What is Nutrition Part 2: The next level – Macronutrients and Fibre


As discussed in Nutrition Part 1, nutrition can be viewed in terms of a hierarchy of importance. I talked about calories and how the balance between in and out will dictate weight loss and weight gain, but then I hinted that there might be more to it. Some of that will be explained here as we delve into the next level of the pyramid, macros.


‘Macronutrients’ is a collective term for the nutrients found in food that are needed in the largest (macro) amount. We actually measure them in grams. You may or may not have heard this word before, but you are probably familiar with the terms protein, carbohydrates (often shortened to carbs) and fat.

These are complex bundles of molecules that are found in all foods in varying amounts, and each one does something different when put them in the body. They all have an energy value, meaning that it is the macronutrients in the foods we eat which contain the calories mentioned above. Protein and carbs both contain 4 kcals per gram, whilst fat contains 9. This means, simply, that a food which contains 10 grams of fat, 20 grams of protein and 50 grams of carbs will have 370 kcals, as worked out like so:

  • 10g fat – 10x9=90. 90 kcal
  • 20g protein – 20x4=80. 80kcal
  • 50g carbs – 50x4=200. 200kcal
  • 90+80+200 = 370kcals.

Fortunately for us, this is all detailed on food packages, and we can even use various mobile phone apps to do it for us, so no maths is actually required.

So, that’s where calories come from. But I mentioned above that these macro’s all do different things in the body, and that means we need to look at them a little closer in order to determine what we should do with them. I’ll start with protein, as it is the most important one for achieving optimal performance, health and body composition.

Protein is made up of chains of molecules called amino acids. There are 20 amino acids in total, 9 of which are ‘essential’ meaning that we need to get them via food, as our body can’t make them out of other things. You don’t really need to know a lot more about amino acids for now other than the fact that all 9 amino acids that are essential are found in foods such as meats, fish, poultry, eggs, dairy, the grain quinoa, and soybeans, but are also found in different ratios in beans, wholegrains and some seeds which must be combined to make ‘complete proteins’. To read more about this, check out the article on vegan and vegetarian eating to learn more about food combining.

We consider protein to be the most important macronutrient when calculating your nutritional needs because we cannot really store it in the body other than in muscle tissue, contrast that to carbohydrates and fat which can be stored for later use. If you do not consume enough protein for your daily needs, your body will start to break down muscle tissue to get it. And this is bad.

Protein is not just used to build muscle, though. Oh no! It’s used for muscle repair too. When we exercise we cause small amounts of trauma to the fibres that make up our muscle tissue, and this needs to be repaired before we can use the muscle again properly. Dietary protein is used for this function, meaning that taking your diet from protein insufficiency to protein sufficiency will improve your recovery rate and enable you to train harder, boot camp to boot camp!

Put simply, if you don’t eat enough protein, when you lose weight it will of course come from fat stores but also from muscle stores, meaning that you risk looking worse, feeling worse, and slowing down your metabolic rate*.

*Metabolic rate is the speed at which you burn calories in any given day. Muscle weight burns more calories than fat weight when you move about because it has to work hard just to stay active and alive. This means that if you lose muscle, it gets harder and harder not to put fat back on.

How much of each food group is enough?

Protein needs

The general public tend to get too little, whilst the training community almost always get too much. The latest figures we have for maximising the effects of protein consumption are 2.3-3.2grams of protein per kilogram of lean body mass (2). But the leaner you are, and the lower your calorie target is in relation to your overall needs, the more protein you need too. The number I tend to go with is 1.6-2 grams per kilogram of bodyweight, unless you are very overweight, in which case I would use 1.6-2 grams per kilogram of your ideal bodyweight (which is how much you would weigh if you were a bit leaner, as large amounts of bodyfat don’t actually affect protein needs much if at all). Which end of that scale you fall at matters a lot if you want to build the most muscle possible, but if you’re just looking to get fitter and stronger, the lower end will be just fine.

When focusing meals around a protein source, it gets really easy to start to see the protein numbers add up. Plan your meals ahead of time to make sure you don’t have to play ‘catch up’ in the evening.

Fats, the other essential macronutrient

We need fats for hormonal production, cell membranes, skin moisture and fighting free radicals (the leftover bits that fly around our body after cells have used oxygen for energy. These free radicals cause damage to other cells and over time can affect our health).

Fat is broken down into different categories depending on molecular structure, you may be familiar with a few of them.

Monounsaturated Fats found in nuts, nut butters, olive oil and avocadoes. These are universally recognised as ‘good fats’.

Polyunsaturated Fats found in grains and fatty fish. These fats include the Omega-3 fats, EPA and DHA which are the ‘good fats’ you get from fish oil. These get a special mention as numerous reports (3) suggest that consuming around 2-3 grams of these two combined per day can have profound health benefits. Read this article about supplements for more information.

