). This alignment across CPGs should boost clinician confidence in relaying such dietary guidance to patients in accordance with their relevant CPGs.

A Six-Week Follow-Up Study on the Sustained Effects of Prolonged Water-Only Fasting and Refeeding on Markers of Cardiometabolic Risk

(1) Background: Chronic inflammation and insulin resistance are associated with cardiometabolic diseases, such as cardiovascular disease, type 2 diabetes mellitus, and non-alcoholic fatty liver disease. Therapeutic water-only fasting and whole-plant-food refeeding was previously shown to improve markers of cardiometabolic risk and may be an effective preventative treatment but sustained outcomes are unknown. We conducted a single-arm, open-label, observational study with a six-week post-treatment follow-up visit to assess the effects of water-only fasting and refeeding on markers of cardiometabolic risk. (2) Methods: Patients who had voluntarily elected and were approved to complete a water-only fast were recruited from a single-center residential medical facility. The primary endpoint was to describe changes to Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) scores between the end-of-refeed visit and the six-week follow-up visit. Additionally, we report on changes in anthropometric measures, blood lipids, high-sensitivity C-reactive protein (hsCRP), and fatty liver index (FLI). Observations were made at baseline, end-of-fast (EOF), end-of-refeed (EOR), and six-week follow-up (FU). (3) Results: The study enrolled 40 overweight/obese non-diabetic participants, of which 33 completed the full study protocol. Median fasting, refeeding, and follow-up lengths were 14, 6, and 45 days, respectively. At the FU visit, body weight (BW), body mass index (BMI), abdominal circumference (AC), systolic blood pressure (SBP), diastolic blood pressure (DBP), total cholesterol (TC), low-density lipoprotein (LDL), hsCRP, and FLI were significantly decreased from baseline. Triglycerides (TG) and HOMA-IR scores, which had increased at EOR, returned to baseline values at the FU visit. (4) Conclusion: Water-only fasting and whole-plant-food refeeding demonstrate potential for long-term improvements in markers of cardiovascular risk including BW, BMI, AC, SBP, DBP, blood lipids, FLI, and hsCRP.

Medication Deprescribing Among Patients With Type 2 Diabetes: A Qualitative Case Series of Lifestyle Medicine Practitioner Protocols

This study is a qualitative case series of lifestyle medicine practitioners’ protocols for medication de-escalation in the context of reduced need for glucose-lowering medications due to lifestyle modifications. Increasing numbers of lifestyle medicine practitioners report achieving reductions in medications among patients with type 2 diabetes, and in some cases remission, but limited data exist on the clinical decision-making process used to determine when and how medications are deprescribed. Practitioners interviewed here provide accounts of their deprescribing protocols. This information can serve as pilot data for other practitioners seeking examples of how deprescribing in the context of lifestyle medicine treatment is conducted.

Dietary Interventions to Treat Type 2 Diabetes in Adults with a Goal of Remission: An Expert Consensus Statement from the American College of Lifestyle Medicine

Objective

The objective of this Expert Consensus Statement is to assist clinicians in achieving remission of type 2 diabetes (T2D) in adults using diet as a primary intervention. Evidence-informed statements agreed upon by a multi-disciplinary panel of expert healthcare professionals were used.

Methods

Panel members with expertise in diabetes treatment, research, and remission followed an established methodology for developing consensus statements using a modified Delphi process. A search strategist systematically reviewed the literature, and the best available evidence was used to compose statements regarding dietary interventions in adults 18 years and older diagnosed with T2D. Topics with significant practice variation and those that would result in remission of T2D were prioritized. Using an iterative, online process, panel members expressed levels of agreement with the statements, resulting in classification as consensus, near-consensus, or non-consensus based on mean responses and the number of outliers.

Results

The expert panel identified 131 candidate consensus statements that focused on addressing the following high-yield topics: (1) definitions and basic concepts; (2) diet and remission of T2D; (3) dietary specifics and types of diets; (4) adjuvant and alternative interventions; (5) support, monitoring, and adherence to therapy; (6) weight loss; and (7) payment and policy. After 4 iterations of the Delphi survey and removal of duplicative statements, 69 statements met the criteria for consensus, 5 were designated as near consensus, and 60 were designated as no consensus. In addition, the consensus was reached on the following key issues: (a) Remission of T2D should be defined as HbA1c <6.5% for at least 3 months with no surgery, devices, or active pharmacologic therapy for the specific purpose of lowering blood glucose; (b) diet as a primary intervention for T2D can achieve remission in many adults with T2D and is related to the intensity of the intervention; and (c) diet as a primary intervention for T2D is most effective in achieving remission when emphasizing whole, plant-based foods with minimal consumption of meat and other animal products. Many additional statements that achieved consensus are highlighted in a tabular presentation in the manuscript and elaborated upon in the discussion section.

