By submitting your information, you agree to the terms and conditions: Children, teenagers, those soon anticipating a pregnancy, nursing mothers, elderly, frail, and those trying to build a large amount of muscle should not fast. Those who are frail with low muscle mass should not fast. Many people should fast with medical supervision. If there is heart disease, other chronic diseases, metabolic syndrome and diabetes, and people on medication for blood pressure or blood sugar should have medical supervision. People with conditions predisposing to hypoglycemia, as discussed above, should not fast. People with a history of eating disorders should not fast. If your body fat is already very low, fasting may not be well tolerated. Fasting is a hormetic stress that results in healing, but it is a stress. Adrenaline and cortisol levels will be stimulated. People with high stress, high cortisol, severe cravings, and very poor sleep are not ready to fast until these conditions are improved.