What Macronutrients Do For Your Body.

4 Minutes Read.

What are Macronutrients?

These are nutrients that we need in larger quantities to give us energy. They are carbohydrates, proteins and fats. You need a balance of these food groups because they can affect how satisfied you feel with your meals and whether you are getting all the nutrients you need.


These macros are your body’s main fuel. They provide energy for your muscles, central nervous system and red blood cells. Carbs are broken down into glucose or sugar molecules, which also provide energy for your brain. Glucose is stored as ‘glycogen’ in your muscles and liver for later use when your body needs energy such as, after a period of fasting, for example. If there isn’t enough glucose available for you, i.e. you’re on the keto diet or your body struggles to regulate insulin due to conditions like diabetes, for example, then your body can get its energy by breaking down proteins and fats.

The calorie content of carbs is 4 calories per gram and depending on your individual needs, 45-65% of your daily calorie intake should ideally come from them.

Best sources of carbohydrates in your diet are:-

  • Low-fat or non-fat dairy or alternatives.
  • Whole grains.
  • Fruit and vegetables.
  • Legumes.


Foods with refined flour like crackers, breads, biscuits, cakes and cereals.

Fruit juices and soda drinks.



These macros are essential for many processes in your body and are digested into amino acids. We have 20 amino acids but 9 of them are not made by your body so therefore, they have to come from the food you eat. They provide structure to your tissues like cell membranes, organs, muscles, hair, skin, nails, bones, tendons, ligaments and blood plasma. Also, they are involved in your metabolic, hormonal and enzyme systems and help to maintain the *acid-base balance in your body.

* This is the state of your body having the right amount of acid and base, (substances that can neutralise acids by reacting with hydrogen ions) in your blood and other body fluids. Maintaining a normal acid-base balance is essential for your body to work the way it should.

Like carbs, the calorie content of protein is 4 calories per gram.

Depending on your individual needs like your age, activity levels, medical conditions and health goals, you need 0.75g of protein per kg of bodyweight each day.

Best sources of protein in your diet are:-

  • Animal proteins like meat, poultry, fish, seafood and dairy.
  • Soya products.
  • Lentils and beans.
  • Nuts, seeds and low fat nut butters.
  • Whole grains, such as quinoa, oats and brown rice.

Limit or avoid bacon, hotdogs and luncheon meats. And only eat 18oz of red meat per week.


As well as energy reserves, fats are needed for insulation and protection of your organs and for absorption and transport of fat-soluble vitamins.

Best sources of fat in your diet are:-

  • Vegetable oils such as olive, canola and avocado.
  • Fatty fish like salmon, fresh tuna and sardines.
  • Avocados.

About 20-35% of your daily calories should come from fat with less than 10% of your total daily calories from saturated fat. The calorie content of fat is 9 calories per gram.

sliced avocado fruit
Photo by Foodie Factor on Pexels.com
  • Seeds like flax seeds and chia seeds.
  • Olives.
  • Nuts and nut butters.

Avoid or restrict:-

  • Coconut oil.
  • Butter, cream and cheese.
  • Fat on meats and poultry.
  • Fried foods.
  • Shortening.
  • Soft margarine.
  • Packaged baked goods.

How do you know how much macros to eat?

As a general idea, follow a plant-based diet. (Don’t worry; you can still eat meat and dairy!) Fill 2/3 of your plate with whole grains, vegetables, fruit, nuts and seeds. For the last 1/3 of your plate, you can eat lean protein like chicken and fish or plant proteins like beans, quinoa or tofu.

However, it does depend on other factors. For example, children and teenagers need more calories from fat then adults for brain development. Older adults aged 65 or older need more protein to preserve their muscle mass; in fact, it is recommended that they should aim for 1-1.2 grams per kg of bodyweight per day.

Athletes and very active people need more carbohydrates and protein than those who are less active. Protein, to support muscle building after exercise and carbs, to provide calories to replenish their energy stores.

For those of you who are trying to lose weight, you could reduce your carb intake slightly, under the recommended daily intake and increase your protein intake slightly, above the recommended daily intake. The extra protein would help with satiety, while fewer carbs can promote a calorie deficit. (When you burn more calories than you eat or drink.)

So, I hope I’ve shed a little light on macronutrients. As usual, feel free to comment on this post.

Thank you for reading.

Rachel x

Sources: bhf.org.uk, mdanderson.org, healthline.com, cancer.gov, byjus.com, health.com, webmd.com, verywellfit.com, medicalnewstoday.com, mynutrition.wsu.edu

4 thoughts on “What Macronutrients Do For Your Body.

  1. This was a really useful breakdown especially as I have had to change my diet quite significantly recently (focusing on higher fiber and low carb, and very low added sugar). A really useful post — thanks!

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