Calories on the Brain?

A postdoctoral scholar named Alia Crum decided to fool people in the name of research. She mixed up a vanilla milkshake and decanted it into two different kinds of packaging.

One set was labeled as a “sensible” shake with 140 calories per serving. The other was identified on the bottles as an “indulgent” shake with 620 calories.

The truth in both cases was that the shake contained about 300 calories. It was the same shake.

Volunteers were asked to drink the shakes. They had blood drawn three times:

  • before starting the experiment
  • after reading the label of their shake
  • after drinking the shake

Altogether, the experiment took a couple of hours — long enough for their brains to get the message that they had enjoyed a milkshake.

The subjects’ blood was tested for a particular substance called “ghrelin.” Ghrelin is a hormone in charge of telling your body that you’re hungry. It lets your brain know that you should eat something and also tells your stomach to begin getting ready for a meal. Ghrelin has also been linked to reward centers in the brain. You might say that ghrelin helps your body avoid losing weight, by reminding you to eat.

Usually, people who have not eaten for a long time have higher levels of ghrelin in their blood and people who have just eaten have lower levels. When Crum checked the levels of ghrelin in her subjects’ blood streams, she found a big difference between the ghrelin levels of people who thought they had been drinking a deliciously decadent shake and those who thought they’d had a light smoothie.

Those who thought they’d had 620 calories had much lower levels of ghrelin, while the ones who thought they’d taken in a mere 140 calories had little change in their ghrelin levels.

What conclusion can be drawn from this? Crum says it shows that physiological hunger depends not just on physical facts, but also on mindset.

For April Fool’s Day this year, think about tricking yourself into feeling more satisfied. You might be able to do that by giving up diet sodas, thinking of your salad not as a light lunch but as a delicious, satisfying meal, and indulging in a top-quality piece of decadent chocolate instead of a low-cal treat (the calories are probably the same). Feeling like you’ve indulged might keep you from feeling hungry.