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The Beginner's Guide to Nutrition

Written by James Collier BSc (Hons), Registered Nutritionist, who devised the Huel formula. He has over 25 years of experience working in nutrition and dietetics, including 7 years as a Clinical Dietician in the NHS. Covering an array of clinical areas, he worked with people with a wide range of ailments and food intolerances. He also has an Honours Degree in Nutrition with Dietetics: read more about James here.


What our body needs

In terms of human nutrition, there are a number of essential and conditionally essential nutrients in the following groups:


No matter which of the specific elements we consume, the primary requirement from food and drink is energy. Although the metric unit for measuring energy is kilojoules (kJ), calories are the more commonly referred to unit when speaking about food energy; although when we use the word ‘calories’, strictly speaking we mean kilocalories and the abbreviation is kcal.

To work out how many calories your body needs, this is a useful calculator to give you an approximate figure, although there are numerous factors that can have an effect:

There are two main figures:

If we eat more calories than the body needs, it will either be stored as fat or, if we have provided the right stimulus, turned into muscle. If we eat under our calorie requirements, we will lose fat and if we eat the correct amount we will maintain our weight.

The basic rough rule of thumb is:

  1. Consume your TDEE if you want to maintain weight
  2. Eat 500 kcal over your TDEE if you want to gain weight
  3. Consume 500 below your TDEE if you want to lose weight

1lb of fat is roughly 3,500 kcal; so if you consume a 500 kcal deficit per day in 7 days you will be 3,500 kcal under your requirement and therefore you should lose 1lb of fat per week, and vice versa if you are trying to gain weight. You often hear people say ‘I’m eating good / clean food, but I’m still gaining fat!’ It’s not chocolate that makes you fat, it’s too many calories, basically.

Once you have your calorie target the next step is work out your macro split.

What macronutrients you need

Ideally we need a mixture of all three macronutrients: carbs, fats and protein. Of the three, both fat and protein are essential, whereas carbs are not essential as they are only an energy source. Having said that, protein is a lot more expensive, so if you are using that as energy it's a waste of money. Carbs are also a more efficient energy source. Hence carbs are usually the bulk of a lot of diets.


Fat is a word which conjures up negative thoughts when we hear it; we tend to mentally associate the word with poor nutrition and we have traditionally been encouraged to cut down of levels of fat in our diet in order to promote good health. The truth is in fact very different: fat is essential. Fat is needed for growth, development and cell function; 60% of the brain is made up of types of fat; without fat we will die. However, there are lots of different type of fat and not all are beneficial.

There are two completely essential fatty acids (EFAs) that humans require: linoleic acid (LA – an omega-6 fatty acid) and alpha linolenic acid (ALNA – an omega-3). Although not essential, there are four other fatty acids that are useful and can reduce the requirement for LA and ALNA: arachidonic acid (AA), gamma linolenic acid (GLNA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). If you do not include much of these four in your diet, then make sure you’re including plenty of foods that contains LA and ALNA.

Essential and 'conditionally' essential fatty acids, their classification and principal dietary sources

Fatty acid Type of PUFA* Rich dietary source
Linoleic acid (LA) Omega-6 Corn, safflower, sunflower, soyabean, peanut oils
α-linolenic acid (ALNA) Omega-3 Flaxseed, soyabean, rapeseed oils
Arachidonic acid (AA) Omega-6 Small amounts in animal fats, egg yolk
γ-linolenic acid (GLNA) Omega-6 Corn, safflower, sunflower, soyabean oils
Eicosapentaenoic acid (EPA) Omega-3 Oily fish
Docosahexaenoic acid (DHA) Omega-3 Oily fish

*PUFA is polyunsaturated fatty acid


Protein is an essential nutrient which helps form the structural component of body tissues and is used within many biological processes. For example, protein is used to make enzymes, antibodies to help us fight infection, as well as DNA the building blocks to life.

Amino acids: we need to consume the 9 essential amino acids
Protein is made from amino acids. There 20 different types of amino acids, but 9 of them can’t be made by the human body so we have to consume them.

