Can alcohol cause weight gain? What you need to know about alcohol metabolism

Before moving on to today’s topic please read my disclaimer:

• I do not support, condone, or encourage the consumption of alcoholic beverages.
• I am not liable for the use of this information by minors or unlawful use or consumption of alcohol in any way.
• Information about alcohol pathways and guidelines is provided with the intention to educate adults on its potential effects on weight management.

Human study results on the relationship between alcohol consumption weight gain has not been very consistent. The reason is that other factors like age, sex and overall dietary habits have an important role as well. In fact, it could be hard to know exactly how much alcohol contributes to weight gain comparing to other factors^, .

Last year, a meta-analysis on 22 studies showed that when people drink alcohol, they usually do not reduce their food intake. In some studies food intake actually increased. These results are in agreement with older study results .

Ethanol contains 7 kcal/gram. Since total daily energy intake increases, alcohol consumption could lead to weight gain.

Alcohol dose seems to have a role in potential weight gain.

• The same meta-analysis showed that both low and high alcohol drinks resulted to higher energy intake. High alcohol drinks resulted to a more noticeable increase in energy intake.
• This result is in agreement with the Health Professionals Follow-up Study where the relationship between the increase of alcohol drinks per day and (moderate weight) gain over for years was linear .
• The Health Survey for England and the Scottish Health Survey showed that regardless of sex, high alcohol consumption in one session was significantly associated with being overweight or obese .

UK guidelines for alcohol consumers

The Department of Health recommends for regular alcohol consumers ^, :

• Not to drink more than 14 alcohol units (AU) per week.
• If you are regularly drinking close to 14 AU/week, spread your drinks over three days or more
• Try to have several alcohol free days

What is an alcohol unit and how can we calculate it ?

• 1 unit= 10g or 8 ml of pure alcohol
• Alcohol by volume (ABV) = the quantity of pure alcohol as a percentage of the total volume of the drink

Click here to use the Alcohol Change UK’s unit calculator for your drinks!

Alcohol metabolic pathway: Why could it contribute to weight gain?

What makes ethanol different than other macronutrients (protein, fat and carbohydrates) is that the body cannot store it, its metabolites (substances formed occur when its metabolized) are toxic and hormones do not have an important role in how fast it is going to be eliminated from the body^. . For these resasons:

The body prioritizes using the energy derived from alcohol, as a way to eliminate it as fast as possible. Energy from other nutrients is not used while alcohol is metabolized. As a result, a bigger part of the energy from actual food will be stored as fat

Having alcohol could limit protein oxidation by 40% and fat oxidation by 75% .

How does this happen?

1. Ethanol is oxidized to a toxic substance called acetaldehyde. During this reaction NAD+ (Nicotinamide adenine dinucleotide) turns into NADH.
2. Acetataldheyde then turns into acetate. Again, NAD+ turns into NADH. Acetate is then used for energy production.

Because of the increase of NADH and reduction of NAD+, metabolic processes of other nutrients (including glycolysis, glyconeogenesis and fatty acid oxidation) are inhibited .

There are possible mechanisms that cause alcohol to increase appetite:

• Ethanol could bypass satiety chemimal signals which are produced in short time after eating .
• It could bind to GABAa receptors and affect satiety signals
• It could decrease serotonin production and serotonin normally reduces appetite ^.

What should we remember?

• Alcohol is toxic. The more you can limit it, the better.
• If you are a regular alcohol consumer, it would be better for healthy to try and stick to the guidelines!
• In terms of weight management, total energy intake is still more important for weight gain or weight loss. However, alcohol intake could contribute to increasing food intake and it could disrupt the metabolism of other nutrients. Consequently:

Reducing alcohol intake as much as you can could help you during your fitness journey not only because of its energy content, but also because of its possible effects on metabolism and central nervous system.

Finally, a few tips for alcohol intake if you are trying to lose weight:

• When you go outside, try not to order more than one drink. You could try ordering one alcoholic drink and one low-energy non- alcoholic drink instead!
• Try to avoid coctails! They can be really high in energy and added sugar. A coctail could have the calories of a whole meal!
• Avoid sweet alcoholic drinks, like liquor and sweet wine.
• A glass of dry wine/ champagne are better options.
• Keep in mind that alcoholic drinks with high ABV (eg. vodka) will have more calories as well. For example, 355 ml of beer contain 153 kcal, while only 71 ml of vodka contain 153 kcal.

Thank you so much for reading. Alcohol intake is a sensitive topic with many possible health-related implications. If you have more specific questions or you feel like you have issues with alcohol consumption, please consult with your doctor!

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