Dynamic changes in body fat distribution, ectopic fat, and related metabolic improvement in response to weigt loss in obesity.

We investigated the effect of weight loss on fat accumulation in six different tissues and associated metabolic characteristics in individuals with obesity, non-alcoholic fatty liver disease (NAFLD), and the metabolic syndrome (MetS). Baseline assessments were done for individuals with obesity, NAFLD, and MetS (n=33), individuals with obesity (n=28), and lean individuals (n=27), and at 1 and 5 months for the NAFLD-MetS group during personalized weight loss intervention. All measured fat depots were increased in individuals with obesity compared with lean (p<0.001), whereas pancreas (p=0.024) and visceral fat (p=0.007) were elevated in the NAFLD-MetS group compared with the obesity control group. During weight loss, fat content was reduced in all investigated tissues after 1- and 5-months, except for erector spinae muscle fat that was reduced after 5 months. Finally, reductions in alanine aminotransferase, fasting plasma glucose and insulin, waist circumference, and diastolic blood pressure were key for explaining liver fat content after 5 months. Multiple fat depots were increased simultaneously in individuals with obesity, with personalized weight loss intervention leading to reductions in all investigated tissues, especially after 1 month, in individuals with obesity, NAFLD, and MetS. The trial registry number: NCT05699863.