Context: The hypothesis of a limited expansion of sc adipose tissue during weight gain provides an attractive explanation for the reorientation of excess lipids toward ectopic sites, contributing to visceral adipose depots and metabolic syndrome.
Objective: Our objective was to define whether the characteristics of sc adipose tissue influence the partition of lipids toward abdominal fat depots during weight gain in healthy men.
Research design and methods: Forty-one healthy nonobese volunteers performed a 56-day overfeeding protocol (+760 kcal/d). Insulin sensitivity was estimated by euglycemic hyperinsulinemic clamp. Changes in abdominal visceral and sc adipose tissue depots were measured by magnetic resonance imaging. The fate of ingested lipids before and after overfeeding was investigated using a [d31]palmitate test meal, and gene expression was measured by real-time PCR in sc fat biopsies.
Results: Overfeeding led to a 2.5-kg body weight increase with large interindividual variations in abdominal sc and visceral adipose tissues. There was no relationship between the relative expansions of these 2 depots, but the increase in visceral depot was positively associated with the magnitude of the postprandial exogenous fatty acid release in the circulation during the test meal. The regulation of lipid storage-related genes (DGAT2, SREBP1c, and CIDEA) was defective in the sc fat of the subjects exhibiting the largest accumulation in visceral depot.
Conclusions: Characteristics of sc adipose tissue appear therefore to contribute to the development of visceral fat depot, supporting the adipose tissue expandability theory and extending it to early stages of weight gain in nonobese subjects.