Changes in Subcutaneous Fat Cell Volume and Insulin Sensitivity After Weight Loss

Abstract

OBJECTIVELarge subcutaneous fat cells associate with insulin resistance and high risk of developing type 2 diabetes. We investigated if changes in fat cell volume and fat mass correlate with improvements in the metabolic risk profile after bariatric surgery in obese patients. RESEARCH DESIGN AND METHODSFat cell volume and number were measured in abdominal subcutaneous adipose tissue in 62 obese women before and 2 years after Roux-en-Y gastric bypass (RYGB). Regional body fat mass by dual-energy X-ray absorptiometry; insulin sensitivity by hyperinsulinemic-euglycemic clamp; and plasma glucose, insulin, and lipid profile were assessed. RESULTSRYGB decreased body weight by 33%, which was accompanied by decreased adipocyte volume but not number. Fat mass in the measured regions decreased and all metabolic parameters were improved after RYGB (P < 0.0001). Whereas reduced subcutaneous fat cell size correlated strongly with improved insulin sensitivity (P = 0.0057), regional changes in fat mass did not, except for a weak correlation between changes in visceral fat mass and insulin sensitivity and triglycerides. The curve-linear relationship between fat cell size and fat mass was altered after weight loss (P = 0.03). CONCLUSIONSAfter bariatric surgery in obese women, a reduction in subcutaneous fat cell volume associates more strongly with improvement of insulin sensitivity than fat mass reduction per se. An altered relationship between adipocyte size and fat mass may be important for improving insulin sensitivity after weight loss. Fat cell size reduction could constitute a target to improve insulin sensitivity.Obesity is associated with insulin resistance and dyslipidemia and also with a very high risk of developing type 2 diabetes. Interestingly, studies of bariatric surgery (i.e., techniques that reduce or bypass the stomach in order to achieve weight reduction) show, first, that there is no clear quantitative relationship between the weight loss induced by various surgical procedures and the degree of normalization in insulin sensitivity and other metabolic parameters and, second, that metabolism is markedly improved before any significant weight loss is achieved (1,2). In a hallmark study by Klein et al. (3), a large amount of subcutaneous abdominal adipose tissue was removed from obese subjects by liposuction. This was not accompanied by

Lipocalin-type prostaglandin D2 synthase (L-PGDS) modulates beneficial metabolic effects of vertical sleeve gastrectomy

“…Our previous study has also reported an interesting finding regarding adipocyte hypertrophy in the L-PGDS KO mice compared with the C57BL/ 6 mice [8]. Simultaneously, it is also believed that decrease in fat cell volume rather than a decrease in adipose tissue mass after marked weight loss improves greater insulin sensitivity [38]. Therefore, we decided to examine the fat size in mice that underwent VSG compared with the sham surgery.…”

Increased fat cell size: a major phenotype of subcutaneous white adipose tissue in non-obese individuals with type 2 diabetes

“…How could fat cell size play a role in type 2 diabetes? A phenotype characterised by smaller adipocytes, as well as increased adipocyte number in scWAT, correlates with increased insulin sensitivity [27] and a beneficial metabolic profile [28]. Furthermore, genetic predisposition for type 2 diabetes associates with adipocyte hypertrophy in non-obese first-degree relatives [29].…”

Impact of fat mass and distribution on lipid turnover in human adipose tissue

“…In the same subjects, the sWAT mean fat cell size was determined as described in detail previously30. In 148 subjects (only 4 were lean or overweight), we also performed dual X-ray absorptiometry (DEXA) as described31. In brief, body fat composition was assessed using a GE Lunar iDXA and the software enCORE (version 14.10.022)32 provided by the manufacturer (GE Healthcare, Madison, WI, USA).…”