
"We eat foods, but we do not eat nutrition or nutrients. The food we eat is part of our nutrition and contains nutrients." JEUKENDRUP, 2014
The food we eat provides us nutrients that play physiological roles in our body. There are six categories of nutrients, which you can see below:

We can categorise the functions of nutrients further again:

Growth and development is largely a result of protein metabolism. All structures of the body are built up and regenerated through the processes of proteins.
Energy Provision primarily comes from carbohydrates and fats. Their structures are similar and metabolic pathways are interchangeable for energy production.
Metabolism Regulation is mainly the responsibility of proteins in the form of enzymes, and vitamins and minerals, which support the metabolism of the macronutrients.
MACROS
The macronutrients (macros), Carbohydrate, Fat and Protein are the energy giving nutrients. Although protein is not the preferred energy source, and is spared for growth and development, it can be metabolised for energy if energy availability is low.
One gram of carbohydrate or protein has 4 calories per gram stored in its chemical bonds. Fats contain 9 calories per gram. Learn more about calories here.
We don't just eat nutrients, though. The foods and meals we eat are made up of various combinations of the macros, and not all foods necessarily contain all three macros. Meat, for example doesn't contain carbohydrate, and most fruits or vegetables don't contain fats.
Micronutrients
Micronutrients are the vitamins, minerals and phytonutrients (plant nutrients) which perform a myriad of functions in the body, from supporting carbohydrate metabolism, forming cell walls from fats, and buffering oxidative stress (antioxidants).
While macronutrient intake can be tailored for desired physique or performance goals, a variety of whole foods, namely fruits and vegetables, should be consumed to meet the required micronutrient intakes. The details are best reserved for a future article. Today we delve into the MACROS.
Carbohydrates

Carbohydrates are made up of carbon (carbo), water (hydrate), and hydrogen.
We get almost all of our carbohydrate intake from plant sources. Or at least what once was a plant.
1g of Carbohydrates = 4 calories OR 17 kilojoules.
The carbohydrates of importance in respect to diet and exercise include glucose, sucrose, and starch. Carbohydrates can be broken into different classifications where types of carbohydrate can be grouped according to their chemical structure.
Sugars
Sugars are carbohydrates. Carbohydrates are made up of sugars. Sugar is not the enemy.
Monosaccharides are the single molecule units of carbohydrate & there are 3 found in our diet.

Polysaccharides are two molecule sugars, made up by any combination of the monosaccharides.
Oligosaccharides are combinations of 3 or more monosaccharides and are found in most vegetables.

Polysaccharides are long chains of between 10 and 20 monosaccharide combinations. Polysaccharides containing 20 to thousands of molecules make up starch, fibre or glycogen.

Glycogen
We store carbohydrates in our muscles and liver in the form of Glycogen. From our food, they're broken down into - or converted to - glucose, and then repackaged into glycogen to be stored.
In total we have enough space for up to 1000g of glycogen, depending on body size and muscle mass. When this storage site is full, carbohydrates can be converted to fat* for storage.
*IMPORTANT: This does not mean that eating more than 1kg of carbohydrate will cause you to get fat.
Our metabolism is in a constant state of flux between fat conversion, storing and utilisation, depending on the body's needs.
Absent of an energy (Calorie) surplus, excess fat storage cannot occur. Overall energy balance over a 24 hour period, determines fat storage / loss.

Each gram of carbohydrate stored in the body holds 2.7g of water with it. For this reason body weight can fluctuate from day to day, and within the same day.
It's also why people who adopt a very low carbohydrate ketogenic diet see rapid shifts in weight within the first few days. As glycogen stores are depleted, water weight is lost with it.
Carbohydrates and performance
Fuel for the work required.
Carbohydrate is NOT essential for life, as proteins and fats are. However, glucose is the preferred fuel source of the brain and the central nervous system, as well as red and white blood cells.
There are metabolic pathways for conversion of other substrates, like fat, so that our cells get the glucose that they need.
Although not essential for life, carbohydrate intake IS essential for reaching and maintaining higher intensity outputs in exercise and sport.
Beyond approximately 65% of Vo2max intensity, where fuel is needed fast, a larger percentage of glucose in the fuel mixture is needed.

