Effect of very low calorie diet on body composition and exercise response in sedentary women

Associations between the proportion of fat-free mass loss during weight loss, changes in appetite, and subsequent weight change: results from a randomized 2-stage dietary intervention trial

BACKGROUND

Dynamic changes in body composition which occur during weight loss may have an influential role on subsequent energy balance behaviors and weight.

OBJECTIVES

The aim of this article is to consider the effect of proportionate changes in body composition during weight loss on subsequent changes in appetite and weight outcomes at 26 wk in individuals engaged in a weight loss maintenance intervention.

METHODS

A subgroup of the Diet, Obesity, and Genes (DiOGenes) study (n = 209) was recruited from 3 European countries. Participants underwent an 8-wk low-calorie diet (LCD) resulting in ≥8% body weight loss, during which changes in body composition (by DXA) and appetite (by visual analog scale appetite perceptions in response to a fixed test meal) were measured. Participants were randomly assigned into 5 weight loss maintenance diets based on protein and glycemic index content and followed up for 26 wk. We investigated associations between proportionate fat-free mass (FFM) loss (%FFML) during weight loss and 1) weight outcomes at 26 wk and 2) changes in appetite perceptions.

RESULTS

During the LCD, participants lost a mean ± SD of 11.2 ± 3.5 kg, of which 30.4% was FFM. After adjustment, there was a tendency for %FFML to predict weight regain in the whole group (β: 0.041; 95% CI: -0.001, 0.08; P = 0.055), which was significant in men (β: 0.09; 95% CI: 0.02, 0.15; P = 0.009) but not women (β: 0.01; 95% CI: -0.04, 0.07; P = 0.69). Associations between %FFML and change in appetite perceptions during weight loss were inconsistent. The strongest observations were in men for hunger (r = 0.69, P = 0.002) and desire to eat (r = 0.61, P = 0.009), with some tendencies in the whole group and no associations in women.

CONCLUSIONS

Our results suggest that composition of weight loss may have functional importance for energy balance regulation, with greater losses of FFM potentially being associated with increased weight regain and appetite. This trial was registered at clinicaltrials.gov as NCT00390637.

Effect of a Whey Protein Supplement on Preservation of Fat Free Mass in Overweight and Obese Individuals on an Energy Restricted Very Low Caloric Diet

The obesity epidemic has caused a widespread interest in strategies to achieve a healthy "high quality" weight loss, where excess fat is lost, while fat free mass (FFM) is preserved. In this study, we aimed to examine the effect of whey protein supplementation given before night sleep on FFM preservation during a 4-week (wk) period on a very low caloric diet (VLCD). Twenty-nine obese subjects (body mass index (BMI) > 28 kg/m²) completed a 4-week intervention including a VLCD and a walking program (30 min walking × 5 times per week). Subjects were randomly assigned to either control (CON, n = 15) or a whey protein supplement (PRO, 0.4 g protein/kg/day, n = 14), ingested before bedtime. Body composition (dual-energy X-ray absorptiometry, DXA), blood analysis and physical test were performed pre and post intervention. We measured nitrogen excretion in three 24 h urine collections (Day 0, 7 and 28) to assess nitrogen balance. Changes in nitrogen balance (NB) after 7 and 28 days was different between treatment groups (interaction p < 0.05). PRO was in NB after 7 days and in positive NB at day 28. In contrast, CON was in negative NB at day 7, but in NB at day 28. Nevertheless, no significant group differences were observed in the change in pre- and post-FFM measurements (-2.5 kg, [95% CI: 1.9; 3.1], p = 0.65). In conclusion, ingestion of a whey protein supplement before bedtime during a 4-week period on a VLCD improved nitrogen balance, but did not lead to any significant improvement in the quality of the weight loss in regard to observed changes in body composition and health parameters compared with controls.

Exercise Preserves Lean Mass and Performance during Severe Energy Deficit: The Role of Exercise Volume and Dietary Protein Content

The loss of fat-free mass (FFM) caused by very-low-calorie diets (VLCD) can be attenuated by exercise. The aim of this study was to determine the role played by exercise and dietary protein content in preserving the lean mass and performance of exercised and non-exercised muscles, during a short period of extreme energy deficit (~23 MJ deficit/day). Fifteen overweight men underwent three consecutive experimental phases: baseline assessment (PRE), followed by 4 days of caloric restriction and exercise (CRE) and then 3 days on a control diet combined with reduced exercise (CD). During CRE, the participants ingested a VLCD and performed 45 min of one-arm cranking followed by 8 h walking each day. The VLCD consisted of 0.8 g/kg body weight/day of either whey protein (PRO, n = 8) or sucrose (SU, n = 7). FFM was reduced after CRE (P < 0.001), with the legs and the exercised arm losing proportionally less FFM than the control arm [57% (P < 0.05) and 29% (P = 0.05), respectively]. Performance during leg pedaling, as reflected by the peak oxygen uptake and power output (Wpeak), was reduced after CRE by 15 and 12%, respectively (P < 0.05), and recovered only partially after CD. The deterioration of cycling performance was more pronounced in the whey protein than sucrose group (P < 0.05). Wpeak during arm cranking was unchanged in the control arm, but improved in the contralateral arm by arm cranking. There was a linear relationship between the reduction in whole-body FFM between PRE and CRE and the changes in the cortisol/free testosterone ratio (C/FT), serum isoleucine, leucine, tryptophan, valine, BCAA, and EAA (r = −0.54 to −0.71, respectively, P < 0.05). C/FT tended to be higher in the PRO than the SU group following CRE (P = 0.06). In conclusion, concomitant low-intensity exercise such as walking or arm cranking even during an extreme energy deficit results in remarkable preservation of lean mass. The intake of proteins alone may be associated with greater cortisol/free testosterone ratio and is not better than the ingestion of only carbohydrates for preserving FFM and muscle performance in interventions of short duration.

