A study suggests that convincing yourself that food has a higher calorie content may suppress your appetite and help you lose weight.
Alia Crum and her colleagues at Yale University gave 46 healthy volunteers the same 380-calories milkshake. However, some participants were told it was a low-calorie choice, whilst others were told it was high in calories.
The 'low-calorie' bottle of the shake claimed it to have zero percent fat, zero added sugar and be only 140 calories. Whilst the 'high-calorie' bottle was labelled as 'indulgent' and accounted to 620 calories.
The team measured levels or ghrelin before and after volunteers drank the shake. Ghrelin is a hormone released by the stomach when we are hungry.
"It also slows metabolism," Crum said, "just incase you might not find that food."
Once you have a big meal after you ghrelin rises, your level proceed to drop again, telling your brain that you've had enough to eat and it's time to start metabolising, in order to burn the calories ingested.
Meaning that when we have something like a small salad, ghrelin levels don't drop as much, and metabolism isn't triggered in the same way. For a while, scientists believed that ghrelin levels change in response to the nutrients in your stomach.
But Crum's study pushed back on that belief.
If participants believed they were drinking the high-calorie shake, the body responded as though the participants had consumed more than they actually had.
"The ghrelin levels dropped about three times more when people were consuming the indulgent shake (or though they were consuming the indulgent shake)," Crum said.
However, it doesn't mean the nutrients doesn't matter, but Crum suggests that the metabolic model may need to be rethought.
"Our beliefs matter in virtually every domain, in everything we do," Crum says. "How much is a mystery, but I don't we've given enough credit to the role of our beliefs in determining our physiology, our reality."
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