Slow and Steady May Not Win the Race for Weight Loss Maintenance

Study Overview

Objective. To compare weight regain after rapid versus slower loss of an equivalent amount of weight.

Study design. Randomized clinical trial.

Setting and participants. This study took place in a single medical center in the Netherlands. Investigators recruited 61 adults (no age range provided) with body mass index (BMI) between 28–35 kg/m² and at a stable weight (no change of > 3 kg for the past 2 months) to participate in a weight loss study. Individuals with type 2 diabetes, dyslipidemia, uncontrolled hypertension, or liver, heart or kidney disease were excluded, as were those who were currently pregnant or reported consuming more than moderate amounts of alcohol.

Once consented, participants were randomized into one of 2 study arms. The rapid weight loss arm was prescribed a very-low-calorie diet (VLCD) with just 500 kcal/day (43% protein/43% carb/14% fat) for 5 weeks, after which they transitioned to a 4-week “weight stable” period, and then a 9-month follow-up period (overall follow-up time of ~11 months; 10 months after weight loss). In contrast, the slower weight loss arm was prescribed a low-calorie diet (LCD) with 1250 kcal/day (29% protein/48% carb/23% fat) for 12 weeks, after which they also transitioned to a 4-week weight stable period and 9 months of follow-up (overall follow-up time of ~13 months; 10 months after weight loss). VLCD (rapid weight loss) participants received 3 meal replacement shakes per day (totaling 500 kcal) during the weight loss period and were also told they could consume unlimited amounts of low-calorie vegetables. The LCD (slower weight loss) participants received 1 meal replacement shake per day during their 12 weeks of weight loss and were responsible for providing the remainder of their own meals and snacks according to guidelines from a study dietitian. Following active weight loss, both groups then shifted to higher-calorie, food-based diets during a “weight stable” 4-week period and were responsible during this time for providing all of their own food. The researchers do not specify the details of the diet composition for this weight stable period. Exposure to the registered dietitian was the same in both groups, with 5 consultations during weight loss (weekly for VLCD, presumably more spaced out for LCD) and 4 during weight stable period. No further diet advice or meal replacement support was given during the 9-month follow-up period, but participants came in for monthly weigh-ins.

Main outcome measure. The primary outcome measure was change in weight (ie, amount of weight regained) during the 9-month follow-up period, compared between groups using an independent samples t test. Additional biometric measures included change in waist circumference and changes in body composition. For the latter, the researchers used a “Bod Pod” to conduct air-displacement plethysmography and determine what percentage of an individual’s weight was fat mass (FM) versus lean mass/water (FFM [fat-free mass]). They then compared the amount of FFM lost between groups, again using the independent samples t test.

The researchers also collected information on self-reported physical activity (questionnaire) and self-reported history of weight cycling (number of times a participant had previously lost and regained at least 5 kg) prior to this study. These were not outcomes per-se, but were collected so that they could be examined as correlates of the biometric outcomes above, using Pearson and Spearman’s correlation coefficients.

Results. The LCD (n = 29) and VLCD (n = 28) groups were similar at baseline with no significant differences reported. Of the 61 individuals initially enrolled, 57 (93%) completed the study. Summary statistics are reported only for these 57 individuals. No imputation or other methods for handling missing data were used. There were slightly more women than men in the study (53% women); the average (SD) age was 51.8 (1.9) years in the LCD group and 50.7 (1.5) years in the VLCD group. Mean starting BMI was 31 kg/m² (31.3 [0.5] in LCD, 31.0 [0.4] in VLCD) and both groups had just under 40% body fat at baseline (39.9% [1.8] in LCD, 39.7% [1.5] in VLCD).

After 12 weeks of weight loss for LCD, or 5 weeks of weight loss for VLCD, both groups lost a similar amount of total weight (8.2 [0.5] kg in LCD vs. 9.0 [0.4] kg in VLCD), then had no significant changes in weight during the subsequent 4-week “weight stable” period. However, during the weight stable period VLCD patients had an average 0.8 (0.6) cm increase in waist circumference (a rebounding after a decrease of 7.7 cm during weight loss), while LCD patients on average had a continued decrease of 1.0 (0.5 cm) in waist circumference (P = 0.003).

There was no significant difference between groups for the primary outcome of weight regain during 9-months of follow-up (4.2 [0.6] kg regained for LCD, 4.5 [0.7] for VLCD; P = 0.73). The only significant correlates of weight regain were amount of FFM lost (more lean mass lost predicted more weight regain), and amount of physical activity reported during follow-up (more activity predicted less regain). Participant sex, age, starting BMI, history of weight cycling, and amount of weight lost did not correlate with rate of re-gain.

One area where there was a significant between-group difference, both after initial weight loss and persisting after the weight stable period, was in the amount of FFM lost (a rough approximation of lost lean mass, eg, muscle mass). VLCD participants had more FFM loss (1.6 [0.2] kg) than LCD participants (0.6 [0.2] kg) (P < 0.01) after active weight loss, and continued to have significantly more FFM loss (0.8 [0.2] kg vs. 0.2 [0.2] kg) after the 4-week weight stable period.

There were no between-group differences at the end of weight loss or at the end of follow-up for hip or waist circumference or for blood pressure.

Conclusion. The authors conclude that rate of weight loss does not affect one’s risk of weight regain after a diet, after a similar amount of weight has been lost.