Fuel 101: Protein

Fuel 101: Protein

Why protein matters for recovery

Protein has a bit of a reputation problem in endurance sport. It's the macro that bodybuilders obsess over, and somewhere along the way a lot of cyclists and runners decided it wasn't really their concern. Hit the carbs, get the session done, repeat.

This is a mistake. Protein is what your body uses to rebuild muscle tissue after training, synthesise enzymes and hormones, support immune function and repair the general wear and tear that hard training inflicts. Getting enough of it, and getting it at the right times, is one of the most reliable ways to recover faster and adapt better.

What protein actually does

Protein is made up of amino acids, and there are 20 that matter for human health. Nine of these are essential, meaning your body can't make them and you have to get them from food. The other eleven your body can produce itself.

When you train, particularly when you do any kind of strength or high-intensity work, you create micro-damage in muscle tissue. That damage is intentional — it's the stimulus for adaptation. But your body needs the raw materials to carry out the repair work, and those raw materials are amino acids from dietary protein.

Beyond muscle repair, protein supports the production of haemoglobin (which carries oxygen in your blood), enzymes involved in energy metabolism, and the antibodies that keep your immune system functioning. Under-eating protein consistently impairs all of these things.

How much do you actually need?

The standard recommended daily allowance for protein is 0.8 grams per kilogram of body weight. That figure is designed to prevent deficiency in sedentary adults. It is not a target for someone training regularly.

For endurance athletes, the current evidence points to somewhere between 1.6 and 2.0 grams per kilogram of body weight per day as the useful range. Some research suggests going up to 2.2 grams per kilogram during periods of heavy training or when in a calorie deficit, because the body is more likely to use protein for energy when overall intake is low.

A 70kg athlete at 1.8 grams per kilogram needs around 126 grams of protein per day. Spread across three or four meals, that's roughly 30 to 40 grams per sitting, which is achievable without resorting to protein shakes at every turn.

Timing matters more than most athletes realise

Total daily protein intake is the priority. But when you eat it also makes a meaningful difference.

After a training session, muscle protein synthesis (your body's repair process) is elevated for several hours. Consuming 25 to 40 grams of protein within a couple of hours of finishing a session takes advantage of this window. It doesn't need to be a shake. A proper meal with a good protein source works fine.

Research consistently shows that spreading protein evenly across meals produces better results than eating most of it in one sitting. Your body can only put so much to use at once. Three or four protein-containing meals across the day is more effective than one large evening meal, regardless of the daily total.

One amino acid in particular, leucine, is especially important as a trigger for muscle protein synthesis. You need around 2 to 3 grams of leucine per meal to reliably stimulate the process. Chicken breast, eggs, dairy, fish and red meat all contain this in good quantities. For plant-based athletes, soy is one of the few plant proteins with a comparable leucine content; others often need to be combined to hit the threshold.

Complete and incomplete proteins

Animal proteins from meat, fish, eggs and dairy are complete proteins. They contain all nine essential amino acids in amounts your body can use effectively. Plant proteins are mostly incomplete, meaning they're low in or missing one or more essential amino acids.

This doesn't make plant-based eating difficult for athletes. It just means paying a little more attention to variety. Combining different plant protein sources across the day covers the full amino acid profile without needing to engineer every meal. Rice and legumes, oats with a handful of nuts, hummus with wholegrains — these combinations have been feeding people well for centuries.

Protein on rest days

Some athletes reduce their protein intake on rest days, reasoning that they're not training and therefore don't need as much. The opposite is often closer to the truth.

Muscle repair and adaptation continue for 24 to 48 hours after a hard session. The day after a long ride or a tough interval session is often when your body is doing the most rebuilding work. Keeping protein intake consistent on rest days supports that process.

You might eat fewer carbohydrates on a rest day. Protein should stay roughly the same.

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