What is a ketogenic diet?

A ketogenic diet is a very low carbohydrate diet that keeps blood glucose levels down and helps to reduce weight.

The diet also has other therapeutic benefits for people who have metabolic conditions and can improve the control of seizures.

The diet was first devised back in 1921 by endocrinologist Dr. Geyelin, to help prevent seizures in epilepsy patients. The diet was strict, a 4:1 ratio of fats to proteins and carbohydrates, he noted it produced a huge reduction in inflammation in the digestive system, a major cause of epilepsy.

When it comes to obesity, many of the interventions such as bariatric surgery or those focused on reducing dietary fat have been shown to fail in the long term. However, there have been a number of studies that have shown the ketogenic diet to be successful particularly in the overweight, diabetic population.

How does a ketogenic diet work?

The diet is classified as eating 30g or less of carbohydrates per day. Consuming low levels of carbohydrates inspires the body to gather its energy from burning fat resulting in the circulation of ketones.

Ketones are a type of acid in the body that become elevated after periods of starvation including after a night’s sleep or when the body has an insufficient supply of insulin. It is normal for us to have ketones circulating in our body as they are produced when fat is burned. Thus, ketones are intentionally elevated when a ketogenic diet is consumed.

The Rising Popularity of The Ketogenic Diet

We live in a time where fad diets and exercise regimes are continuously on the rise. The millennial generation has adopted and promoted a healthy lifestyle, even branded as being obsessed with health.

This generation isn’t as interested in the mainstream of the health industry like the generations before it, instead focussing on holistic or alternative approaches that fit around their busy everyday lives.

The ketogenic diet is no different. Yes, it has its health purposes for conditions, but the diet goes beyond that too. In fact, earlier this year it was thought to become the next go-to weight loss diet.

What Are the Benefits of The Ketogenic Diet?

The ketogenic diet is not only ideal for weight loss but has been shown to have major health benefits for many medical conditions. There are some conditions that have a sound evidence base such as epilepsy, diabetes, and obesity whereas the ketogenic diet for cancer and neurological disease is an emerging area of study.

The biggest benefits of the ketogenic diet are:

  • Reduces blood glucose levels
  • Improves mental performance
  • Reduces triglycerides
  • Increases the good cholesterol circulating in our bodies which in turn reduces bad cholesterol

The diet does this by increasing the amount of good fat we eat such as nuts and cutting out bad examples of carbohydrates such as white bread, pasta, and sugar. By eating larger amounts of ‘good’ fats, it is thought our desire to eat is reduced, so fewer calories are consumed.

The Disadvantages of The Ketogenic Diet

As with most things in life, the ketogenic diet is not perfect and for this reason may not be suitable for everybody.


One side effect which can affect people who are just starting out on the ketogenic diet is keto-flu.

When you switch to this type of diet, the body has to adjust from using glucose as its main energy source to using ketones instead. This process of keto-adaptation can last for anything up to four weeks. Generally, the symptoms don’t last quite this long and tend to disappear on their own.

By the end of the first week on the ketogenic diet you may begin to feel some or all of the following symptoms:

  • Slower mental ability
  • Dizziness
  • Tiredness
  • Food cravings
  • Faster heart beat when you lie down
  • Not being able to sleep

One way to try to avoid keto-flu is to slowly introduce your body to the diet. So, rather than just cutting down your carbohydrate intake completely in one go, you may feel better if you do this gradually over several weeks.

Loss of Salt

As the body switches from glucose to ketones as its source of fuel, glycogen the body's stored energy source, is used up, releasing water into the bloodstream. The excess water is then excreted in our urine and as a result the salts in our body can be reduced too.

Therefore, it is important to stay hydrated by drinking plenty of water throughout the day. It is also vital to keep your salt levels up as this can prevent side effects such as headaches and lightheadedness. Other salts such as magnesium and potassium are important for our bodies to function correctly. However, having a lack of salt shouldn’t be anything to worry about as long as you are eating healthy, natural foods including:

  • Nuts
  • Fruit
  • Vegetables
  • Fish
  • Meat
  • Dairy products.

Bad Breath

When the fat burning stage is reached, ketones can be released in our breath which can cause bad breath or halitosis. One form of ketone is acetone which can be released in our breath resulting in a metallic taste in our mouths.

Using mint gum or breath freshener can help to cover the smell of bad breath. Or you may prefer to brush your teeth and use mouthwash more frequently throughout the day.

Food Choices

Perhaps, one of the major drawbacks of the ketogenic diet is the foods it makes you cut back on. For example, the diet is designed to cut down on carbohydrates such as:

  • White bread
  • Pasta
  • Sugar
  • Grains

Typically, these are our comfort foods and so by following a ketogenic diet, foods like these will be great decreased.

Other side effects of consuming a ketogenic diet can include:

  • Vomiting
  • Constipation
  • Diarrhoea
  • Kidney stones
  • Increased bruising to skin
  • Risk of fractured bones
  • Lower growth rate in children


Overall, the ketogenic diet is a low carb diet which essentially turns the body into a fat-burning machine, making it a good diet for people who are overweight, diabetic or epileptic. The celebrity craze has also influenced others to follow the diet as part of their everyday lifestyle, cutting out carbs to lower insulin, glucose, and LDL cholesterol levels.

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