Recently, in a double-blind, randomized clinical trial (RCT) [41], albeit on a modest sample (44 patients enrolled for 3 months), insulin resistance, glucose homeostasis, and metalloproteases (MMP-9) were evaluated in obese subjects (BMI: 30–40 kg/m2) with a deficiency of vitamin D (25 (OH)-D: ≤50 nmol/L; ≤20 ng/mL) in which, with double-blind randomization, a high dose of vitamin D3 (50,000 U/week) was administered for 3 months together with a weight loss diet. Here, MMP9 is linked to Insulin resistance.