Obesity can be defined as' a disease that occurs as a result of the energy (calorie) taken with food being more than the energy consumed and the excess energy being stored as fat in the body, negatively affecting the quality and duration of life. BMI is calculated by dividing the weight (kg) by the square of the height (m2) (1,2). According to the World Health Organization (WHO) classification, BMI between 25-29.9 kg / m2 is overweight, 30-34.9 kg / m2 is light, 35-39.9 kg / m2 is medium, 40 kg / m2 and above is considered as severe obesity. Obesity has important effects on respiratory function. These mechanical and biochemical effects are not easily measured by pulmonary function test and BMI measurement.Changes caused by mediators produced by adipose tissue likely cause changes in lung function, but this effect is not fully understood at the moment. The aim of our study is to make these effects more understandable and to compare them with different obesity classes and people with normal weight who are considered healthy.

Hypothesis 0: The effects of obesity on respiratory functions and multidimensional health-related parameters do not show a statistically significant difference compared to individuals with different levels of the disease and normal weight individuals classified as healthy.

Hypothesis 1: The effects of obesity on respiratory functions and multidimensional health-related parameters show a statistically significant difference compared to people with different levels of the disease and normal weight individuals classified as healthy.

The study will be carried out by face-to-face evaluations in a clinical setting with obese patients between the ages of 18-65 who have applied to the clinic with a diagnosis of obesity and agree to participate in the study, and healthy volunteers who are considered to be healthy without a diagnosis of obesity. Looking at the evaluations to be made; Measurement of respiratory function parameters, measurement of respiratory muscle strength, anthropometric measurements, evaluation of body composition, quality of life, upper extremity muscle strength and grip strength, lower extremity muscle strength, fatigue evaluation, vital signs, evaluation of exercise perception, presence of dyspnea and its level will be evaluated. A detailed description of these evaluations and the parameters to be used will be explained in detail in the next step.

Obesity can be defined as' a disease that occurs as a result of the energy (calorie) taken with food being more than the energy consumed and the excess energy being stored as fat in the body, negatively affecting the quality and duration of life. A body mass index (BMI) of 30 or above in adults is classified as obese. BMI is calculated by dividing the weight (kg) by the square of the height (m2). According to the World Health Organization (WHO) classification, BMI between 25-29. 9 kg / m2 is overweight, 30-34. 9 kg / m2 is light, 35-39. 9 kg / m2 is medium, 40 kg / m2 and above is considered as severe obesity. As the increases in BMI are related to the number of comorbidities, weight loss also affects many risk factors. It has been shown that voluntary weight loss in obese individuals over short periods (weeks or months) reduces risk factors and improves disease symptoms associated with obesity, including heart disease, Type II Diabetes mellitus, and osteoarthritis. Obesity; It is an important risk factor and disease factor for asthma, obstructive sleep apnea syndrome, obesity hypoventilation syndrome (OHS) and pulmonary hypertension diseases. The overall effect of obesity on lung function is multifactorial and is related to the mechanical and inflammatory aspects of obesity. Obesity has important effects on respiratory function. These mechanical and biochemical effects are not easily measured by pulmonary function test and BMI measurement. Changes caused by mediators produced by adipose tissue likely cause changes in lung function, but this effect is not fully understood at the moment.As a result of the literature review the investigators conducted, it was observed that the studies conducted in order to make more understandable the physiological and mechanical effects of obesity on different systems in the body, especially the respiratory system, were limited and inadequate in terms of numerical and targeted purposes. It was observed that lower extremity muscle strength, fatigue, sleep quality parameters were not included, and their relations with respiratory system functions and measurements were not measured. The aim of our study is to make these effects more understandable and to compare them with different obesity classes and people with normal weight who are considered healthy. Individuals who volunteered to participate in the study, who met the inclusion criteria and volunteered to participate will be evaluated by dividing them into five different groups according to the BMI parameter, in accordance with the intervals determined by WHO, and the data obtained will be compared between the groups.

Outcome Measures:

• Measurement of Pulmonary Function Parameters: The respiratory function parameters of the participants will be measured with a respiratory function test using a spirometer. With these tests, the static and dynamic lung volumes and functional status of the person will be determined.
• Measurement of Respiratory Muscle Strength:

It consists of respiratory muscles, diaphragm, intercostal (internal and external), scalene, sternocleidomastoid, triangularis sterni, abdominal, shoulder and neck muscles. Respiratory muscle strength can be measured in many different ways. Among the pulmonary function tests, maximum inspiratory and expiratory pressures are the measurements that are frequently used to evaluate the strength of the respiratory muscles. -Measurement of Respiratory Muscle Strength:It consists of respiratory muscles, diaphragm, intercostal (internal and external), scalene, sternocleidomastoid, triangularis sterni, abdominal, shoulder and neck muscles. Respiratory muscle strength can be measured in many different ways. Among the pulmonary function tests, maximum inspiratory and expiratory pressures are the measurements that are frequently used to evaluate the strength of the respiratory muscles. These measurements are directly related to respiratory muscle strength and help to determine the rehabilitation and exercise program by providing information about the patient's condition.

-Anthropometric Measurements: Participants' waist circumference, hip circumference, neck circumference will be measured, and their ratios (waist / height ratio, waist / hip ratio) will be calculated. Body mass index (BMI), waist circumference, and waist-to-hip ratio (B / C) is the diagnostic methods commonly used to detect adiposity. Waist circumference and waist-hip ratio have been found to be useful measurements for measuring visceral fat accumulation. Measurement of neck circumference is used as an anthropometric marker to identify patients at risk for sleep apnea syndrome. At the same time, neck circumference is thought to be associated with other metabolic diseases. In addition to these measurements, the measurement called 'New BMI' used in the literature will also be made. In this measurement, BMI is calculated with the formula 1.3 × (kg / m2).

