Complications of obesity. Obesity impairs the function of many organ systems in the body, such as the circulatory system. The risk of serious medical conditions increases with higher BMI values. In addition, obesity reduces quality of life, complicates recovery from surgery, and causes premature death. There is also discrimination against obese people. Obese people often have less social success than thinner people and find it harder to get jobs.

Effect of weight loss. Weight loss in obese people improves or eliminates obesity-related medical conditions and improves quality of life. Many of the results are directly related to the amount of weight lost. Beneficial health effects are even seen after modest weight losses and increase with greater weight loss. Obese people do not have to become lean to benefit from weight loss. Weight loss of as little as 10 percent of total body weight can produce significant health benefits, even in people who remain obese.