How surgery works

The human body lays down fat stores if the calories in the food you eat exceed the energy you burn up. There are a number of complex processes which the medical profession are only just starting to understand that seem to contribute to increasing obesity - the appetite mechanisms go wrong and you continue to eat even though you do not need the calories. And of course, once your body is carrying the extra weight, it becomes harder to be physically active which would help to regulate your weight.

Obesity surgery works by helping to reduce the number of calories that are available in your body. There are two ways this can be achieved surgically:

  • Restriction - by reducing the size of the stomach, only small meals can be eaten and the appetite is satisfied
  • Malabsorption - by bypassing part of the small intestine, less calories from food are absorbed by the body

The operations that work by restriction are:

The operations that work by a combination of restriction and malabsorption are:

There are different benefits and risks associated with each of these operations which are discussed more fully under each link.

In the UK, the National Institute for Clinical Excellence (NICE) makes recommendations to the NHS about where and when surgical procedures should be used. In 2002, they undertook a comprehensive review of all the information available about obesity surgery, including the results of all the studies conducted around the world. NICE recommended that surgery should be an option for patients who have a BMI over 40 kg/m2 (or 35 kg/m2 if they also have an obesity–related disease). They did not distinguish between the different surgical procedures available, recommending that choice be made jointly by surgeon and patient. We entirely agree with this and remind you that although the type of operation is an important factor in how much weight you will lose, a big part of the treatment is your willingness to change your eating and lifestyle habits to ensure you have the most successful outcome.

      Click here to read the full NICE guidance on surgery for morbid obesity.

      Other specialist procedures

      Although not strictly falling into the same class as the surgical operations that have been discussed in this section, it is important to mention intragastric balloons and intragastric stimulation, two new methods of weight loss that are becoming more widely available.

      Neither of these is including in existing guidance published by NICE, the UK government’s healthcare advisory body, so they are not readily provided on the NHS. However a growing number of surgeons are offering these procedures where they have been able to obtain special funding, are undertaking research on them, or offer them to private patients.