Free CMWL Berry Bar when you call or reply. Why CMWL? Reason#9: Vitamin D Deficiency. Dr Sack will test your levels with a simple blood test. Results may indicate low levels which may slow down your weight loss because when your body lacks calcium, it may experience an increase in synthase, an enzyme that converts calories into fat. In a study published in the British Journal of Nutrition, obese women who were placed on a 15-week diet and took 1,200 milligrams of calcium a day lost six times more weight than women who followed the diet alone. In addition fueling the body with Vitamin D-rich nutrients, which promotes calcium absorption, drives the body from a fat-storing state into a fat- burning state, and can speed up weight loss.