There are two basic types of weight loss surgery - restrictive surgeries and malabsorptive surgeries (and also surgeries that are a combination of both procedures). Each helps with weight loss in different ways.

• Restrictive surgeries (like adjustable gastric banding) work by physically restricting the stomach's size, limiting the amount of solid food you can eat. A normal stomach can hold about three pints of food. After weight loss surgery, a stomach may only hold one ounce of food, although over time it may be able to hold two or three ounces of food.

• Malabsorptive surgeries (like gastric bypass) work by changing the way your digestive system absorbs food. This type of weight loss surgery is more complicated. The surgeon removes parts of your intestine, creating a shortcut for the food to be digested. This means that fewer calories get absorbed into the body. The combined malabsorptive/restrictive surgery also creates a smaller stomach pouch, which restricts the amount of food you can eat.