Human Nutrition Basics

Are you looking to understand what our bodies need to survive at a basic level? Then this is the article for you!


  1. Our body needs fuel to make energy, and materials to repair and build.
  2. Our body uses both fats and carbohydrates for energy.
  3. Our body uses protein to repair and build new cells and tissue.
  4. Our body requires vitamins and minerals in the right amounts.

Our body uses energy to build and repair

which means

Our body needs fats and carbohydrates to be able to use protein

Vitamins and minerals are required for good health, and found in an biologically optimal diet.

Fresh, purified water is preferred for hydration. It should be consumed as needed, rather than trying to drink an “ideal amount”. Food and drinks such as milk also contribute to total fluid intake.

Human Fuel

When we sleep, or go for a few hours without eating carbohydrates, our bodies naturally use fat for energy. Fat is a natural, optimal source of energy. When the body is using fat for energy, this is called “ketosis”. This means your body is using ketones (from fat metabolism) for energy.

The body can also use carbohydrates for fuel. These can be from starchy foods like bread, potato, and cereal, or from simple sugars like fruit, candy and soda. When the body digests the starchy foods, the long molecules get broken down into simple sugars. This means that no matter what kind of carbohydrate, eventually the body will absorb glucose or fructose (fruit sugar).

A 70kg person’s bloodstream can only hold about 4g (1tsp) of glucose at a time. To make sure it stays healthy, the body must deal with the extra glucose in the blood. Diabetics have difficulty managing the amount of sugar in their blood, which is why they can go into a coma if they don’t inject insulin. A healthy body has a functioning pancreas which releases insulin in response to raised glucose levels. This insulin causes the glucose in the blood to be converted into fats, which is then stored in the cells for use later. If the body is in this “storage mode” then it cannot use fat for energy. This is why people gain weight and struggle to lose it, because they do not leave enough time for their body to use their fat stores.

When someone waits a few hours before eating again, then the level of insulin will drop, and they will start to use fat for fuel. If this person usually has a diet high in carbohydrates, then this drop can make them feel tired and “hangry”. A diet which is lower in carbohydrates will cause less severe ups and downs, and help to give a more even-feeling of energy throughout the day. The chart below shows the difference in insulin levels between a high carb diet (black) and a low carb diet (red). You can see that insulin spikes and drops in response to the high carb meal, which can be described as a “carbohydrate roller coaster”.

The Carbohydrate Rollercoaster

The body does not need any carbohydrates to be healthy, however in modern life, this is very challenging to achieve and not necessary for great health. The average modern diet contains about 300g of carbohydrates a day. Keeping carbohydrates below 100g per day for an adult can make a huge difference to health, although people with chronic health problems may try to eat below 50g or even 20g per day.

How do you control the carbohydrates without counting? Make sure you eat plenty of healthy fats from meat, butter, eggs and dairy (plus protein), which will fill you up and give you plenty of energy. After a healthy and satisfying meal, you can have a sweet treat, which you will be less likely to overeat now that you are well-fed. Try choosing whole fruit and nuts as a treat, and only buy “fun size” candy to control portions.

Human building blocks

The body needs protein to build and repair itself as we live our lives. Protein is actually a name for a whole group called “amino acids”. The body uses different amino acids for specific purposes, and therefore it is important to get enough of all amino acids. Meat, poultry, eggs, dairy, and fish are complete sources of protein because they contain all 9 essential amino acids.

It is common to hear that grains and beans have protein, but they do not have all the amino acids needed for health. They can also cause problems such as “leaky gut” where the lectin proteins break open the space between the cells in the gut lining, allowing waste material and pathogens to enter the bloodstream. This is why it is important to only eat these foods in moderation.

By combining healthy animal proteins with essential fats, the body has everything it needs to survive. The body will die if only fed lean meat (known as “rabbit starvation”) or only fed sugar and fat (the majority of our modern diet).

Vitamins and Minerals

We have all heard about vitamins and minerals, as they are commonly added to processed food to make it sound healthier in the advertisements. But what are they, and where do they come from?

Protein and fats are macro-nutrients (needed in large amounts) and vitamins and minerals are micro-nutrients (needed in small amounts). Vitamins are organic and break-down easily with storage and cooking. Minerals are inorganic and more stable. Some vitamins and minerals are needed in larger amounts, and some are only needed in trace amounts. A whole food diet with a foundation of animal foods will provide these nutrients in the right amount.

