We’ve all heard it before: perception is everything. People form opinions about us based on our actions towards them, filtered through their own inbuilt prejudices and biases. Our views about others are similarly determined. We also know that two people will often view the same event in completely different ways. Now research from Yale University suggests that our perception of the food we eat could influence our ability to lose weight.
A key factor in appetite regulation is a powerful hormone called ghrelin (also called the “hunger” hormone). Ghrelin stimulates the appetite, so blood levels normally spike before meals and drop afterwards. People given ghrelin injections become voraciously hungry and, if given free access to a buffet, will eat 30 percent more than they normally would! Studies also show that dieters who lose weight and then try to keep it off, produce more ghrelin than they did before dieting, which helps to explain why most diets don’t work – or at least not for long.
In the Yale study, participants were given a 380 calorie milkshake under the pretence that it was either a 620 calorie “luxury” milkshake or a 140 calorie “healthy” shake. Researchers found that study participants who believed they were drinking the high-fat, high-calorie shake had a rapid fall in ghrelin levels after drinking it and felt full. On the other hand, those who drank what they believed to be a “healthy” shake, showed little change in ghrelin levels and still felt hungry. These responses were close to what would have been expected had the study volunteers actually been given a 620 or a 140 calorie milkshake.
These results are a striking illustration of the extent to which our beliefs alone can result in real alterations to our body chemistry. In effect, the brain was tricked into either feeling full or feeling unsatisfied, on the basis of an entirely incorrect perception. Along with other studies, this experiment gives important insights into how the mind and the body work together to determine our responses to food. So maybe the idea of thinking ourselves slim isn’t that silly after all.
Dr David Ashton
30th August 2011
A version of this article appeared in Reader’s Digest magazine.
