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Protein, fats and carbohydrates 101

All parts of our bodies – from our muscles and brains, to our hearts and livers – need energy to work properly and that energy comes from the food we eat. Food consists largely of combinations of the three macronutrients, protein, fats and carbohydrates.

A complex journey, that starts when we begin to chew and ends with gut bacteria squeezing out every last usable morsel, breaks it down into microscopic particles that are absorbed by our blood stream and shunted round for use in various bodily functions.

All three macronutrients can be used as fuel for our bodies – and we can even train our inner furnaces to preferentially burn one source more than the other, it’s how high-fat diets such as Atkins work. In order to better understand these concepts, it’s important to have a basic knowledge of protein, fats and carbohydrates, what they do and what the best sources of each are, so welcome to Nutrients 101…

First a word about the word ‘essential’

You may have read or heard about ‘essential fats’ or ‘essential amino acids’. Our bodies are sophisticated bits of kit and can often make some of the nutrients we need from other substances: for instance beta carotene, a red-orange pigment found some plants including carrots is converted into vitamin A which is vital for healthy skin, eyes and immune functions. There are other substances our bodies need, however, that we can’t make – and so these have to come from what we eat, and these are the ones classed as ‘essential’.

Healthy fish meal with potatoes and side salad


Aside from water, proteins are the most abundant molecules in the body as they are major structural component of all cells, but especially muscles. The building blocks of proteins are in turn called amino acids. There are 20 amino acids that are of use to us for a wide variety of functions.

Of those, 11 can be made by the body, while the other nine are essential in that they have to come from our diet. Amino acids are used for building muscle tissue and repairing damaged tissues, which is why you’ll see them in some sports supplements. For a long time, a side group of essential amino acids, branched-chain amino acids (BCAAs) were all the rage as they are needed to switch on muscle synthesis.

Recently, essential amino acid (EAA) supplements containing all nine have grown in popularity as research shows a better balance of all the EAAs may be better when it comes to muscle growth and recovery. Omnivores can get the full set of amino acids from animal products in their diet such as meat, seafood and dairy, while soy is the only plant source to contain all the EAAs. It’s why vegans and vegetarians need to make sure they consume a wide range of plant sources of protein to get them all in.

For those on a vegan/vegetarian diet, the most common combinations to ensure a full complement of essential amino acids are:
1. Grains (rice, corn etc) and legumes (peas, beans, lentils)
2. Seeds (such as sesame or sunflower) and legumes



In dietary terms, fats have been unfairly demonised for many years. Fat is actually essential for life – the walls of our cells are made up of saturated fat for instance. Where there is both confusion and misinformation is when it comes to how much fat you should have in your daily diet, what form it takes and where it comes from.

As a general rule, we need both saturated and unsaturated fats. Where issues do seem to occur is when we combine a diet of both high fats and highly processed carbs – this is likely to lead to metabolic syndrome, a condition that can be linked to obesity, type-II diabetes and a whole host of other issues.

As with proteins, there are some fats that are considered essential in that they have to come from what we eat.

The main ones are:

  1. Omega 3s: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA)
  2. Omega 6s: there are more than 10 of these, the most common being linoleic acid

Ideally the ratio of omega 3 to omega 6 in your diet should be 1:1 to help reduce inflammation. Good fats increase satiety and can be used as fuel by humans – even people who are extremely lean store tens of thousands of calories of fuel as fat. Nuts, seeds, avocados, fish oils, olive oil, coconut oil are good sources, but choose animal fat – other than fish oils – in moderation.

Baked bread and dairy produce


Carbohydrates are the easiest source of fuel for us to burn… However, no carbohydrate is essential: we can obtain all the energy we need from protein and fats and unless you are an extreme endurance athlete you can significantly reduce carb intake without any issues. Carbohydrates are generally broken down into ‘simple’ forms (sugars) and complex (starches from things like wheat, rice etc), although the reality is far more nuanced.

Processing carbohydrates tends to take any ‘goodness’ from them – so white bread for instance has most of the fibre taken out. By restricting carbs – especially simple sugars and ones with lots of starch – we can encourage our body to burn more fat. What we still need to do is have an adequate amount of fibre in our diet, so low glycaemic index fruit and green veg should make up most of your dietary carb content.

Shopping/eating list

Proteins: Eggs (lots), beef, chicken, pork, turkey, seafood (lots) full fat (FF) cottage cheese, FF Greek yoghurt, FF milk, cream cheese, protein shakes, soya products such as tofu, beef jerky, chia seeds

Good fats: olive oil, avocados, nuts, seeds (especially flax), fish oils, chia seeds, some coconut oil, some butter

Carbs to eat: Green apples, berries, spinach, kale, sweet potatoes, mushrooms, peppers, cauliflower, asparagus, aubergines, broccoli, Brussels, cauli, celery, onions, tomatoes, garlic, white potatoes (skin on)

Carbs to avoid or eat in moderation: white potatoes (with their skin off), white bread, white pasta, cakes, crackers, white noodles, white rice, sweets, alcohol – if you have these, make them the exception and only small portions.

Fibre: can be found in many of the fruit and veg above. It’s also beneficial to take a spoonful or two of ground flaxseed a day.

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