An upside to indulgence

How a milkshake may speed up your metabolism.

Gregory Nemec

Gregory Nemec

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Thinking that a food is rich and satisfying may actually cause your body to burn more calories and feel more full, according to a study by psychologists at Yale. Says doctoral student Alia Crum, lead author of the study (published in Health Psychology), “We’ve shown that our physiological response to food—the way our bodies metabolize the food—changes depending on what we’re thinking.”

Here’s how it worked: on two different occasions, researchers gave vanilla milkshakes to 46 subjects. The two milkshakes each person received were identical, at 380 calories, but one was labeled high fat and “indulgent,” with 620 calories, and the other fat free and “sensible,” with 140 calories. When the subjects drank the (supposedly) healthy shake, their levels of the hunger hormone ghrelin remained flat. But when the same subjects thought they were sipping a decadent shake, their ghrelin levels declined sharply after they drank it.

A drop in ghrelin, explains Crum, signals to the brain that “it can stop searching for food” and speeds up metabolism. The findings may help explain why some people (famously, the French) can eat rich food but remain slim. As usually calculated, the weight-loss equation—calories consumed versus calories burned—“just doesn’t add up,” says Crum. But “when we add the variable of mindset, it starts to make sense.” Our metabolism may speed up when we adopt what Crum calls “an attitude of enoughness”: when our mindset informs our guts that “we’re in good times: I don’t need to store fat.”

Does that dollop of “enoughness” allow us to trade our Slim-Fast “Strawberries N’ Cream” for a real strawberry shake? Not so fast. “It would be premature and probably wrong to suggest that eating rich foods is a good idea,” says study coauthor Kelly Brownell, an obesity researcher. But the findings have been enough to give Crum pause before reaching for an unsatisfying “diet” food.  

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