How bad is a post-gym pint?

A beer after exercise isn’t the end of the world, but too much too often and all your hard work comes undone, says Kamal Patel, director of examine.com

Nothing quite quenches a thirst like a pint of ice-cold beer, especially after a big-game win or a particular long and sweaty workout. And because lager contains both energy-replacing carbohydrates and hydration-helping electrolytes many a wishful drinker has been quick to toast a hard session with a couple of cold ones. But just how damaging is booze after exercise if you’re trying to add muscle or burn away fat? And could a beer really replace an a isotonic sports drink or a protein shake to aid recovery?

There’s good news and bad news. Studies have looked at how the amount of alcohol consumed affects the rate at which proteins are synthesised by the liver. The faster the rate, the quicker proteins can be used for the primary role of tissue and cell repair and recovery.

One study, published in the Journal of Nutrition, found that protein synthesis was not suppressed at all after the consumption of 28g of alcohol. In the UK one alcoholic unit is defined as 8g of pure alcohol, so that’s the equivalent of slightly more than one pint of 5% lager. So sticking to just one jar seems to not negatively impact how quickly your body builds muscle.

However, research published in the Journal of Clinical Investigation found that protein synthesis rates were suppressed by 24% after 71g of alcohol, which is the equivalent of almost three pints of lager. My guess though is that if you’ve necked three pints in quick succession the speed at which your biceps are growing is pretty far from the forefront of your mind.

Know your limit
Muscle protein synthesis, or the process by which the protein you consume through your diet is converted into muscle tissue, is also affected by alcohol consumption, and animal studies have given us a good understanding of exactly how much an individual can drink before lean muscle mass growth is affected.

The rate of muscle protein synthesis in rats was suppressed after they received injections of 1.5g of alcohol per kilogram of bodyweight, according to research published in the Journal of Alcohol and Alcoholism, which also gives a whole new meaning to the phrase ‘rat-arsed’.

To put that into context this dose is equivalent to approximately 112g grams of alcohol for a 75kg person, which is just shy of four and a half pints. Significantly, the rate was affected even after the rats were given 25g of protein first, suggesting that even a post-workout protein shake won’t insure your gains if you plan on sinking a few jars later on.

Therefore, more than a couple of pints will suppress muscle protein synthesis, which will impair workout recovery and muscle growth.

The T factor
There is one other consideration you need to bear in mind when thinking about drinking after a workout, and that’s the impact of booze of the male sex hormone testosterone. The higher your levels of circulating testosterone the easier your body will build muscle, burn fat and send your sex drive through the roof.

Low doses of alcohol – around 0.5g per kilo of bodyweight or 1.5 pints – can increase circulating testosterone levels by 17%, according to the journal Alcoholism: Clinical and Experimental Research. However, another study published in the same journal found that increasing that dose to 1.5g per kilo – that’s 4.5 pints – and your levels will fall.

However, that doesn’t mean you can drink less but more often because subsequent research found that having 30g to 40g of alcohol, which is around two pints, every day for three weeks had the same detrimental effect on free testosterone.
So while a pint can boost your levels, drinking more than two pints too often will see your levels of testosterone plummet.

One for the road
The research is pretty convincing: a pint after training has a negligible effect on both muscle protein synthesis and testosterone levels. So if a cold beer is your favourite way to unwind and relax after a tough day and even tougher workout then go for it. Just make sure that a quick pint doesn’t turn into an all-night session because the evidence is clear that it will undo all of your hard work.

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