The 9 essential amino acids are:

All protein sources are not equal; some are classed as ‘complete protein’ and some are not. A complete protein source is one that contains an adequate amount of all nine essential amino acids.

Generally, proteins derived from animal foods (meats, fish, poultry, milk, eggs) are complete. Proteins derived from plant foods (legumes, seeds, grains and vegetables) are often complete as well (examples include chickpeas,black beans, pumpkin seeds, cashews, cauliflower, quinoa, pistachios, turnip greens, black-eyed peas and soy). Some plant foods tend to have less of one or more essential amino acid. Some are notably low, such as corn protein, which is low in lysine and isoleucine.

Certain traditional dishes, such as Mexican corn and beans, Japanese soybeans and rice, and Cajun red beans and rice, combine grains with legumes to provide a meal that is high in all essential amino acids.

Even if a protein source is complete, you still need to ensure you consume enough of that source to ensure you that you consume enough of the essential amino acid. A protein or amino acid supplement can be useful for those trying to build muscle.


Carbs are a cheap and effective energy source. There are basically two types: simple and complex. Simple carbs are sugar, etc, which are fast acting; in other words the body gets them into blood stream quickly - this is the sugar rush. Complex carbs may be digested more slowly, but some are still broken down quite quickly. Complex carbs include rice, oats, potatoes, couscous, quinoa, etc. Glycaemic Index (GI) is a guide for how slowly carb foods are digested and absorbed. Anything with a low GI is a slow carb and anything with a high GI will be a fast carb. Basically stay away from fast carbs, you don’t need them and they cause an insulin spike, which is turn causes the body to stop burning stored fat and instead opens the fat cells to store more fat.

GI Tables here:

What micronutrients you need

Micronutrients are vitamins and minerals. Through lots of medical research a list of essential vitamins and minerals were published by the UK government in 1991 as Dietary Reference Values (DRVs) and there are also the EU Guideline Daily Amounts which are pretty similar. See below:

Guideline Daily Amounts:
Vitamin A (μg) 800
Vitamin D (μg) 5
Vitamin E (mg) 12
Vitamin K (μg) 75
Vitamin C (mg) 80
Thiamin (mg) 1.1
Riboflavin (mg) 1.4
Niacin (mg) 16
Pantothenic acid (mg) 6
Vitamin B6 (mg) 1.4
Folic acid (μg) 200
Vitamin B12 (μg) 2.5
Biotin (μg) 50
Potassium (mg) 2000
Chloride (mg) 800
Calcium (mg) 800
Phosphorus (mg) 700
Magnesium (mg) 375
Iron (mg) 14
Zinc (mg) 10
Copper (mg) 1
Manganese (mg) 2
Fluoride (mg) 3,5
Selenium(μg) 55
Chromium (μg) 40
Molybdenum (μg) 40
Iodine (μg) 150

There are DRVs for most, but not all, nutrients. A population has a wide range of requirements, so the DRV Panel based the levels on the normal distribution curve with the Estimated Average Requirement (EAR) being enough to cover 50% of the population and the Reference Nutrient Intake (RNI) being sufficient to cover at least 97.5% of the population. There will always be extremes, so it is considered that, for most nutrients, supplying an intake equal to or above the RNI will be sufficient.

Ensuring you get sufficient quantities of all the listed vitamins and minerals can be tricky, so you must eat a wide variety of different foods including plenty of fruit and veg.

Summary of the advice

  1. Calories are key for weight control - if you want to lose fat aim for 500 kcal below target, and if you want to add muscle add 500 kcal. 500 kcal x 7 days = 3500 kcal which is about 1lb per week of fat loss
  2. Aim for at least 1 gram of protein per 1 lb of lean body weight; ensure you eat good fats (omega 3s and 6s) and make the rest up in complex carbs
  3. Ensure you get all your micronutrients by eating a balanced, varied diet
  4. The best diet is the one you can stick to. Nothing is perfect, but it can be perfect for you. 
  5. Whole foods are richer in micronutrients than processed foods
  6. Optimal health goes beyond just nutrition - ensure you get quality sleep, regularly exercise, reduce stress, and ensure you’re well hydrated 

Further reading:

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