Macronutrients: The building blocks of your diet

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​All the food you eat contains nutrients, the substances that help your body function. There are two main types of nutrients.

  • Macronutrients are the building blocks of your diet – you eat these nutrients in large quantities (why they start with “macro”, meaning large).
  • Micronutrients are nutrients that you eat only in small quantities. They include vitamins and minerals such as vitamins A, C and D and calcium, iron and magnesium, to name just a few.

Food contains three macronutrients: fat, protein and carbohydrates. Each of them plays an important role in your body.


Among other things, fat:

  • gives you energy while you are resting or doing low-intensity exercise
  • helps the body absorb vitamins A, D, E and K, which rely on fat to carry them around the body
  • provides essential fatty acids – fats that the body needs from your diet to keep the heart healthy, help the brain function, make hormones and build healthy cells and skin.

Over the years, you might have heard to avoid “fatty foods”. However, not all foods that are high in fat are bad. This is because there are healthy (or good) fats and unhealthy fats.

Healthy fats

Fish such as salmon, for example, are generally a source of good fat, specifically omega-3 fatty acids. Other sources of good fats include nuts and seeds, vegetable oils and avocado.

You may hear that fish can contain high levels of mercury. It is true that larger fish can accumulate mercury over time, so try to avoid predatory (hunting) fish such as white tuna, shark and swordfish. That being said, the benefits of eating fish greatly outweigh the risks. Most types of fish are safe to eat. Examples include salmon, cod, haddock and sole.

There is evidence that omega-3 fatty acids can help ease inflammation, which can reduce pain. If you have pain from headaches, some research shows that a diet high in omega-3 and low in omega-6 (another type of fat) may lead to fewer days with a headache.

Unhealthy fats

Unhealthy fats include trans-fat and saturated fat. These fats should be limited in your diet because they can increase your risk of heart disease. Try to limit foods such as butter, hard margarine, lard and shortening, fatty cuts of meat and chicken with the skin on.

Be careful when you see food products that are advertised as “low fat”. Often, food manufacturers will add extra sugar, sweeteners or salt to make the food taste better. Over time, these may be worse for you than the fat that the manufacturer has removed. Talk to your healthcare team or registered dietitian about how to make healthy choices about low-fat food products.


Protein plays a range of roles in the body, including:

  • building and repairing muscles, organs, bones, skin, hair and nails
  • helping muscles work
  • helping to build enzymes to digest food
  • helping to build hormones.

In Canada’s Food Guide, the food groups richest in protein are meat and alternatives, such as chicken, beef, eggs, tofu, beans, peas and lentils, and milk and alternatives, such as Greek yogurt and cottage cheese.

One of the benefits of protein is that it helps you feel full for longer. Starting your day with a good source of protein, such as eggs, and including protein in every meal, will help to keep hunger at bay and make you less likely to snack mindlessly. It will also help you concentrate at school or work.


Carbohydrates play two main roles in the body. They:

  • are the body’s main source of fuel (energy)
  • provide fibre to help food pass through the digestive system and help keep you fuller longer.

The food groups richest in carbohydrates are vegetables and fruit and grain products.

Some people might fear carb-rich foods, such as pasta, bread or rice, believing that they lead to weight gain or bloating, but this ignores the different types of carbohydrates and how they behave in the body and the importance of healthy portion sizes.

  • Simple carbohydrates (sugars) are found in foods such as fruit juice, honey, sugar and candy. These foods tend to cause blood sugar levels to “spike“ and then fall quickly, which can leave you feeling hungry soon afterwards.
  • Complex carbohydrates (starches) are found in grains, vegetables and legumes (beans, peas and so on) and whole fruit. These foods are filled with fibre and are digested more slowly, meaning that they keep you full for longer. They are also good for your heart and help lower your cholesterol levels.

There is a place for simple and complex carbohydrates in your diet. For example, many fruits (such as strawberries, cherries, grapes and raisins) can help ease inflammation. Apples boost acetylcholine in the brain, a chemical that helps with memory, concentration and energy. In terms of vegetables, broccoli may protect the cartilage in your joints and is linked with a lower risk of osteoarthritis.

That said, it is best not to rely on simple carbohydrates for your energy. This includes juices and soft drinks, which often contain high amounts of sugar and sweeteners. And when it comes to choosing complex carbohydrates, aim for whole grains such as barley, whole wheat pasta and wholegrain bread and try to eat a wide range of vegetables.

Further information

Visit EatRightOntario’s Food Portions Toolkit​ to help you apply the recommendations for healthy eating.

Last updated: May 2nd 2016