In order to calculate the body fat ratio, it is aimed to estimate the amount of body fat with the measurement of Clinica Universidad de Navarra-Body Adiposity Estimator (CUN-BAE) in addition to the bioelectric impedance method.

BMI measurement is insufficient to determine body fat and muscle ratio. Since it is difficult to determine the location of the fat tissue in the body, it will be evaluated with the '' Body Shape Index ''.

-Assessment of Body Composition: Body composition will be measured using the method called bioelectrical impedance analysis (BIA). This measurement is based on the principles of electrical conductivity of body tissues. It is a fast, practical and relatively inexpensive method compared to other similar devices and applications used to examine the body composition of individuals. This method shows the percentage and mass of body fat, lean body weight and the amount of water in the body and their distribution percentage. The person climbs on the device and places his or her hands in the designated places. Electric current travels through the body and provides information about parameters determined by certain algorithms and calculations.

-Quality of Life: Quality of life is accepted as a multidimensional structure with many different contents. Considering the decrease in physical capacity, pain, deterioration in interpersonal relationships, decreased self-esteem, loss of self-esteem, depression, social stigma, difficulty in finding a job, rejection by the school and business environment, it is understood how low the health-related quality of life of obese individuals is. In measuring the quality of life; Nottingham Health Profile questionnaire will be used. Nottingham Health Profile is a questionnaire consisting of 7 subtitles and 45 questions, including physical, social and psychological evaluations.

-Upper Extremity Muscle Strength and Gripping Strength: It is an important parameter related to muscle strength, functional capacity, cardiovascular disease risk factors and mortality. Upper extremity muscle strength and grip strength will be measured by hand dynamometer and weight lifting tests (arm curls test).

-Lower Extremity Muscle Strength: Abnormalities that usually occur in lower extremity muscles affect patients' physical performance and daily living activities, reduce exercise tolerance and impair health-related quality of life. 30-second sit-and-go test will be used to measure lower extremity muscle strength. The score is determined by the number of times the participant sits and stands up for 30 seconds from the moment the participant is commanded to place his hands on the crossed, shoulders in the chair he is sitting with his back supported and to start in the position where his feet are in full contact with the floor.

• Fatigue Assessment:

Fatigue is a common complaint in overweight and obese people. It has been stated that this is caused by increased body mass, decreased physical activity level and sleep disorders. In the assessment of fatigue, the Fatigue Severity Scale (39) will be used. The fatigue severity scale consists of 9 questions that question social relationship, physical performance and symptomatically the severity of fatigue. The total score is created according to the answers given to the questions.

-Vital Sign: Type 2 diabetes mellitus (T2DM), hypertension (HT), dyslipidemia (DLP), obstructive sleep apnea syndrome (OSAS) comorbidities have been associated with morbid obesity in obese individuals. Blood pressure, heart rate, oxygen saturation will be evaluated in order to observe the negative effects of these comorbidities.

-Evaluation of Exercise Perception: Aerobic exercise capacity is an essential component of physical fitness. Perceived benefits and perceived barriers to participating in physical activity will be assessed by Exercise Benefits / Barriers Scale (EBBS). It is a questionnaire consisting of 43 questions used to evaluate people's perception of exercise. Evaluates the ideas of being useful and preventive that exercise creates on people. The test score is determined by the score collected according to the answers given to the questions.

-Assessment of the Presence and Level of Dyspnea: According to the American Thoracic Society (ATS) report, the definition of dyspnea was defined as "unpleasant or uncomfortable breathing sensation and personal respiratory disturbance caused by various intensity senses" and it was stated to be a subjective feeling. "Modified Medical Research Council Scale (MMRC)" will be used to evaluate the presence of dyspnea. The MMRC is a five-item scale created on the basis of various activities that cause shortness of breath. The presence and effect of dyspnea occur according to the substance chosen by the person.

-Statistical method (s) to use: '' Hatem AM, Ismail MS, El-Hinnawy YH. 'Effect of different classes of obesity on the pulmonary functions among adult Egyptians: a cross-sectional study', Egypt J Bronchol 2019; 13: 510-5 '', the total number of samples determined for 5 groups in the sample size study, based on the FVC value and standard deviations in table 2, was calculated as 80 on the condition that it was 16 per group. Sample size calculation was made using the NCSS / PASS program. In the calculation, it was determined that the difference between the averages of the 5 groups should be 80% power and 95% confidence level to be significant. The statistical test method to be applied ANOVA will be used in conditions of normal distribution between groups, and Kruskal-Wallis test method will be used if the condition of normal distribution between groups cannot be achieved.

Inclusion Criteria:

• Being in the age range of 18-65,
• body mass index ≥18.5 according to the World Health Organization (WHO) classification,
• Volunteering to participate in the study,

Exclusion Criteria:

• Accompanying neurological or orthopedic effects that will prevent participation in the study,
• Pregnancy status,
• Presence of a pacemaker,
• Having had Covid-19 disease ,
• Having had any thoracic or abdominal surgery or injury,
• For evaluation and control purposes Being unable to understand and apply the tests to be applied mentally and physically successfully,

According to the WHO classification, the five groups to be formed will be group I normal weight (healthy), group II overweight, group III, class 1 obese, group IV, class 2 obese, group V, class 3 (morbid) obese.