Intermittent fasting and sports: does 16:8 work for athletes? (2026)

Intermittent fasting (IF) has grown from a hype into a fixed eating pattern for hundreds of thousands of people in the Netherlands. But what if you train seriously? Will you lose muscle? Is it better to train on an empty stomach, or actually not? In this article we discuss what the 16:8 protocol actually means for athletes, who it works for and when you’d be better off looking at a different eating pattern.

What is 16:8 and how does it work?

The 16:8 protocol is the most popular form of intermittent fasting. You fast for 16 hours a day (water, coffee and tea are allowed) and eat all your calories within an 8-hour window. A typical Dutch example: last meal at 20:00, skip breakfast, and start eating again from 12:00.

Important: IF is not a diet in the sense of what you eat, but an eating pattern in time. Whether you’re cutting hard or sitting at maintenance, your total calorie and protein intake remain the decisive factors. Read our guide on calculating calorie needs in 2026 to first set your daily total before you start with a window.

Training in a fasted state: fact and fiction

A large part of the IF crowd trains fasted, hoping to burn more fat. What does the research say?

What’s true

Slightly more fat oxidation during low intensity (walking, easy cycling) in a fasted state
Possibly lower insulin response later in the day
Practical benefit: no time lost to breakfast in a busy morning

What’s NOT true

More fat loss in the long run: studies summarised by Kenniscentrum Sport show that IF and regular calorie restriction work equally well for fat loss, provided calorie intake is identical.
Better strength training performance when fasted: here you actually run the risk of hitting fewer reps or recovering worse.

When fasted training does make sense

Low-intensity cardio (zone 2 walking, cycling) of 30 to 45 minutes can be done fasted without issues. For strength training or HIIT, a small pre-workout (a banana, some low-fat quark) is almost always better — even within an IF schedule. Plan your strength training inside your eating window.

Muscle preservation during intermittent fasting

The biggest concern athletes have: will my muscle stay intact if I fast for 16 hours?

The answer: yes, provided you meet two conditions:

Enough protein within your 8-hour window: aim for 1.6 to 2.2 grams of protein per kilo of body weight, spread across 3 to 4 meals.
Strong training stimulus: keep training heavy, with progressive overload.

For an athlete of 75 kilos that means 120 to 165 grams of protein, spread across for example 3 main meals of 35 to 50 grams. A lunch with 200 g chicken fillet, a dinner with 200 g salmon and an evening snack of 250 g quark already covers this comfortably. According to the Voedingscentrum, most people in the Netherlands already get a sizeable share of their protein in the evening hours — which fits well with a 12:00 to 20:00 window.

If you train intensively and want to build serious muscle, IF can work, but it isn’t optimal. For maximum muscle growth, spreading protein across 4 to 5 meals instead of 3 is slightly more effective.

Who does IF work for, and who not?

IF fits well with:

People who don’t feel hungry in the morning anyway
Those who want to lose weight and struggle with portion control across the whole day
Busy working parents who don’t miss breakfast
Recreational athletes (2-3x per week) who mainly want to lose weight
People who want to tie their exercise frequency to a simple eating pattern

IF fits less well with:

Women with an irregular menstrual cycle (prolonged fasting can disrupt it further)
Athletes who train hard every morning
People with a history of eating problems
Competitive athletes who need every percent of performance
People with diabetes or other metabolic conditions (consult your doctor first)

For women specifically: the RIVM points to the importance of sufficient energy intake around the menstrual cycle. If you feel tired, irritable or notice changes to your cycle, that’s a signal to widen your window or stop IF. Our guide on daily calories for women helps you establish a safe minimum.

Dutch practical example: skip breakfast or dinner?

In the Netherlands we see two dominant variants:

Variant A: skip breakfast (12:00–20:00 window)

12:00: lunch with 4 slices of bread, chicken fillet, egg, salad
15:30: snack: 250 g quark + handful of nuts
19:00: warm dinner with 200 g meat or fish, vegetables, carbs
Fast from 20:00 to 12:00

Benefit: fits well with office work and family dinners.

Variant B: early dinner (10:00–18:00 window)

10:00: breakfast with 4 eggs, bread, quark
13:30: lunch with salad and fish
17:30: early dinner
Fast from 18:00 to 10:00

Benefit: better sleep quality, less reflux, aligns with the natural circadian rhythm.

Which one you pick depends on your work schedule and social life. Try one variant for 4 to 6 weeks before you judge whether it works.

Combining IF with other goals

Losing weight

IF is a handy tool for getting into a calorie deficit — not because it miraculously boosts fat burning, but because a shorter eating window often automatically leads to fewer calories. Combine it with strength training to preserve muscle. For specific age groups read losing weight after 50 for an adjusted plan.

Getting leaner

Want to lower your body fat percentage and see more visible muscle? Combine IF with strength training 3 to 4 times per week, enough protein and a light calorie deficit of 300 to 500 kcal. For athletes over 40 we recommend getting lean after 40 as a base plan.

Fitness and heart

Light fasted cardio is fine and can help with fat burning. Do keep an eye on your heart rate. If you’re wondering what a normal resting heart rate is, our guide on a resting heart rate of 40 gives you context.

Quick results

If you want to see visible results in a month, IF can provide a framework — but the real wins come from consistency in training and calories. Our guide on getting fit in 1 month lays out the steps.

Risks and signs to stop

Stop or adjust your window if you experience:

Persistent fatigue and concentration problems
Worse training performance over multiple weeks
Sleep problems or dizziness
Changes in your menstrual cycle
Thoughts that revolve obsessively around food

IF should make your life simpler, not more complicated. If it isn’t working after 6 weeks, it simply doesn’t suit your body or lifestyle — and that’s fine.

Veelgestelde vragen

Will I lose muscle if I fast for 16 hours?

Not if you get enough protein (1.6 to 2.2 g per kg) and calories within your 8-hour eating window and keep training seriously. For muscle preservation the window matters less than your total daily intake.

Can I drink coffee or tea during the fast?

Yes, black coffee, tea and water don't break your fast. Don't add milk, sugar or broth — that activates your digestion and technically breaks your fasting period.

Can I do strength training fasted on IF?

You can, but it isn't optimal. You often perform worse and recover more slowly. Preferably plan your strength training inside your eating window or have a small pre-workout snack such as a banana or some quark.

Does IF work better for men or women?

Research suggests men can fast for longer somewhat more easily without hormonal consequences. Women, especially around their cycle or in menopause, need to watch for signals like fatigue or cycle changes. A shorter fasting period of 12 to 14 hours can already be enough.