Saturated Fats are a point of contention. They are found in meats, eggs, dairy and other animal sources, and were demonised a large amount in recent years due to being implicated in various health issues. Fortunately, data is now readily available which thoroughly debunks the idea that saturated fats are universally ‘bad’ and so long as they are consumed as part of a balanced diet they can even be beneficial! So, saturates from whole food sources are 100% on the menu.

What is Nutrition | British Military Fitness

Trans fats are found in trace amounts in animal products, which is fine, but they are also found in large amounts in some packaged, highly processed foods. These man made fats are created by hydrogenation of plant fats (you may see hydrogenated oil appear on a label) and can cause havoc to our health. They are best avoided, in there man made form, entirely if you can.

The first three fats mentioned above are all beneficial to our health and should be included in our diet in roughly equal measure. To accomplish this, simply eat a balanced and varied diet whilst considering supplementing fish oil if you do not eat oily fish on a regular basis.

How much should you eat? Dietary fat should make up around 30% of your total intake, so for someone who calculates that they need to eat 3000 calories, roughly 900 of those should be fat, so 100 grams or so. This isn’t a hard and fast rule though, and more or less fat may make you personally feel better, so experimentation is a good idea.

And carbs...

This brings me to carbs which are found in large amounts in potatoes, fruits, some veggies, grains or grain based products such as bread and pasta, and a lot of confectionary. Carbs are a non-essential macronutrient as we can make them out of both protein and fat if we need to. Some people have taken this to mean that we don’t need carbs, but for people such as BMFers that are taking part in intense boot camp training, nothing could be further from the truth.

Carbs serve primarily to provide us with energy. Our cells use them to perform intense tasks which last a few seconds, such as sprints or heavy lifting, to keep mental function working properly (the brain uses glucose, which is what your body turns carbs into, exclusively under normal circumstances. There are a few exceptions, but that goes beyond the scope of this article) and to do day-to-day things provided stores are sufficient.

Carbs should make up the rest of your dietary intake, which is determined by subtracting the caloric value of your protein need and fat intake from your daily total. For example, our 3000 kcal person above would do this, assuming he weighs 80kg:

  • 160g of protein gives 640kcal (160 x 4 calories per gram of protein)
  • 100g fat gives 900kcal (100 x 9 calories per gram of fat)
  • 640+900 = 1540kcal
  • 3000 – 1540 gives 1460kcal left over.
  • 1460 divided by 4 gives 365g of carbs.

What kind of carbs is a little trickier than it may seem. Carbohydrate sources should be decided based upon three factors, two of which I’ll talk about immediately; namely how you feel, and your health. Carb sources, as mentioned above, include fruit and vegetables which contain micronutrients and will fill you up. They can give you steady supplies of energy which may make you feel good for a longer time, too, which will make it easier to stick to what you are doing, as well as improve your results from training as you can train harder with good energy levels. Because of these factors, carb sources should be almost exclusively single ingredient, natural, fresh (or frozen) whole foods which are as minimally processed as possible. The top class carbs I advise most people to stick to at least 90% of the time are vegetables, fruits, potatoes (all kinds), rice, beans/legumes and whole grain products.

The other carb sources available, such as confectionary, processed cereals and baked goods can be included in your carb allowance, sure, but this needs to be carefully balanced with a majority of ‘good stuff’ to ensure you feel great and perform at your best. Know that these foods aren’t harmful or inherently fattening, but they are far from optimal for our health and wellbeing.

And finally, fibre

Fibre is the indigestible part of carbohydrates. It improves digestive health, glucose tolerance (meaning you feel better after eating carbs, including sugary ones), satiety levels (keeps you fuller for longer) and can reduce your risk of some diseases. It may not seem cool, at the mention of fibre you probably start thinking of your grandparent’s weird bran cereals, but by including enough fibre in your diet you will be far healthier overall, and without HEALTH, body composition and performance will take a dramatic knock.

How much is enough? Get 10-15 grams of fibre per 1000 calories you consume. (E.g. a 2000 calorie diet needs 20-30 grams).

As you can see, getting your calories in line will allow you to gain or lose weight, but getting your protein, fat, carb and fibre levels in line will allow you to lose fat, specifically, gain muscle, stay alert, function optimally, become healthier, perform more effectively in boot camp and feel great!

Feeling great needs more than macros and fibre, though. We need micronutrients, too. In fact, in my opinion micronutrients are as, if not MORE important than macronutrients in some ways. Check out the last article in this series, Nutrition Part 3, to find out about the rest of the pyramid, and get a great baseline understanding of what nutrition really is!


References for the ‘What is Nutrition?’ series.

  • (1)    www.who.int/topics/nutrition/en/
  • (2)    Helms et al. (2014). ‘’Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation’’. JISSN
  • (3)    http://examine.com/supplements/Fish+Oil
  • (4)    Aragon and Schoenfeld. (2013). ‘’Nutrient timing revisited: is there a post-exercise anabolic window?’’ JISSN
  • (5)    Norton et al. (2012) ‘’ Leucine content of dietary proteins is a determinant of postprandial skeletal muscle protein synthesis in adult rats’’. US National Library of Medicine
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