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I’m a little late this week. Proof that, yes, I’m a real human with three little kids and no real grasp on summer holiday logistics.

A couple of weeks ago, I was in Châtel on holiday with friends and caught the final meters of Pauline’s ride across the finish line of this year’s Tour de France Femmes. I’ve always liked cycling, but I’ve never given myself the time or space to be into it. It’s always felt slightly out of reach with all of the gear and all of the jargon.

But watching those women push through the finish reminded me how powerful it is to have role models you actually identify with. It also made me wonder about all of the behind-the-scenes work that fuels that kind of stamina—and how little we talk about the nutritional side of performance when it comes to women.

Which is what led me down today’s research rabbit hole: creatine. It’s a supplement that many associate with gym guys and protein shakes, but one that (unsurprisingly) plays a central role in how every cell in our bodies makes energy.

So what does creatine actually do? And why is it finally on the radar for women?

Your Body’s Instant Energy Reserve

Every cell in your body runs on ATP, short for adenosine triphosphate. Think of ATP as your body’s “energy coins.” Every time your muscles contract or your brain fires a signal, you spend some of those coins.

Our bodies don’t store much ATP at once, only a few seconds’ worth. So they’re constantly making more.

Your body has three main ways of making ATP:

1. Aerobic metabolism (oxygen + carbs or fat):

• Speed: Slowest to start, but makes the most ATP.

• How long it lasts: Hours.

• When it’s used: Endurance activities (cycling, walking, daily movement).

• Job: Keeps you going once the demand levels off.

2. Anaerobic glycolysis (glucose without oxygen):

• Speed: Medium — kicks in after a few seconds.

• How long it lasts: About 30-90 seconds.

• When it’s used: Short, intense efforts like a 400-meter run or a steep hill climb.

• Job: Buys time before the long-term system takes over.

3. Phosphocreatine system (creatine):

• Speed: Almost instant (works in fractions of a second).

• How long it lasts: Just a few seconds.

• When it’s used: Quick bursts (sprinting up stairs, carrying all the grocery bags at once, jumping, or focusing hard when you’re exhausted).

• Job: Acts like a backup battery so you don’t run out of ATP before the other systems kick in.

Creatine is the only system that works instantly. Your muscles and brain store creatine in a “charged up” form called phosphocreatine.

When you suddenly need energy—say, you leap up to catch a toddler, or sprint to catch a train—phosphocreatine donates a phosphate to ADP (used-up energy), instantly turning it back to ATP (fresh energy). This reaction happens in milliseconds.

Why Creatine Matters

Without enough creatine, the energy buffer is smaller. Your body still makes ATP, but it has to rely more on slower systems. That means you fatigue more quickly in short, intense efforts.

The brain and reproductive tissues also depend on quick energy. This is why researchers are exploring creatine’s role, not just in muscles, but also in mood, memory, and fertility.

When creatine is low, your body compensates. It leans harder on glycolysis and oxidative systems, but those take longer, produce byproducts like lactate, and can’t prevent the sudden energy crash in the same way.

While creatine isn’t the only way your body makes ATP, it’s the only one that can step in immediately when energy demand spikes.

Most of what we know about creatine comes from studies on men. But that’s starting to change. We’re beginning to find out what it means for energy resilience across women’s lives. 

💬 Do you think women are still overlooked in nutrition and sports research — and how does that affect your trust in health advice? Reply and let me know.