Effect of diet-induced weight loss on muscle strength in adults with overweight or obesity - a systematic review and meta-analysis of clinical trials

We conducted a systematic review and meta-analysis to identify how diet-induced weight loss in adults with overweight or obesity impacts on muscle strength. Twenty-seven publications, including 33 interventions, most of which were 8-24 weeks in duration, were included. Meta-analysis of seven interventions measuring knee extensor strength by isokinetic dynamometry in 108 participants found a significant decrease following diet-induced weight loss (-9.0 [95% confidence interval: -13.8, -4.1] N/m, P < 0.001), representing a 7.5% decrease from baseline values. Meta-analysis of handgrip strength from 10 interventions in 231 participants showed a non-significant decrease (-1.7 [-3.6, 0.1] kg, P = 0.070), with significant heterogeneity (I(2)  = 83.9%, P < 0.001). This heterogeneity may have been due to diet type, because there was a significant decrease in handgrip strength in seven interventions in 169 participants involving moderate energy restriction (-2.4 [-4.8, -0.0] kg, P = 0.046), representing a 4.6% decrease from baseline values, but not in three interventions in 62 participants involving very-low-energy diet (-0.4 [-2.0, 1.2] kg, P = 0.610). Because of variability in methodology and muscles tested, no other data could be meta-analyzed, and qualitative assessment of the remaining interventions revealed mixed results. Despite varying methodologies, diets and small sample sizes, these findings suggest a potential adverse effect of diet-induced weight loss on muscle strength. While these findings should not act as a deterrent against weight loss, due to the known health benefits of losing excess weight, they call for strategies to combat strength loss - such as weight training and other exercises - during diet-induced weight loss. © 2016 World Obesity.

Changes in body composition with weight loss: obese subjects randomized to surgical and medical programs

OBJECTIVE

To assess changes in body composition with weight loss in obese subjects randomized to a laparoscopic adjustable gastric band surgical program or a medical program using a very-low-energy diet and orlistat.

RESEARCH METHODS AND PROCEDURES

Using body composition measurements by DXA, neutron activation for total body nitrogen, and whole body gamma counting for total body potassium, we studied changes in fat mass, fat distribution, fat-free mass, total bone mineral content, total body protein, and body cell mass at 6 (n = 61 paired) and 24 months (n = 53 paired) after randomization.

RESULTS

At 24 months, the surgical group had lost significantly more weight (surgical, 20.3 +/- 6.5 kg; medical, 5.9 +/- 8.0 kg). There was favorable fat-free mass to fat mass loss ratios for both groups (surgical, 1:5.5; medical, 1:5.9). Changes in total body nitrogen or potassium were favorable in each group. A small reduction in mean bone mineral content occurred throughout the study but was not associated with extent of weight loss or treatment group. At 6 months, weight loss for both groups was similar (surgical, 14.1 +/- 4.5 kg; medical, 13.3 +/- 7.3 kg). The medical program subjects lost less fat-free mass and skeletal muscle and had increased total body protein. The proportion of body fat to limb fat remained remarkably constant throughout the study.

DISCUSSION

Weight loss programs used in this study induced fat loss without significant deleterious effects on the components of fat-free mass.

Changes in fat-free mass during significant weight loss: a systematic review

OBJECTIVE

To identify the proportion of weight lost as fat-free mass (FFM) by various weight loss interventions.

METHODS

Medline and Embase were systematically searched for reliable measurements of FFM before and after weight loss of >10 kg and eligible data were pooled. In a fixed effect model of % FFM loss/weight loss (%FFML), linear regression analysis was used to determine the influence of degree of caloric restriction, exercise, magnitude of weight loss, initial body mass index (BMI) and type of surgery.

RESULTS

Data were included from 26 cohorts treated with dietary and behavioral interventions and 29 cohorts of bariatric surgery patients. The degree of caloric restriction was positively associated with %FFML (r (2)=0.31, P=0.006) and in three randomized controlled trials exercise was shown to decrease %FFML. Compared with laparoscopic adjustable gastric banding (LAGB), biliopancreatic diversion (BPD) and roux en Y gastric bypass (RYGB) caused greater log(e) (natural log) %FFML (r (2)=0.453, P<0.001). Differences in log(e) %FFML between surgical procedures were independent of initial BMI and magnitude of weight loss.

CONCLUSIONS

The degree of caloric restriction, exercise and rate of weight loss influence the proportion of weight lost as FFM after non-surgical interventions. For surgical interventions, BPD and RYGB result in greater %FFML than LAGB.

Stages in the development of a research project: putting the idea together

We have considered some of the most important factors involved in designing a viable study that will adequately address the research question. Although we do not profess to be experts in all aspects of the above, we have learned through experience that attention to many of the above points will help to avoid frustration during the experimental process and when the study is presented for external review and subsequent presentation and publication. Good luck in your research.