These diets have been found to be dangerous and potentially lethal. In fact, the Food and Drug Administration has a ruling that all protein supplements (liquid or powder) used in reducing diets must carry the following label:
Warning—Very low-calorie protein diets (below 800 calories per day) may cause serious illness or death. Do not use for weight reduction without medical supervision. Use with particular care if you are taking medication. Not for use by infants, children, or pregnant or nursing women.
Radical diets such as these can cause disastrous effects on the body, not the least of which are abnormal heart function and severe deficiencies in vital minerals due to extremely rapid weight loss. I couldn’t in good conscience offer supplement suggestions, since I firmly believe that these diets should not be undertaken without strict medical supervision.