Conclusion

Expert consensus was achieved for 69 statements pertaining to diet and remission of T2D, dietary specifics and types of diets, adjuvant and alternative interventions, support, monitoring, adherence to therapy, weight loss, and payment and policy. Clinicians can use these statements to improve quality of care, inform policy and protocols, and identify areas of uncertainty.

Lifestyle Medicine Reimbursement: A Proposal for Policy Priorities Informed by a Cross-Sectional Survey of Lifestyle Medicine Practitioners

Lifestyle medicine (LM) is a rapidly emerging clinical discipline that focuses on intensive therapeutic lifestyle changes to treat chronic disease, often producing dramatic health benefits. In spite of these well-documented benefits of LM approaches to provide evidence-based care that follows current clinical guidelines, LM practitioners have found reimbursement challenging. The objectives of this paper are to present the results of a cross-sectional survey of LM practitioners regarding lifestyle medicine reimbursement and to propose policy priorities related to the ability of practitioners to implement and achieve reimbursement for these necessary services. Results from a closed, online survey in 2019 were analyzed, with a total of n = 857 included in this analysis. Results were descriptively analyzed. This manuscript articulates policy proposals informed by the survey results. The study sample was 58% female, with median age of 51. A minority of the sample (17%) reported that all their practice was LM, while 56% reported that some of their practice was LM. A total of 55% of practitioners reported not being able to receive reimbursement for LM practice. Of those survey respondents who provided an answer to the question of what would make the practice of LM easier (n = 471), the following suggestions were offered: reimbursement overall (18%), reimbursement for more time spent with patients (17%), more support from leadership (16%), policy measures to incentivize health (13%), education in LM for practitioners (11%), LM-specific billing codes and billing knowledge along with better electronic medical record (EMR) capabilities and streamlined reporting/paperwork (11%), and reimbursement for the extended care team (10%). Proposed policy changes focus on three areas of focus: (1) support for the care process using a LM approach, (2) reimbursement emphasizing outcomes of health, patient experience, and delivering person-centered care, and (3) incentivizing treatment that produces disease remission/reversal. Rectifying reimbursement barriers to lifestyle medicine practice will require a sustained effort from health systems and policy makers. The urgency of this transition towards lifestyle medicine interventions to effectively address the epidemic of chronic diseases in a way that can significantly improve outcomes is being hindered by current reimbursement policies and models.

Lifestyle Medicine and Economics: A Proposal for Research Priorities Informed by a Case Series of Disease Reversal

Chronic disease places an enormous economic burden on both individuals and the healthcare system, and existing fee-for-service models of healthcare prioritize symptom management, medications, and procedures over treating the root causes of disease through changing health behaviors. Value-based care is gaining traction, and there is a need for value-based care models that achieve the quadruple aim of (1) improved population health, (2) enhanced patient experience, (3) reduced healthcare costs, and (4) improved work life and decreased burnout of healthcare providers. Lifestyle medicine (LM) has the potential to achieve these four aims, including promoting health and wellness and reducing healthcare costs; however, the economic outcomes of LM approaches need to be better quantified in research. This paper demonstrates proof of concept by detailing four cases that utilized an intensive, therapeutic lifestyle intervention change (ITLC) to dramatically reverse disease and reduce healthcare costs. In addition, priorities for lifestyle medicine economic research related to the components of quadruple aim are proposed, including conducting rigorously designed research studies to adequately measure the effects of ITLC interventions, modeling the potential economic cost savings enabled by health improvements following lifestyle interventions as compared to usual disease progression and management, and examining the effects of lifestyle medicine implementation upon different payment models.

Using Evidence Mapping to Examine Motivations for Following Plant-Based Diets

Motivations to adopt plant-based diets are of great public health interest. We used evidence mapping to identify methods that capture motivations to follow plant-based diets and summarize demographic trends in dietary motivations. We identified 56 publications that described 90 samples of plant-based diet followers and their dietary motivations. We categorized the samples by type of plant-based diet: vegan (19%), vegetarian (33%), semivegetarian (24%), and other, unspecified plant-based diet followers (23%). Of 90 studies examined, 31% administered multiple-choice questions to capture motivations, followed by rate items (23%), Food Choice Questionnaire (17%), free response (9%), and rank choices (10%). Commonly reported motivations were health, sensory/taste/disgust, animal welfare, environmental concern, and weight loss. The methodological variation highlights the importance of using a structured questionnaire to investigate dietary motivations in epidemiological studies. Motivations among plant-based diet followers appear distinct, but evidence on the association between age and motivations appears limited.

