Module 10 · Food, hydration & energy · Strong evidence

Nutrition basics

What protein, carbohydrates, fats, fibre, vitamins and minerals do — in plain words.

7 min read · Level: Beginner · Free — no account needed to read

The idea

Food provides three main macronutrients. Carbohydrates are the body’s main energy source — whole grains, fruit, vegetables and legumes release energy more steadily than sugary foods. Proteins build and repair tissues. Fats provide energy, help absorb some vitamins and are part of every cell; unsaturated fats (in oils, nuts, seeds and fish) are generally healthier than saturated and trans fats.

Fibre, found in plant foods, supports digestion, helps you feel full and is linked with lower risk of several diseases. Vitamins and minerals — needed in small amounts — support everything from immunity to bones. A varied diet with plenty of plant foods covers most people’s needs.

Some people have specific needs: during pregnancy, with certain health conditions, restricted diets or older age. Those are worth discussing with a doctor or dietitian rather than guessing.

Why it works

Knowing what different foods do makes food labels, headlines and advice easier to understand — and easier to question.

A real example

The situation

Aisha feels tired all the time and assumes she needs to eat less carbohydrate because of a video she saw.

What happened

Learning the basics, she realises her diet is low in fibre and protein rather than high in carbohydrate. She adds lentils, eggs and whole grains, and her energy improves. When the tiredness doesn’t fully lift, she also sees a doctor, who checks her iron.

The takeaway

Understanding the basics helped her ask better questions — of the video and of her doctor.

Use this when you are…

• food headlines confuse you
• you want to understand what your body needs
• someone recommends cutting a whole food group

Common mistakes

• Cutting out whole food groups based on trends.
• Assuming supplements can replace a varied diet.
• Ignoring fibre, which many diets lack.

What the evidence says

Strong evidence: Many good-quality studies, usually including randomised trials and reviews that pool them, point the same way. Guidelines tend to recommend it.

The roles of macronutrients, fibre and micronutrients are well established in nutrition science. Optimal amounts vary by person, and much popular nutrition advice goes well beyond the evidence.

Where this comes from: WHO healthy diet guidance; Nutrition research.

Fields that study this: Nutrition science.

Try it now: Check your fibre

1. List the plant foods you ate yesterday: vegetables, fruit, whole grains, legumes, nuts.
2. Count how many different ones there were.
3. Plan one more for tomorrow.

Questions to think about

• What nutrition claim have you believed without checking?
• Where could more variety come into your meals?

Try this today

Eat one more plant food today than you did yesterday.

Afterwards, ask yourself

What did understanding the basics change about how you see your meals?

Words in this lesson

• Ultra-processed food — Foods made mostly from ingredients extracted from foods or made in factories, such as many packaged snacks and soft drinks. How much processing itself harms health is still debated.