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Critique 160: Do the calories in alcoholic beverages lead to increased obesity? — 23 March 2015

Among people who consume alcohol, it would be assumed that the excess calories provided by the alcohol would add to their risk of obesity; however, current data suggest that the association may be more complex. It is unclear to what extent people who consume alcohol may modify other aspects of their diets, either decreasing or increasing other sources of calories. Further, alcohol is metabolized differently from other foods, which suggests that its calories may not be as readily available as those from fat, carbohydrate, and protein to increase obesity. The present paper provides an update on scientific data on the association between alcohol consumption and obesity. The overall conclusions of the authors are that light-to-moderate drinking does not increase the risk of obesity, while heavier drinking (or even moderate drinking among obese subjects) may lead to weight gain.

Forum reviewers appreciated the excellent summary of scientific reports on this topic, and thought that the authors gave a sound and balanced update on the topic. However, mechanisms why numerous prospective epidemiologic studies show that moderate drinking does not increase the risk of obesity are unclear. Given that alcohol contains calories, and if drinking alcohol does not displace the intake of other foods, it would be assumed that such calories would increase the risk of obesity unless there are particular metabolic differences between alcohol calories and those from protein, fat, and carbohydrate.

Potential mechanisms suggested have included a decreased utilization of calories from alcohol due to what is known as ‘Non-exercise Activity Thermogenesis’ (NEAT), in which the metabolism of alcohol may create more heat than fat. Also, the Forum discussion included comments that alcohol could bring into play effects on insulin, glucose, and fat mobilization (however, in the laboratory, such mechanisms tend to increase, rather than decrease, body fat). Also, a reasonable interpretation of the fat tissue decrease related to ‘moderate’ ethanol intake seen in many studies could be an associated decrease in the intake of carbohydrates. One glass of wine substituting for approximately 50 g of glucose could be a reasonable mechanism for shifting the metabolism from lipogenesis to oxidation of lipids. Genetic factors undoubtedly play a role in the effects among individuals.

In summary, this update on the association of alcohol consumption and obesity concludes that most well-done prospective studies show that moderate drinkers do not have an increase in obesity, and in some studies there is even a slight decrease in weight. One possibility is that, especially for wine with meals, satiety may occur earlier and result in less intake of food. However, precise mechanisms for a lack of increase in weight are not known, and the effect could still result from drinkers compensating for their drinks by taking in fewer calories from other sources and perhaps also by being a little more physically active.

Reference: Traversy G, Chaput JP. Alcohol Consumption and Obesity: An Update. Curr Obes Rep 2015;4:122–130. DOI 10.1007/s13679-014-0129-4

For the full critique of this paper by members of the International Scientific Forum on Alcohol Research, please click here.

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