Alcohol Consumption and Performance

Alcohol and Marathon Training: The Good, the Bad, and the Bubbly

In the weeks leading up to a marathon (or half marathon), runners tend to get very focused on nutrition, mileage, and kit choices. 

But one thing that often slips under the radar is alcohol. Whether it’s a pint at the pub or a glass of wine with dinner, many runners wonder - does it really matter? 

The short answer is yes—BUT with some nuance. Read on.....

The Downsides: Why Alcohol and Marathons Don’t Mix Well

Alcohol is a diuretic, meaning it encourages the kidneys to produce more urine. That’s not ideal when, as the hydration research reminds us, even a small fluid deficit—just 2% of body mass—can impair performance, mood, and cognition. In training / racing, that can translate to heavier legs, higher heart rate, and feeling more fatigued than you should.

Alcohol also competes with water for absorption and disrupts electrolyte balance. Sodium and potassium are crucial for holding on to body water, yet alcohol accelerates their loss, setting the stage for cramps and dehydration during long runs.

Beyond hydration, alcohol affects nutrient absorption. It interferes with how your body takes in vitamins (especially B vitamins) and minerals that support recovery. Pair that with its impact on sleep quality—fragmented, less restorative rest—and you’ve got a recipe for slower recovery, higher injury risk, and diminished energy reserves.

Finally, alcohol is calorie-dense (seven calories per gram) but nutrient-poor. That late-night beer isn’t replacing glycogen stores—it’s simply adding "empty calories."

The Upsides - Don’t Panic About One Drink

That said, it’s not all doom and gloom. 

A single glass of wine or the occasional beer won’t undo your months of training. In fact, for some runners, a small drink can be a pleasant way to relax, take the edge off pre-race nerves, or enjoy a social evening without feeling like a monk in taper week.

Moderation is the key word here. 

A drink with dinner a couple of times a week is unlikely to harm your hydration status if you’re otherwise disciplined about fluid intake. After all, your body’s fluid balance is a dynamic process—losses through sweat, urine, and breathing are constant, and it’s your day-to-day habits that really count.

Striking the Right Balance

If you do choose to drink in the lead-up to your marathon, a few simple habits can make all the difference:

• Hydrate alongside alcohol - For every alcoholic drink, match it with a glass of water to protect hydration and support recovery.
• Choose lighter options - Beer and wine are usually better tolerated than spirits, which are more dehydrating and calorie-dense.
• Avoid big sessions - Heavy drinking within two weeks of the race can leave you depleted, compromise sleep, and risk arriving at the start line below your best.
• Prioritise rest days - If you’re going to have a drink, time it for a lighter training day rather than after your final long run.

Conclusion.....

Don't feel guilty if you'd like to enjoy a glass of wine or a pint in moderation,

BUT  keep water as your best friend in the weeks leading up to race day. Come marathon morning, you’ll be glad you did.