FatMax: definition, training (zone) and exercise test

Whether you like cycling, running or any other endurance exercise: knowing your FatMax zone will enable you to train your fat oxidation and boost your endurance performance. This blog contains everything you need to know about FatMax. From theory to practical application. Let’s dive right into it!


FatMax is the maximum amount of fat that an athlete can “burn” per hour. It is often expressed in energy (kcal) per hour. FatMax is also a training intensity: the intensity at which you burn the highest amount of fat.

The FatMax can differ vastly from one athlete to another. Important factors that together have a huge influence on the FatMax are: VO2max, VLamax and body composition.

When looking at an individual athlete, the fat burning rate (or better: fat oxidation rate) depends on the exercise intensity.

  • At low intensities you will not burn a lot of fat, since you don’t burn that much energy at all.
  • When intensity increases, fat oxidation increases as well. But only up to a point (= FatMax).
  • At very high intensities, you will not burn any fat.

As a result, you get a concave (upward; n-shaped) parabola:

FatMax infographic


In endurance sports like (marathon) running, triathlons, open water swimming and cycling, a high FatMax is associated with a high performance. That is because using fat as a fuel saves carbohydrate stores (glycogen).

Saving carbohydrate stores ensures you don’t run out of glycogen unnecessarily fast. That is a good thing, since once you do run out of glycogen, fatigue will develop quickly. In other words: burning more fat during endurance events delays fatigue.

Watch the video to learn more about fat and carbohydrate combustion:

How to increase fat combustion (FatMax)

We collected the 3 best training tips to increase fat combustion. Two of them will increase fat combustion immediately and one will increase FatMax over time. We’ll dive into training and nutrition.

Get 3 tips on how to increase your fat combustion via our free whitepaper:


Knowing the importance of FatMax and the fact that the maximal fat metabolism is highly individual, leaves us with the question: how can you determine FatMax? The determination of FatMax is done via a FatMax test.

When using the INSCYD software, your have multiple options when it comes to testing. You can do a lactate (field) test, a spirometry (lab) test, a test that only requires power (cycling) or GPS (running), or a combination of the above. All tests will give you an accurate FatMax and FatMax intensity.

Athletes can easily find an INSCYD coach and perform a (remote) FatMax test. Coaches can become an INSCYD coach, test and discover the FatMax of their athletes and create the best FatMax trainingplan. Start now!


After performing an exercise test, the INSCYD software creates your individual fat combustion graph. You now know exactly how much fat you burn at any given exercise intensity. You also know your FatMax (kcal/h) and FatMax intensity (e.g., speed or pace in running and swimming; power in cycling).

Fat & carbohydrate combustion graph
The green line shows the fat combustion rate. The FatMax is 504 kcal/h (y-axis) and occurs at a FatMax intensity of 214 watt (x-axis). The vertical shaded zone is the FatMax zone (+/- 10% of FatMax intensity).

INSCYD also offers you an individual FatMax training zone. This training zones is +/- 10% of the FatMax intensity. Ride/run/swim/exercise in this FatMax zone and you are sure you’ll burn the most fat. Knowing the FatMax zone allows you to train fat combustion more efficiently.

FatMax training zone
FatMax training zone INSCYD


Enough about the theory. It’s time to increase FatMax by training! Here are the three most important rules to follow for increasing fat oxidation rates. The whitepaper discusses both the training aspect as the nutrition aspect. No pseudoscience – just clear physiological facts…steeped in science.

If you coach or lab and you are not sure how to apply FatMax to your training or lab setup? Schedule a free 1:1 consultation with our INSCYD team, available in your own language! We’ll help you get the most out of FatMax for optimal endurance performance. Book your consultation now!