News Stories

Why We Crave Sweets

Is one of your resolutions (NOTE: Subscribers can still listen to this show) for 2013 to lose weight? If so, one of your main problems is probably sweets--why do we crave them, and what can we do about this? (NOTE: Anne Strieber's diet book, now reduced to $3 from $5, has some good advice about this).

fMRI brain scans show that food cravings activate the same reward circuits in the brain as cravings for drugs or alcohol. More women have food cravings than men (perhaps because of pregnancy?) and younger people crave sweets more than older people do. And women aren't happy when they give in to them: 85% of men say they found giving in to food cravings satisfying; but only 57% of women say they did.

About half of the women in the US say they crave chocolate when their monthly menstrual period arrives, but researchers haven't found any link between food cravings Psychologists think women may be "self-medicating," because sweets and carbohydrates release the "feel good" hormone serotonin into the brain.
Researchers used to assume that food cravings were the body's subconscious efforts to correct nutritional deficiencies: craving a steak could mean you were low on protein or iron, and chocoholics might be low on magnesium. But few people crave green leafy vegetables.

Cultural factors may also be involved: while US women crave chocolate, Japanese women are more likely to long for sushi. And in Egypt, only 1% of young men and 6% of young women report a craving for chocolate.

In the September 18th edition of the Wall Street Journal, Melinda Beck quotes psychologist Julia Hormes as saying, "Many other languages don't have a word for 'craving.' The concept seems to be uniquely important in American culture."

Women who reported the most cycle-related cravings also have a history of dieting, eating disorders and high body mass indexes. Hormes says, "These seem to be women who think, 'I shouldn't have any chocolate at all,' but then they give in and have the whole bar. The more they try to restrict it, the more they craved it."

So if we're fat, should we blame our brain? Well, it turns out that new nerve cells formed in a select part of the brain could control how much you eat and thus how much you weigh. The part of the brain called the hypothalamus, which is associated with a variety of bodily functions, including sleep, body temperature, hunger and thirst, continually produces new neurons. This process is called neurogenesis.

Neuroscientist Seth Blackshaw says, "People typically think growing new neurons in the brain is a good thing--but it's really just another way for the brain to modify behavior."

When researchers fed mice a diet of high-fat chow starting at weaning and looked for evidence of neurogenesis at several different time points, they found that very young animals showed no difference compared with mice fed normal chow. However, neurogenesis quadrupled in adults that had consistently eaten the high-fat chow since weaning. These animals gained more weight and had higher fat mass than animals raised on normal chow, meaning that what you eat as a kid can produce weight gain later.

So what can we do about our cravings? Food psychologist Marcia Pelchat suggests setting a timer for 30 minutes whenever a craving comes on, and busy yourself with something else until the timer goes off. At that point, the craving may have passed (this is Anne Strieber's advice too!) Beck quotes her as saying, "If you can at least delay eating the craved food, you can weaken the habitual response."

And the longer people stave off their food cravings, the weaker they become.



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