The Obesity Code: Unlocking the Secrets of Weight Loss (Why Intermittent Fasting Is the Key to Controlling Your Weight)

by Jason Fung

Many people worry that fasting may cause malnutrition, but this concern is misplaced. The body’s fat stores are, for most of us, quite ample for our bodies’ needs. Even studies of prolonged fasting have found no evidence of malnutrition or micronutrient deficiency. Potassium levels may decrease slightly, but even two months of continuous fasting did not decrease levels below normal, even without the use of supplements.11 Note that this duration of fasting is far longer than is generally recommended without medical supervision. Magnesium, calcium and phosphorus levels during fasting are stable12—presumably, because of the large stores of these minerals in the bones. Ninety-nine percent of the body’s calcium and phosphorus is stored in the bones. A multivitamin supplement will provide the recommended daily allowance of micronutrients. In one case, a therapeutic fast of 382 days was maintained with only a multivitamin, with no harmful effect on the subject’s health. Actually, this man maintained that he felt terrific during the entire period.13 There were no episodes of hypoglycemia, as blood sugars were maintained within the normal range. The only concern may be a slight elevation in uric acid, which has been described in fasting.14