Introduction. Worldwide, obstructive sleep apnea is estimated to affect one in seven individuals. Patients with OSA present chronic low-grade inflammation related to arteriosclerosis. The effect of the Mediterranean diet on metabolic risk indicators is still inconclusive in the OSA population.

Objective: To evaluate the effect of a Mediterranean diet adapted to the Mexican diet, versus standard nutritional treatment, on metabolic risk indicators in patients with obstructive sleep apnea.

Material and methods: Randomized clinical trial in patients with OSA confirmed by polysomnography. Sociodemographic data, pathological and non-pathological history, as well as clinical data will be collected by interview. Patients will be randomly assigned to the group with personalized Mediterranean-type diet adapted to the Mexican diet or standard diet for patients with OSA. At baseline, 6 and 12 months with the patient fasting, glucose levels and lipid profile in venous blood will be measured, as well as carotid artery thickness. Anthropometry and body composition measurements will also be taken, in addition to questionnaires to measure sleep quality, physical exercise and quality of life, as well as to measure dietary adherence with 3-day food records. A descriptive analysis of qualitative variables will be performed with frequencies and percentages; quantitative variables will be presented according to their free or parametric distribution. An X2 will be performed to compare the difference between the proportions of the outcome variables, as well as a Student's t-test or Mann Whitney U test according to their parametric or free distribution. A multivariate analysis will be performed to see the effect of both interventions on the main outcome variables, obesity, dyslipidemia and glycemic control.

Once the inclusion criteria have been confirmed, a detailed explanation of the study will be given, and the responsible investigators will clarify any doubts about the study. The patient will freely agree to participate in the research by signing the informed consent letter.

The following measurements will be taken in all patients:

Sociodemographic and clinical data. A medical interrogation will be made by the research team to collect sociodemographic data, pathological and non-pathological clinical history. The patient will be questioned about his or her age, clinical history with pathological and non-pathological personal history, pharmacological and non-pharmacological treatment.

Blood Pressure Measurement Blood pressure will be measured by the medical team participating in the study, with a calibrated sphygmomanometer, without previous coffee consumption, without having smoked or consumed cola in the last 30 minutes. The patient will be seated in a chair, with his back supported, without crossing his feet.

. Measurement of sleep variables. In the first time consultation of the Sleep Clinic, parameters of AHI and ODI will be taken with the CPAP equipment, which is part of the studies that are routinely performed in patients with obstructive sleep apnea. It lasts 7 to 8 hours.

Polysomnography: We will proceed to the assembly of the channels that make up the polysomnography: electroencephalographic and electro-oculogram derivations, electromyogram of chin and legs, respiratory flow signals thermistor and/or nasal cannula, respiratory effort signals, continuous oxygen monitoring, electrocardiogram, and determination of the patient's body position.

Measurement of biochemical indicators. With the patient fasting for 8 to 10 hours, a blood sample will be taken in venous blood to measure glucose, lipid profile (Cholesterol, Triglycerides, LDH, VLDL). Measurements to be taken at the first consultation, 6 and 12 months.

Anthropometric and body composition measurements The measurement of the anthropometric data will be done by the nutritionists participating in this research, previously standardized.for the measurement of the body composition the InBody equipment will be used, where the percentage of fat, fat mass, lean mass, total liquids will be obtained.

The Epworth Sleepiness Scale, sleep diary, as well as measures and applied sleep changes will be used. The Epworth Sleepiness Scale (ESE) assesses 8 items, each with a 0 to 3 point response, where 0 means no likelihood of nodding off or falling asleep, 1 means slight likelihood of nodding off or falling asleep, 2 moderate likelihood of nodding off or falling asleep, and 3 high likelihood of falling asleep. If the patient scores 1 to 6 it is considered normal sleep, 7 to 8 points average sleepiness, and 9 to 24 points pathological (abnormal) sleepiness.

Apnea-hypopnea index.

This will be obtained through CPAP readings where the level of severity of OSA before and after the intervention will be calculated. It will be classified:

• Mild: apnea-hypopnea index ≥ 5 and < 15 per hour.
• Moderate: apnea-hypopnea index ≥ 15 and ≤ 30 per hour.
• Severe: apnea-hypopnea index > 30 per hour. Measurement of quality of life It will be obtained from the QSQ questionnaire (Quebec Sleep Questionnaire) which has been validated in Hispanic population.

Inclusion Criteria:

• Men and women
• Clinical diagnosis of sleep apnea
• Diagnosis of moderate and severe OSA

Exclusion Criteria:

• Anatomical alterations of the nose, oropharynx or maxilla.
• Chronic kidney disease in substantive treatment of renal function
• Decompensated heart failure
• Cancer
• Depression
• Anxiety
• Neurological disease.
• Treatment with benzodiazepines, antidepressants, anxiolytics and hypnotics.
• Refractory Dyslipidemia
• Familial Dyslipidemia
• Surgeries in less than 6 months

Patients in this group will be given a normocaloric diet with the following energy distribution (Protein: 15-20%, Carbohydrate: 50-55%, Fat: 25-30%, Saturated fat: <7%) according to the guidelines for adult OSA patients. The Mifflin-St. Mifflin equation will be applied to determine the energy needs of each patient. To achieve energy requirements and distribution.

Patients in this group will receive individual nutritional counseling at the beginning of the study on hygienic sleep measures and Mediterranean-type diet adjusted to foods in Mexico that are accessible and inexpensive. Pre-established menus will be calculated with foods that are characteristic of the Mediterranean-type diet, containing fruits, vegetables, whole grains, cereals, white meat content.