There are two main reasons why we consider weight loss surgery (WLS). The first is that other methods for controlling weight have not been effective, and the second is that obesity has serious consequences for health. In general, the more severe the obesity, the more severe the consequences. Obesity has been shown to correlate with a shorter life-span.
1) Other methods to lose weight are not effective.
Anyone considering WLS should have tried to lose weight without surgery. However, the likelihood that a person will be able to keep off enough weight is slim. Fewer than 3 percent of morbidly obese people who go on a diet, even a medically supervised one, will be able to keep off at least half of their excess weight. In theory any one can lose and keep off all of their excess weight, but in reality, this is rarely seen.
2) Obesity has serious health problems and risks.
Many conditions are known to be associated, worsened, or caused by obesity. For example:
Diabetes, hypertension, sleep apnea, arthritis, depression, gastro-esophageal reflux (GERD), dyslipidemia (high cholesterol and/or triglycerides), edema, urinary incontinence, endometrial cancer, and coronary artery disease.
Even if an obese person does not have any known problems yet, they are at risk for developing all the conditions above, other conditions, and early mortality.