The purpose of this study is to evaluate the effects of moderate energy restriction on the body adiposity, severity of OSA, blood pressure, sympathetic activity, oxidative stress, inflammatory biomarkers, metabolic profile and endothelial function in obese patients with OSA.

Introduction: Nutritional intervention for weight loss is one of the treatment options for obstructive sleep apnea (OSA) in patients with excess body adiposity. However, the effects of moderate energy restriction, recommended by current guidelines for the treatment of obesity, on OSA are not yet known. Objective: To evaluate the effects of moderate energy restriction on the body adiposity; severity of OSA; blood pressure; sympathetic activity; oxidative stress; inflammatory biomarkers; metabolic profile and endothelial function in obese patients with OSA. Methods: A 16-week randomized clinical trial, involving 21 subjects with obesity (grade I or II), aged 20-55 years and presenting an apnea/hipopnea index (AHI) > 5 events/h. Participants were randomized into 2 groups: 11 in the energy restriction group (ERG) and 10 in the control group (CG). The ERG was instructed to follow an energy-restricted diet (-800 kcal/day) and the CG was advised not to change their food intake. At the beginning and at the end of the study, participants underwent evaluation of: OSA with the equipment Watch- PAT200® including the determination of the following parameters of OSA severity: AHI, minimum O2 saturation, number of O2 desaturations >4%; body adiposity (weight, %body fat and circumferences of waist, hip and neck); blood pressure (BP); sympathetic nervous system activity (plasma levels of catecholamines); inflammatory biomarkers (c-reactive protein and adiponectin); oxidative stress (malondialdehyde); metabolism of glucose (glucose, insulin and HOMA-IR) and lipids (total cholesterol and fractions and triglycerides); and endothelial function (index of reactive hyperemia evaluated by Endo - PAT 2000® and cellular adhesion molecules). The statistical analysis was performed with the software STATA v. 10. The level of statistical significance was p < 0.05.

Inclusion Criteria:

• age between 20-55 years
• body mass index (BMI) ≥ 30 kg/m2 and < 40 kg/m2

Exclusion Criteria:

• smoking
• Use of dietary supplements
• Use of medications that could interfere in body weight, metabolic profile and blood pressure
• Use of permanent pacemaker; use of α-adrenergic blocking agents
• Recent changes (within previous 6 months) in body weight (> 3 kg), in dietary intake and in intensity or frequency of physical exercise
• Diagnosis of diabetes mellitus, hypertension, dyslipidemia (with drug treatment) and kidney disease
• Clinical history of thyroid dysfunction, angina pectoris, peripheral vascular disease, peripheral neuropathy, heart failure, liver failure, chronic pulmonary disease, gastroesophageal reflux disease, myocardial infarction and stroke; finger deformity that prevents the proper use of the sensors that are necessary to evaluate OSA and endothelial function; and previous bilateral cervical-thoracic sympathectomy
• Pregnant or lactating women were not allowed into the study