In declaring obesity a disease the NIB signaled a new approach toward obesity. Medical experts no longer regard being obese as a simple failure of will power. Instead, obesity is considered a chronic disease, such as hypertension or diabetes. In 1994 weight loss experts advocated "a conceptual house cleaning" in the way medical doctors and the general public think about weight. The result is new knowledge and a different attitude about the causes and treatments of obesity.

One aspect of obesity that has not changed is its medical consequences. Morbidity occurs more frequently and with greater severity and mortality occurs at an earlier age among obese people compared with those of normal weight. Obesity coexists with or is a precursor of chronic diseases that kill Americans. It is highly correlated with coronary heart disease and stroke. One third of all causes of hypertension are thought to be caused by obesity. It is a major risk factor for some forms of cancer; it predisposes men to cancer of the colon, rectum, and prostate and women to cancer of the ovaries, uterus, and breasts. It increases the body's resistance to insulin and is a leading cause of non insulin dependent diabetes. The risk of diabetes doubles in people who are mildly overweight, is five times higher in the moderately overweight, and is 10 times higher in the severely obese person. Insulin resistance may be the means by which overweight causes cardiovascular diseases. In insulin resistance the body's cells do not respond normally to insulin, and this may contribute to high blood pressure and high triglyceride and cholesterol levels. Obesity contributes to the formation of gallstones; respiratory disorders; degenerative changes in the joints, particularly those of the knees and hips; and low back pain. Complications following surgery occur more often in overweight people compared with those who are not overweight. Wounds don't heal as well or as fast. Infections are more common.

For many people shortness of breath is the first sign of strain placed on the body by excess fat. As fat accumulates, it crowds the space occupied by organs. Some people cannot sit comfortably because of fat accumulation in their abdomens. In a sitting position the individual's lungs have limited space in which to expand.

In addition to the medical hazards, it is not uncommon for obese people to suffer psychological stress, social discrimination, and reduced income. They pay higher premiums for health insurance or are denied coverage, obese children are often ridiculed by their slim peers, and armed forces personnel are forced out of the military if they gain weight beyond an acceptable level.

The link between obesity and chronic diseases is well established, but evidence has emerged indicating that the distribution of fat is equally important. Studies have confirmed that abdominal fat is associated with a higher rate of heart attack and stroke than fat distributed around the hips and thighs .

In summary the health risks and complications associated with excess weight are associated with premature death. When overweight people lose weight, their health usually improves.