The commission said that people who had a B.M.I. over 25 and too much fat, but who are otherwise healthy, should pretty much be left alone. They should be monitored and counseled not to gain any more weight and possibly to lose some.
Their condition would be called pre-clinical obesity.
Other people with any of the 18 medical conditions caused by obesity — 13 for children and adolescents — require medical treatment to improve their health and prevent serious injuries to organs. The conditions include breathlessness, heart failure, hip or knee pain, metabolic abnormalities and poorly functioning organs.
Their condition would be called clinical obesity.
The group said those with a B.M.I. of 40 or greater have clinical obesity on the basis of their B.M.I. alone — there is no need to assess their body fat.
The commission said it did not know the prevalence of the two types of obesity.
The simplest way for doctors to see whether someone has excess body fat is to wrap a tape measure around a person’s waist, the group said. If a woman’s waist is more than 34.6 inches, she most likely has too much fat. For a man, a waist the threshold would be at least 40 inches.
Other tools for health professionals include waist-to-hip ratios, waist-to-height ratios or DEXA scans, a type of X-ray.
