Caloric Restriction and Diet-Induced Weight Loss Do Not Induce Browning of Human Subcutaneous White Adipose Tissue in Women and Men with Obesity.

Caloric restriction (CR) is standard lifestyle therapy in obesity management. CR-induced weight loss improves the metabolic profile of individuals with obesity. In mice, occurrence of beige fat cells in white fat depots favors a metabolically healthy phenotype, and CR promotes browning of white adipose tissue (WAT). Here, human subcutaneous abdominal WAT samples were analyzed in 289 individuals with obesity following a two-phase dietary intervention consisting of an 8 week very low calorie diet and a 6-month weight-maintenance phase. Before the intervention, we show sex differences and seasonal variation, with higher expression of brown and beige markers in women with obesity and during winter, respectively. The very low calorie diet resulted in decreased browning of subcutaneous abdominal WAT. During the whole dietary intervention, evolution of body fat and insulin resistance was independent of changes in brown and beige fat markers. These data suggest that diet-induced effects on body fat and insulin resistance are independent of subcutaneous abdominal WAT browning in people with obesity.