Scientists find mind over matter important in dieting

BRAINPOWER is more important in dieting than scientists realised — not just in battling cravings but in physically changing the body’s reaction to the intake of food, according to a new study.

Whether or not we consider a food to be healthy has a big impact on a protein our bodies release to control metabolism and appetite, a researcher discovered. Participants who thought they were drinking a calorie-packed shake showed much greater and quicker spikes in a gut hormone, making them feel full faster, than those who were drinking what they thought was something healthier.

“When you are dieting, you want to eat fewer actual calories, but the mindset of ‘Okay, I’ve got to eat sensibly, I’ve got to eat low fat,’ ... regardless of what you are eating, is actually counter effective,” study researcher Alia Crum of Yale University said.

“It’s telling your body, ‘I’m not getting enough,’ which relays back to your brain, ‘I’m not getting enough.’”

The 46 participants in the study were given two different taste tests a week apart.

In one test, they drank a shake labelled “health shake”, which they were told had 140 calories. In the other test they were given an “indulgent shake”, which they were told contained 620 calories. Both were the same 360-calorie shake.

At three times during the taste test (beforehand, after seeing the label and after drinking the shake) the researchers sampled the participants’ blood, testing it for a protein called ghrelin, a gut hormone that plays an important role in appetite.

In general, ghretin levels increase before eating. They drop when the gut senses food; the quicker these levels drop, the quicker you start to feel full. So the less ghrelin you have, the less you want to eat.

Crum found that when participants imbibed the “indulgent” shake, ghrelin levels dropped much quicker than when they downed the shake labelled healthy.

The finding suggests that when people eat diet or health foods (something labelled low calorie or low fat), their bodies respond differently than when they indulge in seemingly unhealthy foods. This could mean they take in more calories from healthy foods.