Running on an empty stomach: what you need to know

Running on an empty stomach in the morning, before breakfast, is a common practice. Used correctly, it has benefits; used poorly, it just tires you out for nothing. Here's how to do it right.

The real benefit

On an empty stomach, your glycogen reserves are low, which pushes your body to better use fat as fuel. Repeated over time, this can improve your metabolic efficiency in endurance — useful for long distances.

The golden rule: keep it easy

Fasting is ONLY suitable for easy sessions that aren't too long (endurance, 30 to 60 min max at first). Without available fuel, you won't be able to do quality work: interval training or intense sessions on an empty stomach = counterproductive and risky. Save the intensity for fed sessions. That's consistent with 80/20.

The risks to know about

• Hypoglycemia: dizziness, wobbly legs — stop if it happens.
• Poor quality sessions if you push too hard.
• Not ideal if you're a beginner or prone to hunger pangs.

How to do it right

Start short (30 min), hydrate before (water), stay at a comfortable breathing pace, and eat well after the session to recharge. No need to overdo it: 1 to 2 easy fasted runs per week is plenty.

For whom?

Better suited to experienced runners preparing for long distances. If you're starting out, focus on consistency first — see getting started with running.

Integrated smartly into your plan

Sports Coach AI places easy sessions (ideal for fasting) and quality sessions (to be done fed) at the right time of your week, according to your load and recovery.