That mellow feeling that settles in when you kick off your shoes, pour yourself a drink and start making dinner should come with a warning: Overeating ahead.
Don't hear it? That would be your brain's reward system -- the primitive structures that prime our drives for sex, food and addictive substances -- overriding the message.
For many who have tried to lose weight while clinging to that hallowed ritual of the aperitif, this may come as no surprise. But a new study finds clear evidence that consuming alcohol while in an atmosphere suffused by cooking aromas heightens activity in the hypothalamus, and throughout the brain's reward system. The result, in most cases, is increased consumption.
That disheartening news about "the aperitif effect" comes in the July issue of the journal Obesity, published by the American Obesity Society.
In a study conducted by researchers at the Indiana University School of Medicine, 35 healthy, non-obese women signed up to attend two experimental sessions. At each, they got breakfast, and roughly eight hours later, a late lunch.
An hour or two before lunch, each woman had her brain scanned to discern how she responded to olfactory cues -- food related and otherwise. While lying in a scanner, half of the women in each session were administered an IV alcohol solution tailored to induce a pleasant buzz, while the other half got saline solution only.
Every few minutes, researchers pumped concentrated puffs of cooking odors -- of simmering beef and of tomato-based meat sauce for pasta -- into those spaces. For comparison, they also pumped in an odorant representing a neutral non-edible item.
Compared to women dosed with an IV saline solution, those who got a dose of alcohol in their IV responded to the smell of meat sauce wafting through the air with higher levels of activity in the hypothalamus, a central node of the brain's reward system. A pre-lunch cocktail had no such differential effect on how the women's brains responded to a neutral odor.
Two-thirds of the women then went on to eat more -- most of them significantly more -- after they got the alcoholic IV cocktail than they would eat when they got saline alone.
There were two curious and counterintuitive twists in these findings: First, roughly a third of women actually ate less after they got a bolus of alcohol. And second, the women who got the pre-meal cocktail were found to have lower levels of the hormone ghrelin circulating in their blood. Ghrelin normally signals the brain that hunger has been sated, reducing appetite. And yet, these women, on average, showed larger appetites.
The authors acknowledge that it's hard to say what those findings mean. Those with advanced alcoholism generally experience a loss of appetite after consuming alcohol. Other studies suggest that overweight women respond to alcohol with greater consumption than do normal-weight women. Perhaps a woman's response to an aperitif says something about her propensity for weight gain or alcoholism. Or perhaps, alcohol simply plays havoc on appetite signaling between gut and brain, and within the brain.
For the record
June 26, 12:41 p.m.: An earlier version of the caption on this post incorrectly credited the photo to Haley Bemiller of the Chicago Tribune. Bob Fila of the Chicago Tribune is the photographer.