There may be a link between Vitamin D levels in the body at the start of a low-calorie diet may encourage success.
Subjects in the study had vitamin D levels that many experts are considered insufficient. The authors of the study found that baseline, or pre-diet, vitamin D levels predicted weight loss in a linear relationship. For every increase of 1 ng/mL in level of 25-hydroxycholecalciferol - the precursor form of vitamin D and a commonly used indicator of vitamin D status - subjects ended up losing almost a half pound (0.196 kg) more on their calorie-restricted diet. For each 1-ng/mL increase in the active or "hormonal" form of vitamin D (1,25-dihydroxycholecalciferol), subjects lost nearly one-quarter pound (0.107 kg) more.
Additionally, higher baseline vitamin D levels (both the precursor and active forms) predicted a greater loss of belly fat.