Genetic predisposition to obesity, restrained eating and changes in body weight: a population-based prospective study

There is no consensus on whether cognitive control over food intake (that is, restrained eating) is helpful, merely ineffective or actually harmful in weight management. We examined the interplay between genetic risk of obesity, restrained eating and changes in body weight and size.

Participants were Finnish aged 25-74 years who attended the DIetary, Lifestyle and Genetic determinants of Obesity and Metabolic syndrome study at baseline in 2007 and follow-up in 2014. At baseline (n=5024), height, weight and waist circumference (WC) were measured in a health examination and participants self-reported their weight at age 20 years. At follow-up (n=3735), height, weight and WC were based on measured or self-reported information. We calculated 7-year change in body mass index (BMI) and WC and annual weight change from age 20 years to baseline. Three-Factor Eating Questionnaire-R18 was used to assess restrained eating. Genetic risk of obesity was assessed by calculating a polygenic risk score of 97 known BMI-related loci.

Cross-lagged autoregressive models indicated that baseline restrained eating was unrelated to 7-year change in BMI (β=0.00; 95% confidence interval (CI)=-0.01, 0.02). Instead, higher baseline BMI predicted greater 7-year increases in restrained eating (β=0.08; 95% CI=0.05, 0.11). Similar results were obtained with WC. Polygenic risk score correlated positively with restrained eating and obesity indicators in both study phases, but it did not predict 7-year change in BMI or WC. However, individuals with higher genetic risk of obesity tended to gain more weight from age 20 years to baseline, and this association was more pronounced in unrestrained eaters than in restrained eaters (P=0.038 for interaction).

Our results suggest that restrained eating is a marker for previous weight gain rather than a factor that leads to future weight gain in middle-aged adults. Genetic influences on weight gain from early to middle adulthood may vary according to restrained eating, but this finding needs to be replicated in future studies.