Theoretical Food and Nutrient Composition of Whole-Food Plant-Based and Vegan Diets Compared to Current Dietary Recommendations

Public interest in popular diets is increasing, in particular whole-food plant-based (WFPB) and vegan diets. Whether these diets, as theoretically implemented, meet current food-based and nutrient-based recommendations has not been evaluated in detail. Self-identified WFPB and vegan diet followers in the Adhering to Dietary Approaches for Personal Taste (ADAPT) Feasibility Survey reported their most frequently used sources of information on nutrition and cooking. Thirty representative days of meal plans were created for each diet. Weighted mean food group and nutrient levels were calculated using the Nutrition Data System for Research (NDSR) and data were compared to DRIs and/or USDA Dietary Guidelines/MyPlate meal plan recommendations. The calculated HEI-2015 scores were 88 out of 100 for both WFPB and vegan meal plans. Because of similar nutrient composition, only WFPB results are presented. In comparison to MyPlate, WFPB meal plans provide more total vegetables (180%), green leafy vegetables (238%), legumes (460%), whole fruit (100%), whole grains (132%), and less refined grains (−74%). Fiber level exceeds the adequate intakes (AI) across all age groups. WFPB meal plans failed to meet the Recommended Dietary Allowances (RDA)s for vitamin B12 and D without supplementation, as well as the RDA for calcium for women aged 51–70. Individuals who adhere to WFBP meal plans would have higher overall dietary quality as defined by the HEI-2015 score as compared to typical US intakes with the exceptions of calcium for older women and vitamins B12 and D without supplementation. Future research should compare actual self-reported dietary intakes to theoretical targets.

Web-Based Recruitment and Survey Methodology to Maximize Response Rates from Followers of Popular Diets: the Adhering to Dietary Approaches for Personal Taste (ADAPT) Feasibility Survey

BACKGROUND

Although there is interest in popular diets such as vegan and vegetarian, Paleo, and other "whole food" diets, existing cohort studies lack data for these subgroups. The use of electronic data capture and Web-based surveys in nutrition research may be valuable for future studies by allowing targeting of specific dietary subgroups.

OBJECTIVE

The aim was to perform a Feasibility Survey (FS) to assess the practicality of Web-based research methods to gather data and to maximize response rates among followers of popular diets.

METHODS

The FS was an open, voluntary, 15-min survey conducted over 8 wk in the summer of 2015. Recruitment targeted self-identified followers of popular diets from a convenience sample, offering no incentives, via social media and e-newsletters shared by recruitment partners. Feasibility was assessed by number of responses, survey completion rate, distribution of diets, geographic location, and willingness to participate in future research.

RESULTS

A total of 14,003 surveys were initiated; 13,787 individuals consented, and 9726 completed the survey (71% of consented). The numbers of unique visitors to the questionnaire site, view rate, and participation rate were not captured. Among respondents with complete demographic data, 83% were female and 93% were white. Diet designations were collapsed into the following groups: whole-food, plant-based (25%); vegan and raw vegan (19%); Paleo (14%); try to eat healthy (11%); vegetarian and pescatarian (9%); whole food (8%); Weston A Price (5%); and low-carbohydrate (low-carb) (4%). Forced-response, multiple-choice questions produced the highest response rates (0-2% selected "prefer not to answer"). The percentage who were willing to complete future online questionnaires was 86%, diet recall was 93%, and food diary was 75%; the percentages willing to provide a finger-stick blood sample, venipuncture blood sample, urine sample, and stool sample were 60%, 44%, 58%, and 42%, respectively.

CONCLUSIONS

This survey suggests that recruiting followers of popular diets is feasible with the use of Web-based methods. The unbalanced sample with respect to sex and race/ethnicity could be corrected with specific recruitment strategies using targeted online marketing techniques.

Animal versus plant protein and adult bone health: A systematic review and meta-analysis from the National Osteoporosis Foundation

Background

Protein may have both beneficial and detrimental effects on bone health depending on a variety of factors, including protein source.

Objective

The aim was to conduct a systematic review and meta-analysis evaluating the effects of animal versus plant protein intake on bone mineral density (BMD), bone mineral content (BMC) and select bone biomarkers in healthy adults.

Methods

Searches across five databases were conducted through 10/31/16 for randomized controlled trials (RCTs) and prospective cohort studies in healthy adults that examined the effects of animal versus plant protein intake on 1) total body (TB), total hip (TH), lumbar spine (LS) or femoral neck (FN) BMD or TB BMC for at least one year, or 2) select bone formation and resorption biomarkers for at least six months. Strength of evidence (SOE) was assessed and random effect meta-analyses were performed.