In the graph here, we see how the two primary fuels, fats & carbohydrate are used when we move our body.
At low intensity it's predominantly fats and a small amount of carbohydrate. As intensity increases, the demand for each fuel incrementally switches, at which the cross over point is around 65% Vo2max.
If you are exercising at higher intensities, you need to be consuming carbohydrates to fuel these sessions. You also need to prioritise intake after training to ensure full recovery before your next training session.
Carbohydrate Food sources
Simple sugars - Monosaccharides & Disaccharides are found in the following foods:
Fruits and fruit juices
Sweets
Baked goods
Jams
Honey
Syrup
Candy
Sugar
Sports Drinks
Chocolate
Beer
Sugary cereals
Oligosaccharides are found in most vegetables
Starch - polysaccharides are found in the following foods:
Cereals
Potatoes
Pasta
Rice
Bread
Sweet potatoes
Corn
Beans and lentils
Fiber - polysaccharides are found in the following foods:
Wholegrain cereals & breads
Oats
Barley
Fruits
Vegetables
Protein

Everything we do, and everything we are depends on the action of thousands of different proteins
1g of Protein = 4 calories OR 17 kilojoules.
From a physique, performance and recovery stand point, protein is essential. But protein provides so much more for our health and function than just our muscles.
There are thousands of different proteins that play a wide range of functions from DNA synthesis to immune system regulation. The average adult holds 10-12kg of protein in the body.
Heres an insight to what role protein plays in our body:
Structure: In conjunction with essential minerals, protein plays an integral part of the structure of muscle, skin, hair, bones and nails.
Growth and development: Protein both signals the formation of new tissue, and provides the recourses for tissue formation to occur. For example, after weight training, adequate types and amounts of protein are needed to provide building blocks for muscle building, and to trigger the machinery that puts the blocks together.
Enzymes:
Enzymes are proteins. They accelerate biochemical reactions that are vital for digestion, energy production, muscle contraction and, much more.
Transport and storage: Proteins act as transporters of essential substances of life. Oxygen is transported by the haemoglobin protein. Vitamins and hormones are transported by Albumin proteins.
Hormones & Signalling: Some hormones are made of proteins, such as insulin, which shuttles glucose into our cells.
The insulin receptors on the muscle cell wall that signals the uptake of glucose are also made of proteins.
Immune health: Antibodies that fight off foreign invaders are formed by proteins. Proteins assist in the formation of inflammation, the necessary response to healing injured tissue.

What exactly is Protein?
Protein is made up of its individual building blocks, Amino Acids (AA). There are 20 AAs.
11 of them are non-essential, meaning we don't need to consume them through food, but can recycle and convert them within the body when needed.
9 of the AAs are essential (EAA), and therefore can only be obtained in the diet.
In digestion, protein foods are broken down into their individual AAs, which are absorbed and delivered around the body. Our cells will take them in and assemble them into
chains of linking amino acids (Polypeptides) of various sequences.
Food sources that contain all 9 of the EAAs are classified as "Complete" proteins, whilst those without are "Incomplete". Generally, meat and other animal based produce are complete protein sources. Most plant foods are incomplete, except for the select few, such as Soy and Quinoa.
Non meat eaters may be at risk of not obtaining a complete EAA profile, however it doesn't mean an adequate intake can't be achieved.
It would require some consideration to regularly consume complete plant based sources and combine foods to create a complete profile within a meal. One example would be rice and beans, both of which lack different EAAs, but together create a complete profile.
Check out this previous article to dive deeper into protein: How much you need, requirements for training, recovery and fat loss, and the best protein sources.
Fat

Fats in food and body fat do not necessarily go hand in hand.
1g of Fat = 9 calories OR 37 kilojoules.
Otherwise known as Lipids, Fats are essential for health. They should make up at least 20% of our total daily energy intake to ensure optimal function.
Fats play a role in cell wall structure, transport of essential nutrients (Vit A, D, E & K) and hormone formation. The Essential Fatty Acids, Omega-3 and Omega-6 have many health benefits, namely anti-inflammatory processes.
Still part of the common rhetoric, is that eating fats makes us fat. You may have heard the catchy phrase “from the lips to the hips”. As discussed in a previous post about Energy Balance, total calorie intake relative to output is what determine's weight/fat gain.
Fats are only fattening if they contribute to excess energy. As they are quite energy dense, with 9 calories per gram, this may be where excess energy can be accumulated. But Fat is not inherently "fattening".
What is Fat?

