Carbs Are Your Primary Fuel Source — Here's the Science

Let's talk about carbohydrates, because they get such a bad reputation — and it's costing people their performance.

Carbohydrates are your body's preferred and most efficient fuel source for exercise. They're broken down into glucose, stored in your muscles and liver as glycogen, and used to power everything from a heavy lift to a long run. Your brain runs on glucose too. Cutting carbs too low doesn't just hurt your workouts — it affects your energy, focus, and recovery.

How much do you actually need?

For most moderately active people, 3-5g of carbs per kg of bodyweight per day supports training and daily function. Athletes training at higher volumes may need more — up to 6-10g per kg on heavy training days.

Before your workout:

Your muscles store roughly 400-500g of glycogen (more in trained athletes), which is enough fuel for about 60-90 minutes of moderate-to-intense exercise. Eating a carb-containing meal 2-4 hours before training tops off those glycogen stores and ensures you're not running on empty.

The 60-minute rule:

Here's the key point: if your workout lasts under 60-90 minutes, your existing glycogen stores are almost always enough to fuel you through it — assuming you're eating carbs at your regular meals. You don't need extra carbs mid-workout.

But if your session runs longer than that — think longer runs, extended strength sessions, or endurance training — your glycogen stores start running low, and performance drops off if you don't refuel. This is when extra carbs during your workout (think 30-60g per hour) actually matter.

After your workout:

Post-workout, your muscles are primed to replenish glycogen more efficiently than at any other time of day. Pairing carbs with protein within a couple hours of training supports both glycogen replenishment and muscle repair.

The bottom line:

If you're eating carbs at your regular meals throughout the day, you're almost always covered for workouts under 60-90 minutes. It's only when your training goes longer than that — or when you're doing back-to-back sessions — that you need to think about extra carbs specifically timed around your workout.

Carbs aren't the enemy. They're the fuel that makes everything else — your strength, your energy, your recovery — actually work.

Real Food Carb Sources — Quick Reference

~15g carbs (a "starch" serving):