But weight-conscious people should heed the humble rat, which stays trim by instinctively cutting calories when indulging in alcoholic drinks, say researchers at the University of Florida's psychology department and the Evelyn F. and William L. McKnight Brain Institute.
Rats also know how to say no to the brew, stopping at what would amount to two or three drinks in most people, according to a paper in the current issue of Pharmacology, Biochemistry and Behavior. Many people ignore the same instinct -- a shortcoming that can spell dietary disaster.
"Behavior in humans is complicated because we are bombarded by social and marketing factors that stick food in front of our face every which way we turn," said Neil Rowland, a professor of psychology who studies the neural mechanisms of obesity, eating disorders and alcohol abuse. "It's difficult to say no."
People cannot simply cut food calories while they're drinking without also considering the effect it will have on their sobriety, researchers caution. But it's also important that they consider the effect that drinking has on their waistlines.
An estimated 65 percent of U.S. adults and 16 percent of children and adolescents are either overweight or obese, according to the 1999-2002 National Health and Nutrition Examination Survey done at the Centers for Disease Control and Prevention.
Furthermore, a CDC analysis shows Americans consume more calories than they did 30 years ago. On average, women increased their daily calorie consumption 22 percent between 1971 and 2000, from 1,542 calories per day to 1,877 calories. During the same period, men increased their calorie intake 7 percent, from 2,450 calories per day to 2,618 calories.
UF scientists, who monitored the food, fluid and alcohol intake of six male and five female rats over several days in three separate experiments, said their work supports the idea that people don't consider the nutritional aspects of beer, liquor, mixed drinks and even soft drinks.
"I think it tells people to watch what they are eating," Rowland said. "Outside factors are overriding the natural signals that we've eaten enough or have had too much to drink. That's not a novel concept, but it is a good description of what's happening. Some folks stand by the chip bowl and consume a lot of food with their alcohol, when they need to think about drinks in general as components of their energy intake. The rats can count these calories very well. People can be educated to think about these internal signs that the rats are so aware of, and eat one less sandwich and have one less drink."
More than 50 years ago, scientists noticed that Americans think of alcoholic beverages as a drug, not as a source of nutrition, Rowland said. Since then, researchers have studied caloric compensation in humans and in animals, noting that rats instinctively manage their weight by not eating as much when they receive calories from alcohol. Scientists believe people may ignore the internal stop signs. But the rodent imbibing experience in previous experiments didn't parallel the human one. Rats would drink the ethanol and water that scientists mixed for them only if nothing else were available -- not the typical atmosphere you'd find at a tailgate party. In addition, people usually prefer a variety of ingredients in their drink selections, which makes the matter of assessing calories far more complicated.
"Most humans consume alcohol in a mix with something else, like a beer or a margarita, which has lots of other components in it," Rowland said. "If the body has to count calories, the mechanism must be complex enough to analyze more than just one thing. The point was to develop in rats a way in which they willingly consume relatively large amounts of alcohol, and to see if they could still manage calories."
In the current study, UF researchers made alcohol more palatable by adding it to decarbonated, non-alcoholic beer, which also allows scientists to precisely measure the alcohol content. In a separate test they presented the alcohol mixed into a sweet gelatin. Both male and female rats cut back on their calories from food and maintained a consistent intake of overall calories during the experiments, even with access to plenty of food, fresh water and palatable alcohol.
"The important thing is that the rats were able to accurately compensate for their calories when they electively consumed alcohol," said Allen Levine, head director of the Minnesota Obesity Center and a professor of food science and nutrition at the University of Minnesota. "But people have access to a tremendous variety of foods, and because of that, we don't compensate well. We have to use volitional control -- willpower -- to control our caloric consumption. This isn't a big deal for some people, but for others, who might be addicted to alcohol or food, it is a problem."
Additional investigation of the long-term effects of alcoholic nutrients in rats may shed more light on the internal and external signals that regulate caloric intake in humans, researchers say. But until then, the battle of wills this Sunday won't just be on the playing field, but in the buffet lines.