Elizabeth Delbridge

The effect of rate of weight loss on long-term weight management: a randomised controlled trial

BACKGROUND Guidelines recommend gradual weight loss for the treatment of obesity, indicative of a widely held opinion that weight lost rapidly is more quickly regained. We aimed to investigate the effect of the rate of weight loss on the rate of regain in obese people. METHODS For this two phase, randomised, non-masked, dietary intervention trial in a Melbourne metropolitan hospital, we enrolled 204 participants (51 men and 153 women) aged 18–70 years with a BMI between 30 and 45 kg/m2. During phase 1, we randomly assigned (1:1) participants with a block design (block sizes of 2, 4, and 6) to account for sex, age, and BMI, to either a 12-week rapid weight loss or a 36-week gradual programme, both aimed at 15% weight loss. We placed participants who lost 12·5% or more weight during phase 1 on a weight maintenance diet for 144 weeks (phase 2). The primary outcome was mean weight loss maintained at week 144 of phase 2. We investigated the primary outcome by both completers only and intention-to-treat analyses. This study is registered with the Australian New Zealand Clinical Trials Registry, number ACTRN12611000190909. FINDINGS 200 participants were randomly assigned to the gradual weight loss (n=103) or rapid weight loss (n=97) programme between Aug 8, 2008, and March 9, 2010. After phase 1, 51 (50%) participants in the gradual weight loss group and 76 (81%) in the rapid weight loss group achieved 12·5% or more weight loss in the allocated time and started phase 2. At the end of phase 2, both gradual weight loss and rapid weight loss participants who completed the study (n=43 in gradual weight loss and n=61 in rapid weight loss) had regained most of their lost weight (gradual weight loss 71·2% regain, 95% CI 58·1–84·3 vs rapid weight loss 70·5%, 57·8–83·2). Intention-to-treat analysis showed similar results (gradual weight loss 76·3% regain, 95% CI 65·2–87·4 vs rapid weight loss 76·3%, 65·8–86·8). In phase 1, one participant in the rapid weight loss group developed cholecystitis, requiring cholecystectomy. In phase 2, two participants in the rapid weight loss group developed cancer. INTERPRETATION The rate of weight loss does not affect the proportion of weight regained within 144 weeks. These findings are not consistent with present dietary guidelines which recommend gradual over rapid weight loss, based on the belief that rapid weight loss is more quickly regained. FUNDING The Australian National Health and Medical Research Council and the Sir Edward Dunlop Medical Research Foundation.

One-year weight maintenance after significant weight loss in healthy overweight and obese subjects: does diet composition matter?

BACKGROUND For many people, maintenance of weight loss is elusive. Whereas high-protein (HP) diets have been found to be superior to high-carbohydrate (HC) diets for weight loss in the short term, their benefits long term are unclear, particularly for weight maintenance. Furthermore, the literature lacks consensus on the long-term effects of an HP diet on cardiovascular disease risk factors. OBJECTIVE The objective was to investigate whether macronutrient dietary composition plays a role in weight maintenance and in improvement of cardiovascular disease risk factors. DESIGN The study comprised 2 phases. Phase 1 featured a very-low-energy diet for 3 mo. In phase 2, the subjects were randomly assigned to an HP or an HC diet for 12 mo. The diets were isocaloric, tightly controlled, and individually prescribed for weight maintenance. The subjects were overweight or obese but otherwise healthy men and women. RESULTS The subjects lost an average of 16.5 kg during phase 1 and maintained a mean (+/-SEM) weight loss of 14.5 +/- 1.2 kg (P < 0.001) during phase 2; no significant differences between groups were observed. By the end of the study, reductions in systolic blood pressure were 14.3 +/- 2.4 mm Hg for the HP group and 7.7 +/- 2.2 mm Hg for the HC group (P < 0.045). Forty-seven percent of the 180 subjects who began the study completed both phases. CONCLUSIONS The results indicate that the protein or carbohydrate content of the diet has no effect on successful weight-loss maintenance. A general linear model analysis indicated that dietary treatment (HP or HC) was a significant factor in systolic blood pressure change and in favor of the HP diet. This trial was registered at www.clinicaltrials.gov as NCT 00625236.

Ketosis and appetite-mediating nutrients and hormones after weight loss

Background/Objectives:Diet-induced weight loss is accompanied by compensatory changes, which increase appetite and encourage weight regain. There is some evidence that ketogenic diets suppress appetite. The objective is to examine the effect of ketosis on a number of circulating factors involved in appetite regulation, following diet-induced weight loss.Subjects/Methods:Of 50 non-diabetic overweight or obese subjects who began the study, 39 completed an 8-week ketogenic very-low-energy diet (VLED), followed by 2 weeks of reintroduction of foods. Following weight loss, circulating concentrations of glucose, insulin, non-esterified fatty acids (NEFA), β-hydroxybutyrate (BHB), leptin, gastrointestinal hormones and subjective ratings of appetite were compared when subjects were ketotic, and after refeeding.Results:During the ketogenic VLED, subjects lost 13% of initial weight and fasting BHB increased from (mean±s.e.m.) 0.07±0.00 to 0.48±0.07 mmol/l (P<0.001). BHB fell to 0.19±0.03 mmol/l after 2 weeks of refeeding (P<0.001 compared with week 8). When participants were ketotic, the weight loss induced increase in ghrelin was suppressed. Glucose and NEFA were higher, and amylin, leptin and subjective ratings of appetite were lower at week 8 than after refeeding.Conclusions:The circulating concentrations of several hormones and nutrients which influence appetite were altered after weight loss induced by a ketogenic diet, compared with after refeeding. The increase in circulating ghrelin and subjective appetite which accompany dietary weight reduction were mitigated when weight-reduced participants were ketotic.