Weight loss surgery can help people with major health problems lose weight. Sometimes weight cannot be lost simply from dieting. Weight loss surgery generally helps by restricting how much a person can eat, and the rate of digestion.

Weight loss surgery is usually performed on people who are morbidly obese. These people have a Body Mass Index (BMI) of 40 and above. There are four main types of weight loss surgery.

1. Stomach Stapling

The most common form of weight loss surgery is stomach stapling, or vertical banded gastroplasty. In the surgery, both a band and a staple are used to create a small stomach pouch. This form of weight loss surgery limits the amount of food a person can eat and slows the passage of food.

2. Adjustable Gastric Band

A similar form of weight loss surgery is the adjustable gastric band, where an inflatable silicone band is implanted around the top portion of a person's stomach. This restricts the movement of food into the bottom half of the stomach and makes the person feel full.

The band is adjustable using a small port to the band, where saline solution can be injected. The band can be inflated with the liquid. It usually takes about three to five fills before a person reaches the level where they can lose weight.

3. Gastric Bypass Surgery

Gastric bypass surgery is a risky form of weight loss surgery, but when successful can produce rapid results. In this procedure, the stomach is stapled to form a small stomach pouch, while the rest of the stomach is completely stapled closed and divided from the stomach pouch.

4. Duodenal Switch

The last form of weight loss surgery is the duodenal switch, or bilio-pancreatic diversion. The procedure is known as a malabsorption procedure because it also changes the digestive system. Food usually reaches the digestive juices towards the middle or end of the small intestine, meaning there is less breakdown of food. This form of weight loss surgery can be very successful, but because the body does not absorb nutrients properly, patients have to take vitamin and mineral supplements.