Obesity can be thought of as an imbalance of energy metabolism in which excess energy is stored in fat cells. Along with the imbalance in energy metabolism, there are other metabolic abnormalities that are associated with obesity. Obesity increases the risk of type 2 diabetes and the metabolic syndrome. In addition, obesity can be associated with disturbances of cholesterol and triglyceride metabolism. Several vitamin and mineral deficiencies can occur in the setting of obesity. It has been proposes that a deficiency of vitamin D may be a cause of some forms of obesity, and it has been found that vitamin D levels are lower in individuals that are overweight and obese.
Researchers, led by Dr. Farhad Hosseinpanah from Shahid Beheshti University of Medical Sciences in Iran, have found that vitamin D supplementation in overweight and obese women causes reductions in body fat mass. The results of their study were published online in the Nutrition Journal. The researchers conducted a double blind randomized clinical trial in 77 overweight and obese women (average BMI 29) to determine the effect of vitamin D supplementation on weight and fat composition. The experimental group received 1000 IU of vitamin D for a 12 week period. The researchers found that in the vitamin D group, serum levels of vitamin D rose significantly and a corresponding decrease of parathyroid hormone was observed. Vitamin D supplementation also caused a statistically significant decrease in body fat mass compared to the placebo group. Body weight and waist circumference did not change significantly between the vitamin D group and the placebo group.
The authors wrote, “The present study shows that a 12 week supplementation with 25 μg vitamin D3 in overweight and obese women with mean serum 25(OH)D concentrations of 41.8±31.4 nmol/L decreases body fat mass, but does not affect body weight and waist circumference”.
The authors also wrote, “Our study is one of the few clinical trials which have investigated the effect of vitamin D3 supplementation in overweight or obese women with low 25(OH)D concentrations on body compositions. The 12 week vitamin D3 supplementation did not significantly affect body weight, waist or hip circumference. However, a modest fat mass reduction of 7% was associated with a significant increase of 25OHD levels by 103% and a significant decrease of PTH levels by 14%”.
Vitamin D deficiency is common in individuals who are overweight or obese. Vitamin D is a fat soluble vitamin and the increased adipose tissue may serve as a reservoir for the vitamin in these individuals. As a result, those who are overweight and obese may require more vitamin D that leaner individuals. In this study, it was shown that vitamin D supplementation decreases fat mass, but not overall weight in overweight and obese women. The overall result was that vitamin D supplements decreased fat by an average of 2.7 kilograms while increasing muscle by an average of 1.8 kilograms. Future studies need to determine whether vitamin D deficiency is causative in obesity and elucidate its role in body fat composition.
Amin Salehpour et al. “A 12-week double-blind randomized clinical trial of vitamin D3 supplementation on body fat mass in healthy overweight and obese women” Nutrition Journal 11:78 published online September 22, 2012 doi:10.1186/1475-2891-11-78