In the U.S., obesity is a leading cause of mortality, disability and rising health care costs. But many side effects, both positive and negative, accompany weight loss. Because of the risk for negative side effects, it's important for one to be well-educated on nutrition and exercise before beginning a weight-loss program.
Positive Side Effects
The most significant side effect of weight loss is the decreased risk of disease. According to the Obesity Society (obesity.org), 90 percent of type 2 diabetes patients are overweight due to their bodies being unable to properly control blood sugar by using insulin. The risk of certain cancers also decreases with weight loss, including kidney, endometrial, colorectal, gallbladder, thyroid and postmenopausal breast cancers (see Reference 1).
Increased energy is a common side effect of weight loss. With any exercise regime, one replaces fat with muscle. You feel stronger and lighter. Everyday tasks that once required large amounts of energy become easier. Additionally, because muscle cells burn more calories than fat cells, those who exercise will burn more calories throughout the day, even while their bodies are at rest (see Reference 2).
Weight loss often leads to increased self-esteem levels, especially in children. Children who are overweight are also more likely to be overweight as adults. Both children and adults can better focus on their strengths and positive qualities when they are not constantly worrying about weight issues (see Reference 3).
The American Journal of Clinical Nutrition (AJCN) reports that weight loss in women can lead to a healthier pregnancy. Infants of overweight mothers more often require admission to neonatal intensive care units, reports the AJCN. Obese women who give birth are at high risk of Caesarean deliveries. Women of normal weight have on average, a lower cost of prenatal and postnatal care.
Negative Side Effects
One of the most common negative side effects is eating disorders (especially among females), as weight loss can become obsessive and continue even after the person has reached a healthy weight. If too few calories are consumed, a person may become chronically fatigued and experience hair loss and dizziness. More serious side effects of eating disorders include depletion of important nutrients, mood disorders, hospitalization or even death.
Stretch marks and loose skin are a negative side effect of weight loss. The American Society for Aesthetic Plastic Surgery reports that large amounts of weight loss may cause abdominal skin to become flaccid, requiring surgical procedures such as abdominoplasty (to tighten weakened skin muscles in the stomach). Stretch marks may also appear during and after weight loss.
While there are both positive and negative side effects of weight loss, it is important for people to follow a healthy diet and exercise program, abstaining from fad diets and unrealistic expectations. Rapid weight loss can cause more harm than good, as one's metabolism will weaken over time. One will likely gain back the weight just as quickly as it was lost.