The new drug increased growth hormone levels to those of healthy young adults. Moreover, the pituitary gland released growth hormone in the normal pulsatile pattern throughout the day. Compared with placebo, MK-677 had several effects. Body weight increased, as did fat-free mass (most of which is muscle), water inside cells, and fat on the arms and legs. Also, the body's sensitivity to insulin decreased, and blood sugar increased. Neither MK-677 nor placebo had an effect on thigh muscle area, muscle strength, or function.