Diet & Fatigue

An apple a day keeps the doctor away, but what about a beer a day? Or for that matter, a glass of wine or even a shot of hard liquor?

It’s well-established that drinking too much, even occasionally, is bad for you, but there’s often uncertainty regarding how moderate drinking affects your energy levels for weeks to come.

According to Dr. Sam Zakhari from, there are some negatives, and some positives, so decisions about whether to drink really depend on people’s individual situations.

But first, establishing what “moderate drinking” means is key for anyone looking for health benefits associated with alcohol, Zakhari said.

For men, moderation means no more than two drinks a day, while for women, moderation means no more than one drink a day. Zakhari emphasized that drinking seven drinks in one day, and not drinking the rest of the week, will have dramatically worse effects on health, even though it averages to the same levels of consumption.

Even though drinking at moderate levels won’t adversely affect your health, as soon as people start drinking more than the recommended amounts, benefits diminish quickly, and a sharp lack of energy arises.

Overall, alcohol is detrimental to performance because of how it affects the brain for many days after consumption. It does this in two main ways.

Firstly, because alcohol is a diuretic, drinking too much can lead to dehydration because the alcohol makes your kidney produce more urine. Working after drinking alcohol can make this dehydration worse because you sweat as your body temperature rises. You need to be hydrated when you exercise to maintain the flow of blood through your body, which is essential for circulating oxygen and nutrients to your muscles.

Secondly, alcohol interferes with the way your body makes energy. When you’re metabolising, or breaking down alcohol, the liver can’t produce as much glucose, which means you have low levels of blood sugar. Work requires high levels of sugar to give you energy. If your liver isn’t producing enough glucose, your performance will be adversely affected. “If your body is forced to run from your supplies of fat rather than blood sugar, you will be slower and have less energy and won’t be able to exercise as intensely,” says Zakhari. As a result, your energy, coordination, dexterity, concentration and reactions could be adversely affected too.

Both effects are immediate which is why it’s not advised to exercise or compete in sport soon after drinking alcohol.