Protein timing on training days

Fasting and building muscle aren't at odds — but on training days, when your protein lands starts to matter. Here's how to line them up.

The Kairo Guide · 4 min read

Total daily protein is the biggest driver of keeping (and building) muscle. Timing is the smaller, second lever — but on days you train, it's worth pulling. The goal is simple: make sure a solid dose of protein lands in the hours around your workout.

Line up training with your window

• Train near the start of your eating window where you can, so your first meal doubles as your post-workout meal.
• If you train fasted (before your window), keep the session moderate and break your fast with protein soon after.
• Put your biggest, most protein-rich meal in the 1–2 hours after training.

How much protein?

A common, practical target is roughly 0.7–1 gram of protein per pound of body weight per day, spread across your meals. In a tight fasting window that means being deliberate: anchor every meal with a real protein source and consider a protein-led snack if your window allows.

Rest days need less

On rest days you simply need less fuel. Keep protein high to protect muscle, lean on vegetables, and it's fine to shorten your window a little if you're not as hungry.

General information only, not medical advice. Consult a healthcare professional before starting any fasting or training routine, especially if you are pregnant, under 18, have a medical condition, or a history of disordered eating.