October 03, 2010
Weight Gain Reduces Food Pleasure
Eric Stice, Cara Bohon, and other researchers find that as a group of women gained weight their brains showed less signs of pleasure under a brain scan when eating sweet foods.
In a new study published Sept. 29 in the Journal of Neuroscience, Bohon fed milkshakes to a group of overweight women and monitored their brains' response to the combination of Häagen Dazs ice cream and Hershey's chocolate syrup. She used functional magnetic resonance imaging, or fMRI, to measure changes in brain blood flow and found that the sugary treat stimulated activity in the striatum. The striatum, located deep inside the brain, is a primitive mass of brain cells that, among other things, release feelings of pleasure when we eat foods we like.
Six months later, the women returned and repeated the experience. Some had gained a few pounds. The more weight they had gained during those months, the less their brains responded to the second milkshake, as compared to the first.
You can see a vicious cycle here that the researchers liken to cocaine addiction: The need for a bigger dose to get the same pleasure. In this case the need for the bigger dose causes weight gain which causes the deadening of taste response.
So how to restore taste sensitivity? I'd like to see a study done on whether weight loss alone fully restores taste sensitivity.
I doubt restoring taste sensitivity would help; What's really needed is something besides food that supplies positive reinforcement. Given a variety of rewarding options, reducing the reward from eating as one gains weight would actually function as a negative feedback mechanism to control weight, by causing you to divert to more rewarding behaviors. Reduced reward is only going to increase a behavior if you don't have other behavioral options.
The obese need more options for reward. Problem is, obesity tends to shut off other routes to reward.
Sugar is bad, in any form - raw, natural, organic, your brain can't tell the difference. And the addiction is real, as you noted. IF (all caps on purpose) you can go sugar-free (non-caloric sweeteners too) for more than a month, you realize how sweet everything we eat is. In my practical experience, 86% dark chocolate is sweet enough to nip the desire once sugar free.
Sugar or some derivative (HFCS, honey, syrup) is in nearly every packaged food. Nasty.
"What's really needed is something besides food that supplies positive reinforcement."
-- Or we need an easier way to get a negative feedback for eating badly or too much. Gastric bypass does this very well (pain & vomiting), but there are some serious risks and downsides to the surgery.
@Brian - the same can be said for salt in the current "western" diets. Given that salt and sugar tend to mask each others tastes, it's no wonder that so much prepared/processed food has excessive amounts of both.