Summary:
Weight loss maintenance (WLM) is the weak link in the battle against obesity. Surveys suggest that in the general population, 20% of the initially overweight persons having intentionally lost weight are able to maintain it. Understanding how these “successful losers” manage their weight could help devise efficient WLM interventions. National registries collect the characteristics of weight loss maintainers (WLoMs: previously overweight or obese persons with a weight loss of ≥10% maintained for ≥1 year). The most frequent self-reported strategies are very low energy and fat intake, and high levels of exercise. However, a closer look at the data suggests that the reported intake might be underestimated, since it is similar to the measured resting energy expenditure, and also that physical activity only just reaches normal recommendations. The particularities of WLM thus remain elusive, and while several studies compare WLoMs to weight regainers, none has yet compared WLoMs to persons with a long-term normal, stable weight.
Our HOMAWLO (HOw to MAintain Weight LOss) study and its mixed-method design aimed at gaining a more comprehensive view on WLM by comparing 16 WLoMs and 16 matched Controls with a lifetime normal, stable weight. Their diet, physical activity, eating behaviors, strategies and experiences were assessed by questionnaires and in-depth interviews. The major result was the supplementary burden of WLM, revealed by WLoMs' specific and rigid strategies, their tendency toward more vigorous exercise, their higher scores on eating disorders scales, and a discourse revealing constant worries about eating and weight. Despite all their efforts, their energy and nutrient intake were similar to those of the Controls.
In the meantime, recent publications of large WLM-intervention studies showed disappointing long- term results, with a difference of a few kilos at best between the “intensive” and the “control” groups. This led us to the hypothesis that an excessive drop in resting energy expenditure (REE), mostly described shortly after weight loss, might increase the drive to eat and thus partly explain the burden experienced by our participants. Moreover, coping with food cravings might be more difficult for those with high impulsivity levels, contributing to their higher restraint and disinhibition scores. Only a longitudinal study could verify these hypotheses, and we designed this and assessed its feasibility. We measured dietary intake, body composition, REE, physical activity, impulsivity, weight maintenance strategies and eating disorders among the 50% of initial participants who agreed to follow-up. Our pilot showed good feasibility. There was no evidence for systematically low REE among WLoMs, but our data suggested individual patterns of physiology and behavioral characteristics that should be further explored longitudinally, and taken into account when devising WLM interventions.
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