Do alcohol calories count for weight gain/loss?

Question

For normal food, every extra 3500 Calories consumed tend to lead to 1 lb weight gain. However, nutrition tables are created using calorimetry, that is by burning food down to CO2 and H2O, rather than in vitro experiments. Some foods are hard to digest, and will cause less weight gain. Others may be seen as toxins by the body and not digested like normal food. If they are excreted as something with higher energy than CO2 and H2O, their energy is wasted.

Do alcohol calories count for weight gain/loss? More generally, how much do they count? Does 1 calorie from alcohol count more or less for weight gain/loss than 0.5 calories from carbs? Is this different for someone sipping wine for dinner and someone binge-drinking once a week?

Answer 1

Harvard.edu seems to say they count as much as the calories in fat:

Nutrition-wise, alcohol is similar to dietary fat. Like fat, alcohol is mostly metabolized in the liver. At seven calories per gram, alcohol’s energy content is also closer to that of fat, which has nine calories per gram, than to that of carbohydrates or protein, each of which contains four calories per gram.

Answer 2

MWB's answer addressed the first question, indicating that alcohol calories behave similar to fat.

Regarding your second question comparing moderate daily intake to binge drinking, the answer seems to be complex. This study indicates correlation, but not causation:

In general, recent prospective studies show that light-to-moderate alcohol intake is not associated with adiposity gain while heavy drinking is more consistently related to weight gain. ... However, many factors can explain the conflicting findings and a better characterization of individuals more likely to gain weight as a result of alcohol consumption is needed. In particular, individuals who frequently drink moderate amounts of alcohol may enjoy a healthier lifestyle in general that may protect them from weight gain.

Another study referenced by the one quoted above gives a bit more insight, noting that while the calories may be the same, the interaction with and/or separation from food may be an important factor, but is still secondary to other factors:

Current research clearly shows that energy consumed as alcohol is additive to that from other dietary sources, leading to short-term passive over-consumption of energy when alcohol is consumed. Indeed, alcohol consumed before or with meals tends to increase food intake, probably through enhancing the short-term rewarding effects of food. However, while these data might suggest that alcohol is a risk factor for obesity, epidemiological data suggests that moderate alcohol intake may protect against obesity, particularly in women. In contrast, higher intakes of alcohol in the absence of alcohol dependence may increase the risk of obesity, as may binge-drinking, however these effects may be secondary to personality and habitual beverage preferences.

So in sum... the chemical energy is the same. But timing of the caloric intake does have some relevance and multiple impacts.

Answer 3

I found this paper (PDF) called "Alcohol Consumption and Obesity: An Update".

It reviews a number of experiments where scientists gave people alcohol and observed changes in their weight after a few weeks. Their summary:

Overall, the available experimental evidence reviewed in this article suggests that moderate intake of alcohol does not lead to weight gain. The systematic review by Bendsen et al. [3•]suggests that this trend is less likely in experimental studies examining beer consumption exclusively. Also, the intervention periods in the aforementioned studies ranged from 4–10 weeks,and therefore may not have been long enough to identify the slight changes in weight that can accumulate over time to result in overweight or obesity. A modest increase in weight of one kilogram over a 10 week period seems insignificant but over five years this could result in up to 26 kg of weight gain if no compensation takes place. To our knowledge, there does not appear to be any experimental evidence specifically testing the effects of heavy/binge drinking, or of drinking spirits or a combination of alcohol sources on weight gain/obesity.

However, this is generally mixing three effects:

• alcohol's effect on food consumption (changes in hunger)
• the energy being absorbed from alcohol itself
• the effect of alcohol on how the energy is absorbed from other food (some say that since the body prioritizes digesting alcohol, it's not digesting other food as efficiently)

If we look at the description of one of the studies (above this summary):

Fletchner-Mors et al. [53]found that replacing 10% of total daily energy intake during a weight-loss intervention with either grape juice or white wine resulted in similar weight loss, with the white wine group showing a slightly higher (although not statistically significant) weight loss. In this case both diets were isoenergetic so this is not a surprising result, as the thermic effect of food was likely higher for white wine than grape juice[53,54].

(emphasis added)

It basically says that (when all calories were counted), the effect of wine on weight gain/loss was essentially the same as that of grape juice with the same amount of calories.