Final answer:
Obesity is medically determined by a BMI greater than 30 kg/m². Morbid obesity is when the BMI is over 40 kg/m². BMI is a general guideline and does not always account for muscle mass in individuals like athletes.
Step-by-step explanation:
The concept of obesity is medically defined by the Body Mass Index (BMI), which is a calculation based on an individual's height and weight. Obesity is diagnosed when an adult's BMI is greater than 30 kg/m². A person is considered morbidly obese when their BMI reaches 40 kg/m² or higher, without necessarily specifying an excess poundage over ideal body weight. It's important to note that BMI is a guideline, and individuals such as athletes may have a higher BMI due to muscle mass rather than fat.
Obesity can be influenced by multiple factors including genetic predispositions, lifestyle choices, and environmental factors. Health risks associated with obesity are significant and include various types of cancers, diabetes, hypertension, and heart diseases amongst others. For children, obesity is typically diagnosed when the BMI is above the 95th percentile for their age group.
The main concern with obesity is not only the weight itself but the associated health risks which can lead to decreased life expectancy and quality of life. Interventions such as dietary changes, increased physical activity, and sometimes medical or surgical treatments can assist in managing obesity.