The Impact of Very Low-Calorie Diet-Induced Weight Loss on Changes in the Serum Vitamin D Levels, Insulin Resistance, and Inflammatory Biomarkers in Overweight Korean Women

다국어 초록 (Multilingual Abstract)

Obese patients often have low serum levels of 25-OH-vitamin D (25-OH-D), and this may induce insulin resistance and cardiovascular disease. In this study, we investigated whether a reduction in body weight, as achieved within a short period by putting patients on a very low-calorie diet (VLCD), improved the serum 25-OH-D levels. Then we performed a secondary analysis of data collected from a previous study on the impact of a lemon detox program on body fat reduction. We further analyzed any potential correlation between alterations in 25-OH-D levels and changes in biomarkers of insulin resistance and inflammation, which are both related to cardiovascular disease, after weight reduction. A total of 84 pre-menopausal overweight women, who consumed either a VLCD (about 400 kcal/day) or a normal diet for 11 days, were divided into 4 groups by quartiles based on their degree of weight loss. The average serum 25-OH-D level of the entire cohort before the trial was 11.7±3.9 ng/mL, and this level significantly declined after the intervention. However, in the group with the highest weight loss (Q1), which experienced an average body weight reduction of 5.7%, the serum 25-OH-D levels were slightly increased following the weight loss. Further, this increase was significantly greater than that of the other weight loss groups. Weight-loss-induced elevation of serum 25-OH-D levels was significantly associated with a reduction in body weight (p<0.01), body mass index (p<0.05), waist-hip ratio (p<0.05), waist circumference (p<0.01), total body fat mass (p<0.05), serum adiponectin (p<0.01), insulin-like growth factor-1 (p<0.05), and triglycerides (p<0.05). Additionally, as compared to the group with the lowest weight loss, the group with the highest weight loss experienced the largest declines in serum glucose, glycosylated hemoglobin (HbA1c), insulin, and leptin levels and finally insulin resistance. All this data suggests that a loss of 5% or more of body weight can improve the serum 25-OH-D levels and the factors contributing to diabetes and cardiovascular disease.