All essential vitamins and minerals can be found in animal products.


CalciumMilk, yogurt, cheese.
CholineMilk, liver, eggs.
ChromiumMeat, poultry, fish.
CopperLiver, seafood.
FolateLiver, seafood.
IodineSeafood, dairy.
IronRed meat, dairy.
MagnesiumYogurt, salmon, red meat.
MolybdenumLiver, milk.
PhosphorusMeat, eggs, dairy.
PotassiumSalmon, milk.
SeleniumOrgans, seafood, dairy.
SodiumSeafood, salt.
ZincRed meat, seafood.


Vitamin A (retinol)Liver, salmon, butter, dairy.
Vitamin B1 (thiamine)Meat, eggs, liver, milk.
Vitamin B2 (riboflavin)Dairy, eggs, liver, meat, salmon.
Vitamin B3 (niacin)Liver, meat, fish, poultry.
Vitamin B5 (pantheonic acid)Liver, beef, poultry, dairy.
Vitamin B6Poultry, organs, fish.
Vitamin B7 (biotin)Liver, meat.
Vitamin B12Meat, poultry, fish, dairy.
Vitamin CFresh fruits, organ meats, fish eggs.
Vitamin DFatty fish, sun exposure.
Vitamin E:Paua (abalone), salmon, crayfish, tallow.
Vitamin KLiver, meat, fish, eggs, tallow.

It is pretty clear that liver is a super-food! It’s nature’s own multivitamin. This is why our ancestors prized this part of the animal as the most valuable, often giving it to the old, sick or pregnant members of the tribe. It can be tricky to incorporate it if you are not used to the unique flavour. Adding it to mince can help to hide it, or try liver and onions as a side dish.

Magnesium is lower in animal foods than the other minerals, so adding some pumpkin seeds and almonds to trail mix, plus taking a supplement, can help to cover any deficiency, which is found in about half the population due to industrial agriculture and food processing.

Plant foods do contain some vitamins and minerals, but many also bind vitamins and minerals, preventing absorption. For example, carrots contain Vitamin A as beta-carotene, but this must be converted in the body to the usable form (retinol), and many people do not have the genetic adaptation to do this. Another example; spinach contains calcium in the form of calcium oxalate, which is unusable to the body. Instead, it causes damage in the body, such as intestinal and circulatory system damage, and forming kidney stones. Even breads can hinder mineral absorption, such as a study on zinc, which showed that when oysters are eaten in a tortilla, almost none of the zinc was absorbed (see chart below). This means it is best to eat these foods as a side dish (or separately), rather than as the bulk of the meal.

Zinc absorption with or without tortilla and frijoles.

Vitamin C is also a nutrient of great importance, and has been shown to have many vital and incredible health effects. There is little danger with including a daily Vitamin C supplement, as the body will excrete any excess that it does not need. Eating a sweet mandarin orange every day will help provide Vitamin C too, plus a little extra fiber to help bowel function. However, if you are following a ketogenic diet, your requirements will be lower due to the fact that vitamin C competes to use the same metabolic pathway as glucose, which is greatly reduced by avoiding carbohydrates.

Toxic foods

Modern diets are full of easy, convenience foods. They were a result of food manufacturers making foods more shelf stable, and tasty. Billions of dollars are spent on developing the “perfect bite”, with the most addictive flavour and texture that food scientists can engineer. Their job is to hijack our biological senses, which evolved to seek out seasonal fruits, and instead make us crave these same sugar highs all year round. However, these high sugar foods are linked to chronic diseases, such as diabetes.

Vegetable oils (actually made from plant seeds, not vegetables) were also invented at the start of the 1900s, so they are a substance totally foreign to our bodies. They were initially made as an industrial by-product, but their low cost made them popular with convenience food manufactures. There is now strong evidence that these polyunsaturated vegetable oils (PUFAs) are also linked to our disease epidemic, as the rise of chronic diseases can be closely charted with the rising consumption of these PUFAs (see charts below).

Therefore, a diet based on our evolutionary history as apex predators (as shown by stable isotope analysis of ancient human remains) will ensure that nutritional needs are met, and give the best chance of living a long and healthy life.

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