Blame your brain for overeating


Put on a few extra pounds over Christmas? Wonder why you feel compelled to eat half a box of chocolates half an hour after finishing your second plate of turkey, dressing, mashed potatoes and gravy? Feel a little guilty?

Well, new research offers clues to one of the most baffling aspects of the eternal battle of the bulge: why we keep eating even when we’re full.

Short version: blame your brain.

When you’re hungry, food looks more appealing than when you’re not: hence the old adage about never shopping on an empty stomach.

Previous research has suggested that ghrelin, a hormone the body produces when it’s short of calories, may act on the brain to trigger this behavior. Now new research suggests that this same hormone–increased levels of which have also been linked to the pleasurable feelings people get from alcohol or cocaine–may also come into play to trigger overeating.

Or, as Dr. Jeffrey Zigman, assistant professor of internal medicine and psychiatry at the University of Texas Southwestern, puts it, “There may be situations where we are driven to seek out and eat very rewarding foods, even if we’re full, for no other reason than our brain tells us to.”

Rewards, in psychiatric terms, are things which make us feel better: they’re pleasurable, they motivate us to work to obtain them, and they even help reorganize our memory so we remember how to get them.

To discover why people who are already stuffed with food nevertheless go ahead and order a massive dessert, Dr. Zigman and colleagues conducted two tests.

First, they evaluated whether fully sated mice preferred a room where they had previously found high-fat food over one that had only offered ordinary bland mouse-chow. They found that when they gave the mice ghrelin, they strongly preferred the high-fat room. Those that were not given ghrelin showed no preference.

That appears to indicate that, thanks to ghrelin, the mice remembered how much they had enjoyed the high-fat food and where to get it. Even though the room was now empty, they still associated it with something rewarding.

Blocking the action of ghrelin reduced the amount of time the mice spent in the high-fat room.

In the second test, the researchers watched to see how long mice would continue to stick their noses into a hole to receive a pellet of high-fat food. The animals that received ghrelin did so far longer than their non-ghrelinated cousins.

“But wait!” I hear you cry. “I am not a mouse. I am a human being!”

Well, sure, but there’s a reason mice are always being used as medical stand-ins for humans in laboratory tests: we have the same type of brain-cell connections, the same type of hormones, and the pleasure centers of our brains are similarly structured.

Does this let you completely off the overeating hook? No, because we are capable of resisting these kinds of urges: we do it all the time, or else we’d never get anything else accomplished. So even though the dessert looks tempting, you don’t have to eat it…but it does take a conscious effort, and sometimes that’s in short supply.

Brian Wansink, a behaviorial scientist at the Cornell Food and Brand Lab, has listed a few strategies to avoid giving in to ghrelin’s urges and eating unconsciously.

For one, use smaller plates and serving bowls. The bigger the plate is, the larger the servings tend to be, 25 to 28 percent larger on average.

Also, don’t watch TV while you eat. When your conscious mind is distracted, your unconscious mind takes over. People watching TV typically eat 40 percent more food.

And finally, don’t go back for seconds. People at a buffet who put everything they’re going to eat on their first plate, dessert included, eat 14 percent less than those who put smaller portions on their plate, then go back for more.

I know, I know. For this Christmas, all this information is too little, too late.

But it’s almost New Year’s, a time for regret and resolution.

And if you fall off of the eating-less wagon in a few weeks…well, tell everyone you can’t help it, you have a hormonal condition.

The fault lies in our ghrelin, not ourselves, that we are gluttons.

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