Effects of a moderate low-carbohydrate diet on preferential abdominal fat loss and cardiovascular risk factors in patients with type 2 diabetes

BACKGROUND: Reports have shown that visceral adipose tissue (VAT) is more closely linked to cardiovascular risk factors (CRFs) than subcutaneous adipose tissue (SAT). We aimed to elucidate preferential abdominal fat loss and the correlations between abdominal fat reductions and changes in CRFs achieved with a moderate low-carbohydrate diet (LCD) in patients with type 2 diabetes (T2DM). PATIENTS AND METHODS: Fifty-two outpatients (28 men and 24 women, mean age ± SD: 60.0 ± 10.5 years) with hemoglobin A(1c) (HbA(lc)) levels ≥ 6.5% were on an LCD for 6 months. Over a 6-month period, we measured their abdominal fat distribution (using CT) and assessed CRFs, including body mass index (BMI), HbA(1c), fasting blood glucose (FBG), serum insulin, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglyceride levels. RESULTS: The patients showed good compliance with the LCD (1812 ± 375 kcal/day, % carbohydrate:fat:protein = 35:40:19 for men; 1706 ± 323 kcal/day, % carbohydrate:fat:protein = 41:36:21 for women). Significant decreases (P = 0.05) in BMI and HbA(1c) levels were observed, along with an increase in HDL-C (P = 0.021) in men and a decrease in LDL-C (P = 0.001) in women. VAT (−21.6 cm(2), P < 0.001 in men; −19.6 cm(2), P < 0.001 in women) and SAT (−13.5 cm(2), P = 0.004 in men; −19.1 cm(2), P = 0.003 in women) significantly decreased. The loss of VAT (%ΔVAT) was greater than that of SAT (%ΔSAT) in women (P = 0.022). A similar but not significant predominance of VAT loss was detected in men (P = 0.111). In women, the %ΔSAT significantly correlated with changes in FBG (ΔFBG) (r = 0.417) and HDL-C (ΔHDL) (r = −0.720), as was %ΔVAT with changes in triglyceride (ΔTG) (r = 0.591). CONCLUSION: Six months of a moderate LCD resulted in preferential VAT loss only in women, with significant correlations between %ΔSAT and both ΔHDL and ΔFBG, as well as between %ΔVAT and ΔTG. Our results suggest that an LCD has the potential to reduce abdominal fat in patients with T2DM and deterioration of serum lipid profiles.