Final answer:
Obesity is defined as having a BMI above 30 kg/m² and is linked to numerous health risks. Factors contributing to obesity include a a poor diet, inactivity, and genetic predispositions. While BMI is useful for diagnosing obesity, it has limitations and does not account for muscle mass.
Step-by-step explanation:
Obesity is a disease characterized by an excess accumulation of body fat to the extent that it may negatively impact health. It is commonly diagnosed using the body mass index (BMI), a calculation of body fat based on the ratio of a person's weight to their height squared. A BMI above 30 kg/m² is considered obese. Obesity can stem from various factors, including overeating, poor diet, lack of physical activity, insufficient sleep, genetics, and other health conditions or medication use.
Severe or long-term obesity may lead to numerous health complications, such as coronary heart disease, type 2 diabetes, certain forms of cancer, hypertension, dyslipidemia, stroke, and more. It's also associated with lower life expectancies and increased healthcare costs. However, it's crucial to note that while BMI is a useful tool for population studies, it may not be as accurate for individuals due to its inability to differentiate between muscle and fat mass. Implementing lifestyle changes and losing weight can significantly reduce and sometimes reverse the complications associated with obesity. As such, it's seen as a preventable condition that can be managed with the right interventions.