Obesity is defined as a condition in which a person has excessive body fat, with a Body Mass Index (BMI) of 30 or higher. BMI is a measurement that compares a person’s weight to their height. Excessive accumulation of fatty tissue may lead to serious health consequences, such as diabetes, high blood pressure, and elevated blood lipid levels. Obesity is one of the most common medical conditions in Western societies today and one of the most challenging conditions to manage and treat. Although progress in obesity treatment has been relatively limited, apart from interventions based on lifestyle modification, considerable information has been gathered regarding the medical consequences associated with obesity. First: Symptoms and Diagnosis of Obesity Obesity is diagnosed when the Body Mass Index (BMI) is 30 or higher. BMI is calculated by dividing a person’s weight in kilograms by the square of their height in meters. The classification is as follows: • Underweight: Below 18.5. • Normal weight: 18.5–24.9. • Overweight: 25–29.9. • Obesity: 30 or higher. For most individuals, BMI provides a reasonable estimate of body fat. However, it does not directly measure body fat. Therefore, some individuals, such as athletes with high muscle mass, may have a BMI within the obesity range despite not having excessive body fat. Second: Causes of Obesity 1. Physical Inactivity Physically inactive individuals burn fewer calories than those who are physically active. Health surveys have demonstrated an association between physical inactivity and weight gain in both men and women. 2. Overeating Overeating leads to weight gain, particularly when the diet contains high amounts of fat. Foods rich in fats or sugars, such as fast food, fried foods, and sweets, have a high energy density, meaning they contain large amounts of calories in relatively small portions. 3. Genetics A person is more likely to develop obesity if one or both parents have obesity. Genetic factors also influence hormones involved in fat regulation. One example is leptin deficiency. Leptin is a hormone produced by fat cells and the placenta. It helps regulate body weight by sending signals to the brain to reduce food intake when the body’s fat stores become sufficiently high. If the body cannot produce enough leptin for any reason, or if the hormone cannot effectively signal the brain to reduce food intake, this regulatory mechanism becomes impaired, potentially contributing to obesity. 4. A Diet Rich in Simple Carbohydrates The role of carbohydrates in weight gain remains a subject of research. Carbohydrates increase blood glucose levels, which stimulate the pancreas to release insulin. Insulin helps regulate energy storage and supports the growth of adipose tissue. Some scientists believe that simple carbohydrates, such as sugars, fructose, sweets, and soft drinks, may contribute to weight gain because they are absorbed into the bloodstream more rapidly than complex carbohydrates, such as pasta, brown rice, grains, and vegetables. 5. Eating Frequency The relationship between eating frequency and body weight remains somewhat controversial. Some reports suggest that people with overweight may eat less frequently than individuals with normal body weight. Scientists have observed that individuals who consume four or five small meals per day may have lower cholesterol levels and lower, more stable blood glucose levels compared with those who eat less frequently, such as two or three large meals per day. One possible explanation is that eating small, frequent meals may help maintain more stable insulin levels, whereas large meals may cause significant increases in insulin levels after eating. 6. Medications Medications associated with weight gain include certain antidepressants, anticonvulsants, some diabetes medications, certain hormonal contraceptives, and most corticosteroids, such as prednisone.Some medications used to treat high blood pressure and certain antihistamines may also cause weight gain. The mechanisms responsible for medication-related weight gain vary depending on the drug. Therefore, individuals who are concerned about this side effect should discuss their medications with their healthcare provider rather than stopping them independently, as discontinuation may lead to serious health consequences. 7. Psychological Factors Emotions can influence eating habits in some individuals. Many people tend to overeat in response to different emotional states, such as boredom, sadness, stress, or anger. Although most individuals with overweight do not experience more psychological disorders than those with normal body weight, approximately 30% of individuals seeking treatment for severe weight-related problems experience difficulties associated with binge eating. 8. Diseases Certain medical and hormonal disorders may contribute to obesity or weight gain. These include hypothyroidism, insulin resistance, polycystic ovary syndrome (PCOS), and Cushing’s syndrome. 9. Social Factors There is an association between social difficulties and an increased risk of obesity. Limited financial resources to purchase healthy foods or a lack of safe places for walking and exercising may increase the risk of developing obesity. Al Mustaqbal University The First University in Iraq