Results

Seven RCTs examining animal vs. isoflavone-rich soy (Soy+) protein intake in 633 healthy peri-menopausal (n = 1) and post-menopausal (n = 6) women were included. Overall risk of bias was medium. Limited SOE suggests no significant difference between Soy+ vs. animal protein on LS, TH, FN and TB BMD, TB BMC, and bone turnover markers BSAP and NTX. Meta-analysis results showed on average, the differences between Soy+ and animal protein groups were close to zero and not significant for BMD outcomes (LS: n = 4, pooled net % change: 0.24%, 95% CI: -0.80%, 1.28%; TB: n = 3, -0.24%, 95% CI: -0.81%, 0.33%; FN: n = 3, 0.13%, 95% CI: -0.94%, 1.21%). All meta-analyses had no statistical heterogeneity.

Conclusions

These results do not support soy protein consumption as more advantageous than animal protein, or vice versa. Future studies are needed examining the effects of different protein sources in different populations on BMD, BMC, and fracture.

Dietary protein and bone health: a systematic review and meta-analysis from the National Osteoporosis Foundation

Background: Considerable attention has recently focused on dietary protein's role in the mature skeleton, prompted partly by an interest in nonpharmacologic approaches to maintain skeletal health in adult life.Objective: The aim was to conduct a systematic review and meta-analysis evaluating the effects of dietary protein intake alone and with calcium with or without vitamin D (Ca±D) on bone health measures in adults.Design: Searches across 5 databases were conducted through October 2016 including randomized controlled trials (RCTs) and prospective cohort studies examining 1) the effects of "high versus low" protein intake or 2) dietary protein's synergistic effect with Ca±D intake on bone health outcomes. Two investigators independently conducted abstract and full-text screenings, data extractions, and risk of bias (ROB) assessments. Strength of evidence was rated by group consensus. Random-effects meta-analyses for outcomes with ≥4 RCTs were performed.Results: Sixteen RCTs and 20 prospective cohort studies were included in the systematic review. Overall ROB was medium. Moderate evidence suggested that higher protein intake may have a protective effect on lumbar spine (LS) bone mineral density (BMD) compared with lower protein intake (net percentage change: 0.52%; 95% CI: 0.06%, 0.97%, I²: 0%; n = 5) but no effect on total hip (TH), femoral neck (FN), or total body BMD or bone biomarkers. Limited evidence did not support an effect of protein with Ca±D on LS BMD, TH BMD, or forearm fractures; there was insufficient evidence for FN BMD and overall fractures.Conclusions: Current evidence shows no adverse effects of higher protein intakes. Although there were positive trends on BMD at most bone sites, only the LS showed moderate evidence to support benefits of higher protein intake. Studies were heterogeneous, and confounding could not be excluded. High-quality, long-term studies are needed to clarify dietary protein's role in bone health. This trial was registered at www.crd.york.ac.uk as CRD42015017751.

Potential link between excess added sugar intake and ectopic fat: a systematic review of randomized controlled trials

CONTEXT

The effect of added sugar intake on ectopic fat accumulation is a subject of debate.

OBJECTIVE

A systematic review and meta-analysis of randomized controlled trials (RCTs) was conducted to examine the potential effect of added sugar intake on ectopic fat depots.

DATA SOURCES

MEDLINE, CAB Abstracts, CAB Global Health, and EBM (Evidence-Based Medicine) Reviews - Cochrane Central Register of Controlled Trials databases were searched for studies published from 1973 to September 2014.

DATA EXTRACTION

RCTs with a minimum of 6 days' duration of added sugar exposure in the intervention group were selected. The dosage of added sugar intake as a percentage of total energy was extracted or calculated. Means and standard deviations of pre- and post-test measurements or changes in ectopic fat depots were collected.

DATA SYNTHESIS

Fourteen RCTs were included. Most of the studies had a medium to high risk of bias. Meta-analysis showed that, compared with eucaloric controls, subjects who consumed added sugar under hypercaloric conditions likely increased ectopic fat, particularly in the liver (pooled standardized mean difference = 0.9 [95%CI, 0.6-1.2], n = 6) and muscles (pooled SMD = 0.6 [95%CI, 0.2-1.0], n = 4). No significant difference was observed in liver fat, visceral adipose tissue, or muscle fat when isocaloric intakes of different sources of added sugars were compared.

CONCLUSIONS

Data from a limited number of RCTs suggest that excess added sugar intake under hypercaloric diet conditions likely increases ectopic fat depots, particularly in the liver and in muscle fat. There are insufficient data to compare the effect of different sources of added sugars on ectopic fat deposition or to compare intake of added sugar with intakes of other macronutrients. Future well-designed RCTs with sufficient power and duration are needed to address the role of sugars on ectopic fat deposition.