Obesity, or being overweight, is a chronic metabolic disease that occurs due to an imbalance between energy intake and expenditure over an extended period of time and is characterized by excessive accumulation of fat tissue in the body. In clinical practice, it is assessed using the body mass index (BMI), and for an additional evaluation of visceral fat accumulation—which poses a higher risk for the development of cardiovascular and metabolic diseases—waist circumference measurement is used. The modern lifestyle, dominated by sedentary activities and the widespread availability of processed foods high in fats and simple carbohydrates, significantly contributes to the development of obesity. Obesity is a complex condition that can be caused by various factors such as genetics, dietary habits, physical inactivity, environmental, socioeconomic, and psychological factors, as well as certain medical conditions and medications. Obesity is also associated with numerous health problems, such as cardiovascular diseases, diabetes, respiratory issues, musculoskeletal disorders, hormonal problems, and mental health issues. Therefore, the prevention and treatment of the medical complications of obesity are the primary therapeutic goals for young and middle-aged adults, while improving physical function and quality of life is the main therapeutic goal for older adults. Diets are recommended as an intervention to combat obesity, focusing on reducing calorie intake, improving diet quality, and decreasing portion sizes and meal frequency. However, weight loss must be paired with physical activity, which not only contributes to the success of weight loss but also helps reduce pain and increase mobility.