Final answer:
Admission to a rehabilitation facility is generally based on meeting specific diagnostic criteria, which in the case of obesity, involves having a BMI of 40 or more, known as morbid obesity.
Step-by-step explanation:
The rule of thumb to be admitted to a rehabilitation facility is not based on a BMI below 25, a regular exercise routine, or necessarily a doctor's prescription alone, but rather on meeting specific diagnostic criteria. For example, someone may need rehabilitation if they are dealing with morbid obesity, which is diagnosed when a person has a BMI ≥ 35 kg/m² and obesity-related health problems, or when a person has a BMI ≥ 40 kg/m². The body mass index (BMI) is a measure used to determine categories such as underweight, normal weight, overweight, and obese. Thus, a patient with a BMI over 40 is considered to have morbid obesity. The treatment for obesity often involves lifestyle changes, such as diet and physical activity, but in extreme cases, can include medications or bariatric surgery.