Intermittent fasting and strength training: can you build muscle while fasted?

Yes, it is possible. Muscle is built through a sufficient training stimulus and enough protein and energy over time. Training in the morning without eating does not stop this process, especially if you eat properly after the session.

However, some people feel weaker, dizzier or more irritable when fasted, and their heavy sessions suffer. In that case performance drops, and so does the stimulus. The right choice is the one that lets you train hard and consistently, fasted or not.

The available trials are rather small and short. They suggest that with strength training and enough protein, a 16/8 pattern generally allows you to keep lean mass, sometimes with a slightly smaller gain than a conventional eating pattern in trained people. Results are not uniform.

Intermittent fasting is above all a framework that helps some people control their intake. It has no special power to burn fat: the overall calorie balance decides. If you want maximum muscle gain, a window that is too short makes it harder to reach your calories and protein.

For muscle gain, a range often cited is 1.6 to 2.2 g of protein per kilo of body weight per day. For a 75 kg person, that is roughly 120 to 165 g. This range applies with or without fasting.

In an 8-hour window, aim for 2 to 4 meals, with about 0.3 to 0.4 g of protein per kilo in each. Favor eggs, fish, poultry, turkey, dairy, legumes and tofu. A snack of yogurt or quark can fill the gap if the total is hard to reach.

If you train during your eating window, a meal with carbs and protein 2 to 3 hours before, and another within the hours after, works very well. If you train fasted, try to have your first meal shortly after the session, ideally within one to two hours.

If your session falls at the end of the fasting period, the simplest option is to place it just before you open your window. That way you eat soon after. Avoid putting your heaviest session of the week when you are most tired, and note how you feel so you can adjust.

When fasted, the body uses proportionally more fat during exercise. But studies over several weeks do not show clearly greater fat loss compared with cardio done after a meal, when total calorie intake is the same. The balance over the day and the week remains the dominant factor.

Fasted cardio can suit a brisk walk or an easy jog of 20 to 40 minutes, if you feel good. For intense or long sessions, eating beforehand is often more comfortable. Drink water and stop if you feel dizzy or nauseous.

A short fast of 12 to 16 hours does not cause significant muscle loss in a healthy person who eats enough over the day. The risk rises with a large calorie deficit, too little protein, little sleep or no strength training.

To protect your muscle: keep two to three strength sessions a week, a moderate calorie deficit if you want to lose weight, and enough protein. Track your progress: if your loads stall or fall for a long time, your plan is probably too restrictive.

For many practitioners, the goal during Ramadan is to maintain their level, not to break records. Respect your fast and listen to your body. Common slots: a light or moderate session about 1 to 2 hours after iftar, or sometimes a short session before iftar with a reduced load. Avoid very long or very intense sessions at the end of a fasting day.

You can, for example, reduce load and volume if you feel drained, keep 2 to 3 sessions of 30 to 45 minutes and focus on the big movements. If you still train while fasting, a short technical session is preferable, since you cannot drink during the effort.

At iftar, start with water and dates, then have a balanced meal. Spread your water between iftar and suhoor, often 1.5 to 2.5 liters depending on the heat, and favor a suhoor rich in protein, fiber and slow carbs. Sleep enough. If you feel unwell, stop and break your fast if necessary. People who are ill or on treatment should ask their doctor: Islam provides exemptions for health reasons.

Avoid fasting or ask for medical advice if you are pregnant or breastfeeding, if you have diabetes or take medication that changes blood sugar, if you have a history of eating disorders, or if you are a minor still growing. Frail elderly people or very thin people should also be careful.

Warning signs to stop the session: dizziness, blurred vision, nausea, palpitations, cold sweats, intense headache. In that case, sit down, drink and eat if needed. A plan that obsesses you or makes you feel guilty is not a good plan.

Muscle depends first on training, total protein (1.6 to 2.2 g/kg), enough energy and sleep. 16/8 is compatible with strength training if the window lets you cover these needs. Fasted cardio is not superior for fat loss.

During Ramadan, aim for maintenance: short sessions after iftar, reduced loads, spread-out hydration, good sleep. Listen to your body, respect your health and ask your doctor when needed.

GymProgress helps you check it: you log sets, weights, reps and RPE, you see your records and your volume per muscle, you track your weight with the weekly weigh-in and you can turn on a water reminder. The app is free, on Android and on the web, in French, English and Arabic.