Bariatric surgery is usually considered when other weight loss efforts have failed. Eligibility criteria were established by the 1991 National Institutes of Health Consensus Development Conference Panel and continue to be the most widely accepted criteria.
BMI is body weight divided by a power of height, usually (height)2, which is said to be independent of stature. Calculations based on values for ideal body weight suggest that BMIs for normal men and women should be in the range of 18.5 to 25 kg/m2. Indeed, this range roughly corresponds to the 10th to 75th percentile values recorded from adult individuals. For infants and children, average BMI values change with age, from 13 kg/m2 at birth, to a peak of 18 at about 1 year, a nadir of 15 at about age 6 years, and then a rise to adult values during adolescence.