Obstructive sleep apnea (OSA) can impars body weight reduction by changes in body composition and energy expenditure. The objective of this study is to evaluate the influence of OSA in energy metabolism and body mass loss in obese subjects. Ninety obese volunteers of both genders, 45 diagnosed with OSA and 45 without OSA, will be submitted to a dietary intervention of one months. Volunteers will be distributed into four groups: obese OSA PTN with moderate protein diet (1.6 g / kg protein / day), obese OSA CHO diet (0.8 g / kg protein / day) with standard composition diet, obese NSAOS PTN diet moderate in protein and CHO NSAOS obese standard diet. All groups will be instructed to perform a restricted energy diet (less 30% of daily energy expenditure). At baseline and one month after the beginning of the program the following evaluations will be conducted: total energy expenditure measured by doubly labeled water method, resting energy expenditure and thermic effect of food by calorimetry, polysomnography analysis, body composition by pletysmography, food consumption by three days of food diary, blood collection for analysis of lipid profile, visceral proteins, hormones related to control of body weight and inflammation. As hypothesis we believe that apneic obese individuals have greater difficult in weight loss and loss more free fat mass than the obese no apneic and that diets with more protein can contribute to greater weight loss, better body composition and energy expenditure in these population.

Inclusion Criteria:

• Body Mass Index between 30 and 40 kg/m2;
• Obstructive sleep apnea mild or severe;
• Sedentary.

Exclusion Criteria:

• Intake of any drug that interfere on metabolism such for thyroid or to lose weight;
• Be engaged in other treatment for sleep apnea or obesity;
• Present another sleep disorder;
• Being shift work;
• Present any kind of kidney disease.