Supplementation With Vitamin D Improves Leptin Resistance

Effect of Vitamin D Supplementation on Leptin Resistance, Hunger, Body Weight and Resting Energy Expenditure in Obese Women.

Participants will be randomly assigned in one of two groups. Group A: oral supplementation with 4,000 IU of vitamin D (cholecalciferol). Group B: oral supplementation with 400 IU of vitamin D (cholecalciferol). Both treatments will be consumed daily for 6 months. Outcomes will be evaluated at baseline, three and six months. Variables related to leptin resistance will be evaluated. The main hypothesis is that vitamin D will diminish leptin resistance in overweight and obese women. If the hypothesis is confirmed, women will show a reduction in the Resting energy expenditure: serum Leptin ratio (REE: Leptin ratio), as well as a reduction of hunger, body weight, body and abdominal fat and an increase in resting energy expenditure.

Study subjects will get dietary advice and physical activity counseling. At the end of the study, participants with suboptimal vitamin D levels (<80 nmol/L 25-OH-D) will receive treatment to normalize their vitamin D status. Variables related to leptin resistance like resting metabolic expenditure, hunger, body weight and human body fat will be assessed. Outcomes will include, glucose, insulin, C-reactive protein, inflammatory interleukins (IL-6 & TNF-α) and non-inflammatory interleukins (IL-10 & TGF-β-1).

Control: (n=50) Each subject will be evaluated after supplementation during six months with Vitamin D (Cholecalciferol: 400 IU/day)

Experimental: (n=50) Each subject will be evaluated after supplementation during six months with Vitamin D

Evaluation of leptin resistance: (resting energy expenditure: leptin ratio) before and after (3 and 6 months) supplementation with vitamin D3 (cholecalciferol) 4,000 or 400 IU/day.

Effect of vitamin D supplementation (25-OH-D): hunger, body weight, energy intake, resting energy expenditure, and body fat, improvement on low intensity chronic inflammation, SOCS-3 expression and JAK2/STAT3 signal.

Inclusion Criteria: BMI: 25-29.9 Serum vitamin D levels: 20-80 nmol/L (25-OH-D) Exclusion Criteria: Liver disease Kidney disease Diabetes mellitus Malignity Any kind of hormonal disorder Medication that modify hunger/satiety answer and those medications that alter -the glucose/insulin metabolism Subjects with diet treatment to lose weight