The fat found in our bodies is stored as adipose tissue (stuff you can pinch), within muscles, and also circulates in the bloodstream to wherever it's needed. These fats are called Triglycerides.
Triglycerides are also the primary fat found in the food we eat. To be used as an energy source they need to be broken down into their individual fatty acids and glycerol backbone.
When doing a fat loss phase, a calorie deficit influences a process called Lipolysis (Lipid Breakdown), where stored Triglycerides are broken down and liberated into the blood stream to supply energy to the cells.
Types of Fat
Saturated fats
Saturated fats are largely found in animal produce, butter, coconut oil and baked goods. They're solid at room temperature, compared to oils, which are predominantly rich in unsaturated fats.
High saturated fat intake is strongly correlated with high cholesterol levels, particularly "Bad" LDL cholesterol, and is associated with higher risk of heart disease.
Dietary Guideline recommendations for saturated fat intake is up to 10% of total energy intake, whereby higher intakes may increase disease risk.
Unsaturated fats
This category is broken down again into Mono-unsaturated and Poly-unsaturated fats.
They're found in varied amounts in oils, oily fish, nuts, seeds and avocado. Their chemical structure makes them liquid at room temperature.
Mono-unsaturated fats (MUFA)
The richest source of these fats is Olive oil. They’re also found in nuts, nut butters, seeds and avocado. As far as health impacts, MUFAs tend to be somewhat neutral. They're neither associated with increased or decreased disease risk.
When MUFA replaces saturated fats in the diet, reductions in LDL cholesterol, and increases in "Good" HDL cholesterol is seen, reducing heart disease risk.
Olive oil is considered one of the key health promoting components of the Mediterranean diet, but it's thought that the main benefit comes from plant chemical compounds, Polyphenols, likely having antioxidant and anti-inflammatory properties.
Poly-unsaturated fats (PUFA)
These can be broken down yet again to Omega-3 and Omega-6 essential fats. They're “essential” because the body can't produce them, thus must be consumed through the diet.
Omega-3 fats are found in fatty fish and other seafood, walnuts and linseeds. Omega-6 fats are found in plants and seed oils (safflower, sunflower, walnut).
Omega-3 fats have been at the center of nutrition research interest. They've been found to have heart and brain protective effects, largely due to their anti-inflammatory, anti-blood clotting, and blood vessel relaxing properties.
As seen with MUFA, when replacing saturated fat in the diet with PUFA, significant reductions in LDL cholesterol and heart disease risk is seen - More so than MUFA.
From a health perspective, selecting mono and poly-unsaturated fat food sources over saturated fat sources may have benefits of reducing visceral fat (fat which encases the central organs) and risk of fatty liver. Both of which are linked to heart disease and Type II Diabetes.
The "Fat Burning Zone"
You’ve probably heard of the “fat burning zone”, maybe even seen this as one of the settings on the treadmill at the gym. Theory is that cardio performed at 60-65% of intensity burns more fat. We saw this on the previous graph that this is actually TRUE.
At low intensities where fast energy isn't required, the body spares glycogen stores and prioritises fat for fuel. What happens mechanistically, however, doesn’t always play out practically for overall fat loss.
Let's use the following example:
Jane trains for 45 minutes in the fat burning zone, very conscious to not go over, in order to optimise fat loss.
Here, approximately 50% of the energy spent came from fat, and the other 50% came from carbohydrate.
If, within that 45 minutes, Jane trained at a higher intensity, or did interval training, she would have been using much more carbohydrate than fat for fuel. A 70 : 30 % split, for argument's sake.
Jane, in the fat burning session burned a total of 200 calories. The 50% from fat equates to 100 calories. At 9 grams per calorie, Jane burned 11-ish grams of fat.
In Jane's higher intensity session she burned 300 calories. The 30% from fat equates to 90 calories. Jane burned 10 grams of fat.
Not a big difference.
To what end?
The point here is not that one form of exercise is better than the other.
What matters most is the total caloric expenditure, contributing to the overall daily energy balance. Which fuel is used doesn't matter. In the long run, fat will be burned to make up for an energy deficit if there is one.
Select exercise based on preference, physical capacity and time availability. Moreover, you don't have to use exercise for fat loss. The calorie deficit can come from the food side of the energy balance equation, and exercise can be done purely for health and fun!
Summing Up
We don't eat nutrients. We eat food. Understanding the role of each macronutrient is helpful in shaping your overall dietary pattern, to then achieve our goals.
We understand that protein is essential for health and very beneficial for fat loss. We understand that carbohydrates may not be "essential" for health, but will likely promote better performance during higher intensity exercise.
We also know that fats are essential for health, providing that the major source is unsaturated. Fat does not make us fat, but rather, the overall calorie intake is what determine's weight gain or loss.
コメント