A ketogenic diet is a high fat, low carb diet. Picture: Supplied
Google searches indicate celebrities like Kourtney Kardashian and Halle Berry swear by the keto diet.

The diet was conceived in the 1920s as a way to prevent seizures in epileptic patients.

So what is the keto diet, and why has it become so popular?

Zelda Ackerman, a registered dietitian and spokesperson for Association for Dietetics in South Africa (ADSA), said: “A ketogenic diet is a high fat, low carb diet.”

She said typically 80% to 90% of the energy from the keto-approved foods comes from fat and 10-20% from protein and carbs.

On a ketogenic diet, you may not eat more than 50g carbs a day.

The keto diet has been used to treat epilepsy and in the past 10 years has gained popularity as a treatment for Type 2 diabetes and insulin resistance.

Dr Andreas Eenfeldt, a Swedish doctor specialising in low carbohydrate, high fat dietary advice, said on a ketogenic diet, your body switches its fuel supply from sugars mostly on fat, burning fat 24/7.

“When insulin levels become very low, fat burning can increase dramatically. It becomes easier to access your fat stores to burn them off. This is great if you’re trying to lose weight, but there are also other less obvious benefits, such as less hunger and a steady supply of energy. This may help keep you alert and focused,” said Eenfeldt.

Ackerman said fatty acids are converted to ketone bodies - the only fuel other than glucose that can be used by the brain.

After three to seven days on the diet, the body starts to go into ketosis.

It may take up to a month to reach full ketosis.

In this diet you are allowed to eat:

  • Fats such as avocado, cream, butter, oil, fatty bacon, nuts.
  • Berries in small amounts.
  • Low-carb vegetables like lettuce, tomato, cucumber, green beans, broccoli, cauliflower, gem squash, mushrooms, onions, peppers, baby marrow, patty pans, cabbage and Brussels sprouts.
  • For protein, fatty meat, chicken, fish, cheese and eggs in moderation.

Ackerman said in the first few days you will probably not feel well while your body adjusts and goes into ketosis.

“People often report headaches, feeling tired and sick, muscle weakness, insomnia and having ‘brain fog’.

“If you deviate from the ketogenic diet by eating a lot of carbs or drinking alcoholic drinks like beer or ciders on occasion, your body will go out of ketosis and you’ll experience the same bad symptoms as in the first few days.

“So this is not the diet for you if you plan to ‘cheat’ or if you aren’t willing to limit alcoholic drinks.”

When you go into ketosis you will have bad breath. This is due to the ketone body acetone. You’ll need to brush your teeth several times a day or use sugar-free gum to help alleviate the bad breath.

The diet is low in fibre so you may become constipated.

You can easily develop nutritional deficiencies and will have to take supplements daily.

“If your body can’t digest fat well, you may experience diarrhoea. If you experience greyish, smelly stools that float, it’s best to choose an alternative diet strategy,” said Ackerman.

A ketogenic diet for weight loss is not the same as a ketogenic diet used to treat epilepsy in children.

Before making any changes to your child’s diet, consult a paediatric dietitian.