Is there a threshold of visceral fat loss that improves the metabolic profile in obese postmenopausal women?

Abstract

It is presently unclear how much visceral adipose tissue (VAT) loss is needed to induce favorable metabolic changes. Cross-sectional studies have proposed that a threshold level of VAT exceeding 110 cm(2) in women induces deleterious changes in the metabolic profile. It is presently unclear, however, if significant decreases in VAT below this given threshold significantly improve the metabolic profile more as compared to decreases that remain below 110 cm(2). To examine whether achieving versus not achieving the proposed VAT threshold impacts differently on the metabolic profile in postmenopausal women, we examined the effects of a VAT loss below the 110-cm(2) threshold versus those individuals who remained higher than 110 cm(2) after a weight loss program. Twenty-five sedentary obese (baseline % body fat, 47.7% +/- 4.1%; [mean +/- SD]) postmenopausal women aged between 51 and 71 years (59.7 +/- 5.6 years) and displaying high baseline levels of VAT accumulation (223 +/- 45 cm(2)) were submitted to a 1-year weight loss program with weight stabilization periods before and after weight reduction. Based on their loss of VAT after weight loss, subjects were characterized as "attainers" (post VAT levels < 110 cm(2); average, 96 +/- 10 cm(2); n = 10) or "non-attainers" (post VAT levels > 110 cm(2); average, 171 +/- 34 cm(2); n = 15). We compared changes in (1) plasma lipid-lipoprotein levels, (2) insulin sensitivity (euglycemic/hyperinsulinemic clamp), and (3) supine resting blood pressure between groups who achieved these 2 distinct levels of VAT. Attainers showed a 2-fold greater loss of VAT compared to non-attainers (-51.5% v -27.5%, P <.001). Attainers also showed a greater loss of body weight (-19.0% v -12.5%, P <.01) and fat mass (-34.8% v -18.4%, P <.001) after the program compared to non-attainers. Despite significant differences in the loss of total fat and VAT after the weight loss program, attainers and non-attainers showed comparable improvements for plasma high-density lipoprotein-cholesterol (HDL-chol) levels (+62.5% v +50.0%, P = not significant [NS]), cholesterol/HDL-chol ratio (-45.5% v -36.5%, P = NS), insulin sensitivity (+34.1% v +23.2%, P = NS), and resting systolic (-6.9% v -5.1%, P = NS) and diastolic (-11.3% v -11.1%, P = NS) blood pressure. These results do not favor the idea that attaining levels of VAT below a threshold of 110 cm(2) is necessary to favorably improve the metabolic profile in obese postmenopausal women. Achieving or not the proposed threshold of VAT, independently of baseline values, appears to yield similar metabolic improvements in obese postmenopausal women. More moderate losses of VAT appear to yield similar metabolic improvements as large losses.