A high protein, low calorie liquid diet in the treatment of very obese adolescents: long-term effect on lean body mass.

The use of Optifast-70, a high protein liquid diet, when used in the range of 500 to 700 cal over 5 months in very obese adolescents, was associated with weight loss of 20 to 25% of initial weight of which 70 to 75% of the loss was due to fat. No significant side effects were noted. Twenty-four hour electrocardiographic monitoring showed no significant changes, and linear growth continued. Lean body mass loss was 36% of the weight lost during the first 5 wks, but was only 10% of the weight lost during the next few months. Two adolescent males had negative phosphorus and nitrogen balances over the first 4 wk, implying that males may have slightly higher phosphorus, nitrogen, and calorie requirements.