Hello Runner,

Welcome back to your weekly moment of endurance nutrition!

Happy Weekend!
How was your week?

I had a good week... even though I had to say goodbye to the wonderful weather in Galicia and head back to Barcelona.
I’m back to my usual routine now, including workouts, work, and studies.

It was really nice to take a week off with my family and enjoy lots of seafood, fish, artisanal bread, fruit straight from the tree, and so on. I already miss the walks along the seashore with that chilly breeze that only the Atlantic can provide.

Let's talk about excessive protein intake and what happens when runners eat too much protein? Let’s!

These days, the market is flooded with protein products. Everything from bread and yogurt to drinks, ice cream, chocolate, and even protein water is now being sold.

Social media is overflowing with protein-rich recipes and content suggesting that everyone needs to meet or even exceed their daily protein goal.

But does everyone really need to? Who exactly is this “everyone”? What happens to runners who consume too much protein? Let me explain.

Protein is essential for muscle repair, recovery and adaptation. But when it comes to endurance running, more protein is not necessarily better.

One common nutrition mistake is focusing so heavily on protein that carbohydrate, and sometimes fat, fibre and total calories, get pushed aside.

→ For runners, that can mean less fuel, poorer training quality and a drop in performance.

Runners, you have to think of nutrition as supplying different tools:

Protein cannot simply replace carbohydrate.

During running, particularly when intensity increases, your muscles rely heavily on carbohydrate stored as glycogen. If you repeatedly eat too little carbohydrate, you may not adequately replace the glycogen used during training.

You can therefore eat plenty of protein and still be under-fuelled for running.

When you finish a hard run, you need a meal containing substantial carbs to begin restoring your glycogen stores.

If you eat a very large protein-rich meal and relatively little carbohydrate, your body won’t replenish glycogen rapidly.

The protein can provide amino acids for muscle repair, but it doesn't replace carbohydrate's role.

Your body can use amino acids for energy and convert some of them into glucose through a process called gluconeogenesis, but this is not a reason to deliberately replace carbohydrate with protein.

The result can be:

Protein ↑
Carbohydrate ↓
Glycogen restoration ↓
Fuel available for subsequent training ↓
Fatigue and perceived effort ↑
Performance potentially ↓

→ Turning protein into glucose is slow, metabolically costly, and not designed to fuel long or hard sessions.

Gluconeogenesis could be roughly called a backup survival pathway, not a performance strategy. It is not a good thing (in this context) and can have negative side effects if it goes on for too long.

→ Compromised recovery

Recovery requires several things:

glycogen restoration + muscle repair + adequate energy + fluid/electrolytes + micronutrients

Protein is particularly important for muscle repair. Carbohydrate is particularly important for glycogen restoration. You need both.

→ You may unintentionally eat too few calories

High-protein foods can be very filling. If protein replaces substantial amounts of carbs or fat, total energy intake may fall below what your training requires.

That creates a bigger problem (which I already talked about here in the newsletter): low energy availability.

Chronic under-fuelling can affect recovery, immunity, hormones, bone health and injury risk, not just running performance.

→ Fat and fibre can also get squeezed out

A protein-heavy diet can leave less room for foods supplying healthy fats, fibre and micronutrients.

That may mean fewer:

A diet can therefore be very high in protein while still being nutritionally inadequate for a runner.

Over-prioritising protein for extended periods could be an issue.

If you continually replace needed carbs with excessive protein, you may end up with:

less carbohydrate → less glycogen restoration → less available fuel → harder training → poorer training quality → potential performance decline.

And if protein also displaces fat, fibre and total calories, the consequences can extend beyond performance.

Don't let a fixation on protein leave your running under-fuelled.

If you're unsure whether you're eating too much protein and feel like you're not eating right, or if you're wondering how you should eat to have enough energy, let's talk. Just reply to this email, and I'll get in touch with you.

Scientific References

Any questions or something you would like to share? Drop me an email

Wishing you a great weekend and week ahead!

Here’s to health and good runs⚡️

Ana Paula Alonso