WEIGHT-loss surgery not only rids people of their fat, it may also abolish alcohol cravings.
Some people choose to lose weight by going under the knife to decrease the size of their stomach. One such surgery - the Roux-en-Y procedure, or "gastric bypass" - involves stapling the stomach to leave a small pouch at the top, which is then connected to the small intestine. Food then bypasses most of the original stomach and a chunk of the intestine too. This significantly reduces the amount of food a person is physically able to eat and the amount of nutrients they can absorb.
Jon Davis and colleagues at the University of Cincinnati in Ohio collected outcome data on 80,000 people in the US who had had weight-loss surgery, including Roux-en-Y. They found that only those who had the Roux-en-Y procedure reported drinking fewer alcoholic drinks after the surgery than before. People who underwent other types of surgery, such as a gastric band, saw no change in alcohol use.
To investigate further, the team carried out Roux-en-Y surgery on rats bred to prefer alcohol, and found that they also stopped drinking it afterwards. This held even when the team used established psychological experiments to associate alcohol with a reward (Biological Psychiatry, DOI: 10.1016/j.biopsych.2012.01.035). "It's a real phenomenon," says Davis.
His team thinks that the sudden drop in alcohol consumption may be down to a hormone called GLP-1. When partly digested food hits the middle section of the small intestine, called the jejunum, GLP-1 is produced. This triggers the production of insulin, which in turn acts to lower blood glucose levels. After Roux-en-Y surgery, this part of the intestine is much closer to the stomach, causing it to be exposed to a much higher level of nutrients than it normally would be. Davis thinks this may be ramping up the production of the hormone.
It is this extra GLP-1 that may be influencing cravings, he says. The hormone is thought to play a role in limiting how much food we eat once we are full. "GLP-1 travels through the blood to get to the brain, where it is thought to stimulate an aversion to food," says Davis. He thinks it may be eliciting a similar effect on alcohol consumption because alcoholic drinks can contain lots of calories.
Carel le Roux at Imperial College London says the finding fits with his own results that suggest weight-loss surgery not only reduces hunger, but also the reward associated with food. He says it may be that "the surgery makes you less bothered about your favourite 'sin', whether this is food or alcohol".
Davis's group is now testing a diabetes drug in mice that acts to increase levels of GLP-1, in the hope that it might help alcoholics give up alcohol.
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Weight-loss surgery reduces desire for alcohol
