While “eating too much” may be a substantial cause for obesity, the disease is much more complex than that. Certainly when caloric intake exceeds caloric consumption over a prolonged period, fat will accumulate. However, there are poorly defined genetic, hormonal, and psychological factors that predispose some people to progressively worsening obesity even though their dietary intake may not be excessive. In addition, caloric consumption is highly leveraged with exercise, and many patients are unable to increase their metabolic rate by exercise because of pain, stress injuries, time or motivation. Psychological problems such as compulsive eating disorders are another cause of obesity. And finally, obesity might be drug induced such as from the use of steroids for arthritis, sedatives for anxiety, or the use of antidepressants. In men the excess fat tends to accumulate in the abdomen , while in women it accumulates in the hips, thighs and legs as well as the abdomen.

Obesity is classified according to the body mass index (or BMI) expressed in weight in kilograms divided by height in meters squared (kg/m²) or BMI = wt kg/ht m². The following are two examples of the calculation of BMI.

The BMI categories are shown on Table 12.1. As both the duration of the obesity and its severity (as measured by BMI) increase, obese patients become susceptible to a whole host of serious medical problems (co-morbid factors).

Obese patients may have any combination of these conditions, but the most common are hyperventilation and respiratory distress lying flat, hypertension, and diabetes, type II. While obstructive sleep apnea might be suspected by the obese patient and/or family, confirmation requires a polysomnogram or sleep study which most patients coming for bariatric surgery will not have had. However, it is reasonable to assume that those obese patients who present with a history of restless sleeping, pronounced snoring or observed episodes of apnea during sleep may have a component of obstructive sleep apnea . Some obese patients develop what has been termed “a metabolic syndrome”, which is characterized by abdominal obesity, hypertension, increased fasting blood glucose levels, low levels of high density lipoprotein, increased serum triglycerides, and resistance to insulin. These patients are particularly prone to develop diabetes, and are at greater risk for death from their disease.

Most obese patients initially try to control their weight gain by subscribing to or enrolling in one or more of a variety of commercial dietary plans. These efforts may be combined with utilization of “over the counter” medications that work as appetite suppressants, metabolic stimulants or as lipase inhibitors that block the absorption of some fats. Most patients are temporarily successful on a variety of dietary plans. However, numerous well-done comprehensive studies have shown that weight recidivism in morbidly obese patients on a program of organized diet and exercise ranges between 95 and 98 % in as little as 6 months. To make matters worse, the amount of weight regained nearly uniformly exceeds the amount of weight lost. Currently bariatric surgery has been established to be the only durable treatment for morbid obesity, and the continually improving safety profile for this treatment has increased the number of patients seeking and being referred for surgery.

However, before any consideration is given to bariatric surgery, obese patients must be given a sustained, comprehensive trial of medical therapy. This would include a structured dietary intake, a regular program of exercise to the extent that that is physically possible, cessation of smoking, control of blood sugar, and psychological or behavioral evaluation and support. In our system, patients must be on this life-style changing regime for a sustained period of time and demonstrate an ability to lose weight before they are considered candidates for bariatric surgery. The goal of our program is not to achieve dramatic weight loss, but to demonstrate that permanent behavioral modification is possible. Bariatric surgery without behavioral changes carries a significant risk of weight recidivism despite the anatomical alterations. In those circumstances, the patient has assumed all of the risks associated with surgery, and achieved none of the benefits. Additionally, if a patient regains all of the weight lost after surgery, the co-morbid disease processes return for good; meaning if a patient has remission of diabetes or hypertension due to weight loss from surgery and then regains weight resulting in return of disease, even future weight loss will not improve those conditions a second time. This is the reason that our program adamantly enforces preoperative demonstration of lifestyle changes.