Effect of very-low-calorie diets with weight loss on obstructive sleep apnea.

To determine the effect of very-low-calorie diets (VLCDs) with weight loss on obstructive sleep apnea (OSA), we studied eight obese subjects with OSA, five males and three females. Subjects consumed a VLCD of 1760 kJ (420 kcal) (67% protein, 4% fat, 29% carbohydrate) or 3350 kJ (800 cal) (20% protein, 30% fat, 50% carbohydrate) with 100% of the recommended daily allowance of vitamins and minerals. Mean (+/- SD) values of weight and respiration before and after weight loss were, for weight, 153 +/- 37 and 132 +/- 29 kg (P less than 0.05); for BMI (kg/m2), 54 +/- 13 and 46 +/- 10 (P less than 0.05); for desaturations/h sleep, 106 +/- 50 and 52 +/- 45 (P less than 0.05); for apneas + hypopneas/h sleep, 90 +/- 32 and 62 +/- 49; for Pco2, 48 +/- 10 and 42 +/- 4 torr (P less than 0.05). Desaturation episodes/h and apnea + hypopneas/h improved in six patients. The most obese subject (female, BMI 81) who lost the most weight (47 kg) did not improve, nor did the subject who lost the least weight, 7 kg. The number of movements + arousals from sleep decreased in all patients (P less than 0.05). We conclude that VLCD with weight loss can produce improvement in OSA; subjects who lose a small amount of weight or subjects who are extraordinarily obese before and after weight loss may not improve.