Blame the brain, women, if you just can’t resist that pecan pie. A new study from Brookhaven National Laboratory has found that although men can control their brain’s response to food, women can’t. To discover this fact, researchers used brain-imaging techniques while exposing subjects to tempting treats.

Now here’s a scenario that seems one step away from torture: The 13 women and 10 men in the study fasted for 20 hours, then got into hospital robes and submitted to PET scans — lying on their backs with their heads inside the scanning tubes– while the scientists reached inside and held up food to the subjects’ noses. But not just any food — subjects were asked to list their favorite treats, and that’s what they got to sniff — warmed if necessary to enhance the aroma. But the subjects could only smell and not taste –as if PET scans aren’t distressing enough without the deprivation. Watch this video clip to witness the inhumanity firsthand.

Seriously, though, the results yielded interesting data: When asked to inhibit their hunger response, both genders “reported” diminished appetite, but the brain scans “told” a different story. As study director Gene-Jack Wang tells it, “Even though the women said they were less hungry when trying to inhibit their response to the food, their brains were still firing away in the regions that control the drive to eat. In contrast, men’s brain activity decreased along with their self-reports of hunger during the scan when they were asked to keep their hunger in check.”

The researchers believe that since women have a harder time subduing their brain’s hunger response, it makes sense that they’d also have a greater challenge in dieting and losing weight. Dr. Wang says, “This decreased inhibitory control in women could be a major factor contributing to the observed differences in the prevalence rates of obesity and eating disorders such as binge eating between the genders and may also underlie women’s lower success in losing weight while dieting when compared with men.”

The only problem with his hypothesis is that, in fact, obesity rates have become fairly equalized between the genders. At most recent count, 24 percent of women were obese, versus 23 per cent of men; another CDC sponsored study in 2007 found that men already had surpassed women by two percentage points. Although six or seven years ago far more women than men were obese, men now are packing on the pounds faster than women; and The Department of Health predicts that at current rates, by 2010 men will surpass women with around 6.6 million obese men in the U.S. compared to six million obese women.

Why would men be surpassing women in obesity if men, theoretically, can control the urge to eat more readily than women can? According to Karen Miller-Kovach, chief scientific officer for Weight Watchers International and author of She Loses, He Loses, it’s because women recognize when they’ve gotten fat more readily than men do. “Overweight women are more likely than overweight men to accurately assess their own condition,” she says.”

This appears to be a kind of reverse anorexia, since anorexics don’t perceive the fact that they’re losing too much weight and obese men don’t seem to notice that they’re putting it on. And given the fact that women succumb to anorexia far more often than men (90 percent women versus 10 percent men), perhaps there is some gender-specific mechanism that fires one way for women, and another way for men. Considering that men at least equal women in the obesity crisis now, perhaps the next study should do brain scans to determine why men fail to see that they’ve gained weight.

In any event, according to Miller-Kovach, “…once concluding that they need to lose weight, men more aggressively attack the problem and are more likely to stick to a plan.” And so men tend to have more success than women in losing weight once they choose to do so, and the recent study indicates why that’s the case.

Now, if you’re not thoroughly confused yet, there’s more.

Scientists at Brookhaven are cooking up ways to address the problem. Having now gathered “new insight” about how the brain responds to food, Dr. Wang notes, “Our findings may help us understand the neurobiological mechanisms underlying the ability to control food intake, and suggest new pharmacological methods or other interventions to help people regulate eating behavior and maintain a healthy weight.”

Ah, the pharmaceutical deus ex machina to the rescue — another pill for women, perhaps? In fact, the authors of the study note that the reason women might have trouble turning off the hunger mechanism may be estrogen-related, as sex hormones are known to influence both eating behavior and weight. Then again, if you’re female and pharmacologically phobic, you try a more fundamental approach — rather than searching for yet one more magic bullet.

:hc