Macronutrient Intake–Associated FGF21 Genotype Modifies Effects of Weight-Loss Diets on 2-Year Changes of Central Adiposity and Body Composition: The POUNDS Lost Trial

OBJECTIVE Fibroblast growth factor 21 (FGF21) is involved in the regulation of energy balance and adipose metabolism. Our previous genome-wide association study identified genetic variants in the FGF21 region associated with macronutrient intake preference. We investigated whether the FGF21 genotype modified effects of weight-loss diets varying in macronutrient intake on changes in adiposity in a 2-year randomized diet intervention trial. RESEARCH DESIGN AND METHODS We genotyped FGF21 rs838147 in 715 overweight or obese individuals who were assigned to one of four diets varying in macronutrient contents. A DEXA scan was performed to evaluate body composition. RESULTS We observed a significant interaction between the FGF21 genotype and carbohydrate/fat intake on 2-year changes in waist circumference (WC), percentage of total fat mass, and percentage of trunk fat (P = 0.049, P = 0.001, and P = 0.003 for interaction, respectively). In response to the low-carbohydrate/high-fat diet, carrying the carbohydrate intake-decreasing C allele of rs838147 was marginally associated with less reduction in WC (P = 0.08) and significantly associated with less reduction of total fat mass (P = 0.01) and trunk fat (P = 0.02). Opposite genetic associations with these outcomes were observed among the high-carbohydrate/low-fat diet group; carrying the C allele was associated with a greater reduction of WC, total body fat mass, and trunk fat. CONCLUSIONS Our data suggest that FGF21 genotypes may interact with dietary carbohydrate/fat intake on changes in central adiposity and body fat composition. A low-calorie, high-carbohydrate/low-fat diet was beneficial for overweight or obese individuals carrying the carbohydrate intake-decreasing allele of the FGF21 variant to improve body composition and abdominal obesity.