Which macronutrient matters most for endurance performance in IB SEHS?

In IB SEHS, carbohydrates usually sit at the center of endurance discussions because they support moderate to high-intensity exercise where energy demand is high. The important nuance is that endurance is not always “low intensity for a long time” in real sport. Many endurance events include surges, hills, and tactical changes that rely heavily on carbohydrate availability. That is why glycogen depletion is commonly linked to fatigue and performance decline. Fats still contribute significantly during prolonged exercise, especially at lower intensities, but they cannot replace carbohydrates when intensity increases. A strong exam answer explains both fuels and then justifies why carbohydrates often decide the final outcome.

Why are proteins not considered a primary energy source in IB SEHS?

In IB SEHS, proteins are mainly described as structural and functional building blocks rather than a first-choice fuel. Their key roles relate to tissue growth, repair, and adaptation after training, not powering high-output exercise. While protein can contribute to energy in certain situations, it is not efficient or ideal compared with carbohydrates and fats. Markers want you to show that you understand this hierarchy rather than repeating a simple slogan. The easiest way to show sophistication is to state that protein is not the main fuel during exercise, but it becomes essential in recovery and long-term training progress. That framing also helps you avoid oversimplification.

How do IB SEHS exams usually test carbohydrates, fats, and proteins?

IB SEHS nutrition questions often ask you to compare macronutrients, apply them to a scenario, or link them to intensity, duration, fatigue, and recovery. You may be given a sport context (for example, steady cycling vs repeated sprints) and asked to explain which fuels dominate and why. Examiners reward correct terminology such as glycogen, ATP, low vs high intensity, and recovery/adaptation. They also reward balance: explaining that the body uses a mix of fuels, with proportions shifting as intensity and duration change. The fastest way to improve is to practise timed responses and then tighten your wording using model feedback. RevisionDojo’s Questionbank, Flashcards, and AI Chat make that loop much quicker than rereading notes.

This site uses cookie tracking technologies. Learn more in our Cookie Policy.

IB SEHS: Proteins, Fats, and Carbohydrates Explained

IB SEHS

RevisionDojo Team

•1/7/2026•6 min read

If you have ever stared at an exam question about nutrition and thought, “I know what carbs are… but what does the marker want?”, you are not alone. In IB SEHS, macronutrients are not just food categories. They are a story about timing, intensity, and why performance changes when fuel runs low. Once you learn to tell that story clearly, your answers become calmer, sharper, and more convincing.

IB SEHS: picking a snack like it's Paper 2

Quick IB SEHS checklist for macronutrients

Before you write anything in IB SEHS, run this quick check:

Name the macronutrient (carbohydrates, fats, proteins)
Link it to exercise intensity (low vs high)
Link it to duration (short vs prolonged)
Mention the key mechanism (glycogen, slow oxidation, tissue repair)
Finish with an outcome (fatigue prevention, endurance support, recovery)

For syllabus-aligned practice, start with the IB SEHS hub: IB Sports, exercise and health science Resources.

Carbohydrates in IB SEHS: the fast fuel for intensity

Carbohydrates are the body’s preferred fuel when intensity rises. In IB SEHS, the key phrase to remember is that carbohydrates are stored as glycogen in muscles and the liver, then broken down to support ATP production quickly.

That “quickly” is the entire point. Carbohydrates help you sustain moderate to high-intensity work because they can deliver energy at a rate fats cannot match. When glycogen becomes limited, fatigue shows up not as a dramatic collapse, but as an inability to hold pace, repeat sprints, or maintain power.