Vitamin D supplementation helps weight loss in obese and overweight patients with vitamin D deficiency, according to research findings presented at the European Congress on Obesity, held from May 6 to 9 in Prague.

Previous studies have shown that vitamin D deficiency is associated with both developing obesity and the risk of obesity related complications, but studies on the effects of vitamin D supplementation have been inconclusive.

To establish whether restoration of optimal vitamin D status would promote weight loss and improve the metabolic profile of obese or overweight patients with a vitamin D deficiency, Luisella Vigna, MD, of the University of Milan, Italy, and colleagues analyzed data from 400 obese or overweight patients from 2011 to 2013.

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All participants received a balanced moderately low calorie diet and were assigned to one of three groups: 1) no supplementation 2) vitamin D supplementation using cholecalciferol 25,000 international units (UI) per month 3) vitamin D supplementation using cholecalciferol 100,000 UI per month.

At the start of the study and 6 months later, the investigators measured body parameters, including body mass index (BMI) and waist circumference; body composition; plasma levels of vitamin D, fasting glucose, fasting insulin and HbA1c levels.

Six-month supple­mentation with 25.000 and 100.000 UI increased serum vitamin D levels, but only 100.000 allowed achievement of optimal vitamin D status. A significantly greater weight decrease was observed in the 25.000 and 100.000 UI groups (–3.8 kg and –5.4 kg) compared to no supplementation (-1.2 kg). Waist circumference reduction was more substantial in the vita­min D group (25.000: –4.00 cm; 100.000: –5.48 cm; no supplementation: –3.21 cm). Adjustment for age, sex, and BMI did not affect statis­tical significance.

Improved blood sugar control was noted in patients supplemented with 100.000 UI, but this finding lost significance after adjustment for weight decrease, meaning this was probably caused by the weight loss rather than the supplementation.

“The present data indicate that in obese and overweight people with vitamin D deficiency, vitamin D supplementa­tion aids weight loss and enhances the beneficial ef­fects of a reduced-calorie diet,” concluded the investigators.

“All people affected by obesity should have their levels of vitamin D tested to see if they are deficient, and if so, begin taking supplements.”


  1. Vigna L et al. “Vitamin d supplementation promotes weight loss and waist circumference reduction in overweight/obese adults with hypovitaminosis d.” Presented at: European Congress on Obesity. May 6-9; Prague.