Consumers need to become more acutely aware of their 'internal stop signs' that could put the brakes on over-consumption.
Scientists at the University of Florida in the US drew their conclusions after tracking the food, fluid and alcohol intake of six male and five female rats over several days in three separate experiments.
They claim rats knew when to draw the line on 'another drink', stopping at what would amount to two or three drinks in most people.
The findings of the study clearly place the responsibility for over-eating or drinking on the individual.
"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," says Neil Rowland, professor of psychology who studies the neural mechanisms of obesity, eating disorders and alcohol abuse.
Obesity is a major risk factor for many chronic and debilitating conditions such as type 2 diabetes, cardiovascular disease and joint problems. But the condition is now reaching epidemic proportions, the world over.
Almost one third of people living in the European Union are overweight and more than one in ten is now obese, according to European Association for the Study of Obesity.
The numbers of children who are overweight is set to rise from 20 per cent to 25 per cent by 2008, say analysts Datamonitor.
In the US an estimated 65 per cent of adults and 16 per cent of children and adolescents are either overweight or obese, according to the Centers for Disease Control and Prevention.
Writing in the current issue of Pharmacology, Biochemistry and Behavior, the UF researchers claim their work supports the idea that people do not consider the nutritional aspects of beer, spirits, mixed drinks and even soft drinks.
"Outside factors are overriding the natural signals that we've eaten enough or have had too much to drink," they say.
"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 analyse more than just one thing."
For the study, UF researchers made alcohol more palatable by adding it to de-carbonated, non-alcoholic beer, enabling the 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. We have to use willpower to control our caloric consumption," he said.
The scientists report that further investigations into 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.