Gastric Bypass Surgery

What is gastric bypass surgery?

Gastric bypass has been described as the ‘gold standard’ weight control operation and has been the most frequently performed weight loss surgery procedure worldwide. It is the operation to which all other bariatric procedures are compared, and it has the best – and best known – long-term results.
The operation is truly a bypass of the stomach. Most of the stomach is bypassed (unlike the gastric sleeve, where most of the stomach is removed) so that food eaten goes into a small gastric pouch (15-30mL) and then into a loop of the small bowel (the jejunum) for digestion. Gastric bypass surgery, unlike a sleeve gastrectomy, is reversible. The stomach and bowel can be reconnected, although this requires another operation.

There are several different types of gastric bypass surgery available: the Roux-en-Y Gastric Bypass (banded or unbranded), the Mini Gastric Bypass and the One-anastomosis Gastric Bypass (banded or unbanded).

How the gastric bypass surgery causes weight loss

The gastric bypass surgery itself does not make you lose weight. Overeating is limited by the new small and tight stomach. Too much food causes discomfort and vomiting. If possible, your surgeon may put a silicone ring around the stomach, which helps prevent the stomach from stretching in the future (the banded bypass).

Satiety (being satisfied early in a meal) is induced by the small stomach and through the ‘switching off’ of the hormones that cause hunger. Many patients go for months before they have any recognisable hunger sensations, and they often have to remind themselves to eat.

The operation often causes intolerance to sweets and high-density carbohydrates as well as fatty, oily food. These foods run quickly into the small bowel and cause unpleasant symptoms called ‘dumping’. There is trivial malabsorption of fat, as the food eaten is initially not mixed with bile and pancreatic juice (there is no protein or carbohydrate malabsorption).

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Am I a candidate for a gastric bypass?

As with all weight loss surgeries, gastric sleeve surgery should only be performed on people with a BMI greater than 40, or those with a BMI over 35 with other medical co-morbidities such as diabetes or high blood pressure.

Occasionally patients with BMI under 35 may also undertake this operation; however, the balance between risk and benefit is harder to gauge. Patients who are lighter than this run the risk of losing weight but at the expense of complications that can make them worse off. Other weight loss therapies should have been tried beforehand but have been unsuccessful.

Patients with eating disorders such as binge eating or a nocturnal eating disorder, and patients who habitually graze or emotionally eat, need to seek treatments for these disorders as well, otherwise, the surgery will fail after being initially successful.

Advantages of gastric bypass surgery

  • Generally, the gastric bypass requires a short hospital stay of 2–3 days, and patients find it OK to return to work by about two weeks.
  • The advantages of gastric bypass surgery are clear; it has been proven to significantly reduce a patient’s weight not only immediately following the surgery, but for up to 20 years afterwards.
  • Patients can lose up to 30 – 50% of total body weight as a result of gastric bypass surgery. Patients have demonstrated that with this form of surgery it is easier to maintain long-term results.
  • With such significant weight loss, patients will then see other health benefits as a result such as Type 2 Diabetes going into sustained remission, ease of joint pain such as knees, ease of breathing and other health benefits.

Drawbacks of gastric bypass surgery

  • As with every surgery, this operation poses risks to the patient. However, the operation is invariably performed laparoscopically which means less chance of infection and much quicker recovery times. But of course, this can vary from case to case. Most patients recommended for this surgery will fail to lose a significant amount of weight without it and can face even more serious risks to their health long term.
  • Gastric bypass surgery affects how your body absorbs the food you eat, so there is a risk of various deficiencies occurring. All patients having bypass surgery need a minimum of a daily multivitamin and at least 6 monthly vitamin B12 injections. Other items including Vitamin D, calcium and iron will be needed by many patients.
  • Gastric bypass surgery can also result in a condition that is referred to as “dumping syndrome”; this is when food, in particular sugar, moves through the digestive system too quickly and can cause nausea, diarrhoea and reflux. This is why patients are advised not to eat foods with a high sugar content following surgery.

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