What is a keto diet?

The ketogenic or ‘keto’ diet is a strict low-carb, high-fat and moderate protein plan that sends the body into a state of 'ketosis'. This is when the body burns fat (in the form of ketones), instead of carbohydrates as its main fuel source.


If you're considering a keto diet, read up on our guide for all you need to know about keto and discover the best ketogenic food choices with our top 10 foods to try on a keto diet.

Myth 1: a keto diet is a high-protein diet

The keto diet is often thought to be a high-protein diet, but while there are moderate amounts of protein, most of the calories in a keto diet are derived from fat. This confusion may come from the fact that a keto diet permits the inclusion of high-protein foods like meat, fish, eggs and dairy. Although these foods are included, they shouldn’t make up the majority of your calories.

A keto diet requires:

  • about 70-75 per cent of calories to be derived from fat
  • 20-25 per cent from protein
  • and just 5-10 per cent from carbohydrates.

The word 'keto' spelled out in foods

Myth 2: keto is the same as low carb

Keto is not the same as low carb. For a keto diet, you’re talking about 20g of carbs per day (that’s equivalent to one small boiled potato) – perhaps 20-50g at a push, whereas low carb would be between 50-130g per day, although there is no official definition for a low-carb diet.

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In addition, a low-carb diet may be quite high in protein, but with keto it’s important to consume protein in moderation while keeping fat levels high. This is because the body converts protein to glucose, which may disrupt your ability to stay in ketosis and burn fat as your prime fuel.

Read more about low-carb diets.

Myth 3: a keto diet is the fastest way to lose weight

Although weight loss can be rapid at the outset (up to 10 pounds or 4.5kg in two weeks), research suggests that, in the longer term (after one year), the effect is the same as other weight loss approaches. Therefore, if weight loss is your goal, there are probably more joyful ways to go about it. Keto is primarily a therapeutic diet, with weight loss often being a side effect.

The initial weight loss is largely attributed to the diet’s diuretic effect. This initial water loss is likely to account for much of the change in weight and may be followed by fat loss. Longevity is key to weight management, and you’ll find that there are much easier paths to weight loss than keto.

Myth 4: keto is the natural way humans should eat

I don’t know exactly what cavemen were eating, but I think to refer to it as ‘keto’ would be misleading. Fasting is a natural way to bring the body into ketosis, so more likely our ancestors experienced quite a lot of this when food was scarce. Ketosis involves the production of ketones in the body, this process is natural and safe, as the body uses ketones as energy in times of scarcity.

However, during the summer months, it’s likely our cavemen ancestors consumed a lot of fruit, which would be high carb. Equally, after a successful hunt, a lot of meat may have been eaten, which would mean they enjoyed a meal that was relatively high in protein. Both of which suggest it was not a keto approach to eating.

A keto breakfast

Myth 5: you can eat as much fat as you want on a keto diet

It depends on your goal. If it’s weight loss, then excessive amounts of fat will add calorie density and may impede your results. At 9kcal per gram, fat is more calorie-rich than either carbs or protein, which both contribute 4kcal per gram. You should also consider the types of fat. While we do need saturated and unsaturated fats in our diets, too much of one type may have a negative impact on your health.

Myth 6: you’ll feel great on a keto diet

Some people experience unpleasant side effects when they adopt a keto diet, including light-headedness, fatigue, nausea, blood sugar swings, headaches and constipation. Together these symptoms are often referred to as 'keto flu'. Some followers experience these symptoms as a result of the body’s rapid excretion of fluids, and with it sodium, which happens in response to the diet’s severe restriction of carbs.

In need of some keto-friendly recipes? Have a look at our collections:

Keto breakfast recipes
Keto snack recipes
Keto lunch recipes
Keto dinner recipes

Enjoyed this? Now read…

What are high-protein diets?
What is the paleo diet?
What is a balanced diet for women?
Is a low-fat diet healthy?

This guide was reviewed on 10 June 2024 by Kerry Torrens.


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