Is dieting a risk for higher weight gain in normal-weight individual? A systematic review and meta-analysis.

While there is an increasing prevalence of dieting in the overall population, weight loss practices could be a risk factor for weight gain in normal-weight individuals. The aim of the present work was to systematically review all the studies implicating diet restriction and body weight evolution in normal-weight people. The literature search was registered in PROSPERO (CRD42021281442) and was performed in three databases from April 2021 to June 2022 for articles involving healthy normal-weight adults. From a total of 1487 records initially identified, 18 were selected in the systematic review. Of the 8 dieting interventional studies, only one found a higher body weight after weight recovery, but 75% of them highlighted metabolic adaptations in response to weight loss favoring weight regain and persisting during/after body weight recovery. Eight of the 10 observational studies showed a relationship between dieting and major later weight gain while the meta-analysis of observational studies results indicated that 'dieters' have a higher body weight than 'non-dieters'. However, considering the high methodological heterogeneity and the publication bias of the studies, this result should be taken with caution. Moreover, the term 'diet' was poorly described and we observed a large heterogeneity of the methods used to assess dieting status. Present results suggest that dieting could be a major risk factor for weight gain in the long term in normal-weight individuals. There is however a real need for prospective randomized controlled studies specifically assessing the relationship between weight loss induced by diet and subsequent weight in this population.