Proteins, carbohydrates and fats: what are they and why do we need them?

If you’re interested in your diet, whether it’s for weight loss or just eating healthier, you’ll need to know a few things about the 3 main food groups: proteins, carbohydrates, and fats. In this article I will tell you what each of them is, why you need them and in what foods they can be found.


Protein is a part of every living cell in your body, including your skin, muscles, tendons, ligaments, hair, and the core of your teeth and bones. It also plays a role in many other functions, such as hormones (such as insulin), antibodies that fight infection, and red blood cells that carry oxygen throughout the body. One thing it isn’t often used for is power production. Although it can be very easy, this only happens in cases of extremely intense physical exertion or starvation, where not enough carbohydrates are available.

It is made up of what are called essential amino acids and non-essential amino acids. Non-essential amino acids can be made in the body and there are 12 of them, but essential amino acids cannot and all 8 must come from the food we eat.

Protein sources include meat, eggs, fish, cheese, and milk, but also nuts, beans, soy, oatmeal, lentils, and peanut butter. Obviously, there is no reason why a vegetarian shouldn’t get enough without resorting to supplements.

How much is enough?

Well, that depends on your weight and your activity level. The protein requirements of a person who does not have a physical job and who does not exercise can be calculated by multiplying their body weight in kg by 0.8.

So for a 60kg (132lbs) individual this would be 48g.

However, if you exercise regularly, this could rise from the 0.8 figure to anything up to 2g per kilo for a serious athlete or bodybuilder.

Protein provides 4 calories of energy per gram and should make up about 15% of your daily caloric intake. A diet where protein intake is consistently too low, as is possible with a poor vegetarian diet, can affect the benefits I just mentioned. But before you rush out and stock up on protein shakes, keep in mind that too much has its side effects, too. If you regularly have 30% more than you really need, you could be doing yourself more harm than good, in some cases causing liver and kidney problems, including kidney stones, which is just one of the reasons certain high diets should be avoided. high in protein and low in carbohydrates.


Carbohydrates have 4 calories per gram and should make up about 55% of your diet. They have various uses in the body. The main one is as an energy source called glucose which is stored in the body as glycogen. Glucose, which you may have seen as an ingredient in some energy drinks, is known as a simple carbohydrate that you may recognize better as sugar. This is absorbed into the body very quickly and won’t satisfy your hunger for long, which is one of the reasons it should ideally be avoided if you’re trying to lose weight. It also has a quick effect on energy levels giving a quick physical and mental high that is soon followed by a crash.

In contrast, the other form, complex carbohydrates, take longer to digest and provide a slower, more steady release of energy and keep you from feeling hungry for longer.

Examples of complex carbohydrates are rice, pasta, potatoes, beans, and oatmeal.

The rate at which each carbohydrate is absorbed is known as the GI, glycemic index. Each food can be assigned a number between 1 and 100 based on this, with pure glucose being absorbed the fastest and therefore assigned a GI of 100. At the other end of the scale, lentils have a GI of only 21 and therefore would be much more. It is better to keep you from being hungry for longer and maintain a more stable energy level. High GI foods also promote fat storage and thus weight gain by forcing glucose and fats already in the bloodstream into cells for storage.

There are no risks associated with eating too many carbohydrates, other than too much sugar can lead to diabetes. Not getting enough will lead to low energy levels, but not getting enough for prolonged periods can cause serious health risks if taken to extremes.


Fat has 9 calories per gram and should make up about 30% of your diet, as it actually has many vital uses in the body. These include protection of internal organs, insulation from cold, absorption and storage of certain vitamins, insulation of nerve cells, healthy hair and skin, and also as a source of energy. As you can imagine, not gaining enough weight can cause many health problems, but obviously this is not a problem for most people in the developed world who gain too much weight. As a result, they suffer from overweight, high blood pressure and coronary heart disease.

There are 2 types of fat, and while both are a necessary part of your diet, your intake of saturated fat should be closely monitored. The main source is of animal origin and is solid at room temperature. Examples include butter, bacon, cream, and meats. What makes it so bad is the amount of cholesterol it contains, too much of which can contribute to heart attacks and strokes.

The other type of fat, unsaturated, comes mainly from plant sources and is liquid at room temperature. Examples include sunflower oil, olive oil, fish, and nuts.

Given the uses that fat has in the body, very little, which can come with a very low-calorie, low-fat diet, obviously has consequences. These include not being able to absorb and store certain vitamins, less healthy hair and skin, and an effect on nerve cells.

Basically the opposite of all the benefits I just told you about.

Leave a Reply