The keto diet – what you need to know

Recently, the ketogenic diet (keto for short) has been in the spotlight as the new diet to try. With that dietitian, Retha Harmse, educates us on the ‘latest craze’ diet.


The keto diet is everywhere; it’s difficult to avoid seeing it on influencers’ Instagram stories; keto options in supermarkets and on restaurant menus; and even friends or relatives speaking about their wonderful results. But, let’s take a closer look at the ketogenic diet.

What it the keto diet?

The ketogenic diet is a high fat, low carbohydrate and low to moderate protein diet that changes the body’s metabolism into ketosis. Any diet where fat is metabolised instead of carbohydrate is essentially a ketogenic diet.

Understanding ketosis

During a ‘normal’ or well-balanced diet, the body’s main source of energy is carbohydrates. More specifically, glucose which is the end-product of carbohydrate metabolism/digestion.

But the body is also able to burn fat for energy, and this is utilised in the form of ketones. Ketones are molecules produced by our liver when fat is metabolised; this metabolic switch is called ketosis.

However, the body doesn’t go into ketosis if there is enough carbohydrates available. Consequently, carbohydrates need to be drastically reduced or eliminated to move towards ketones as the primary energy source.

What does it involve?

Generally, on the ketogenic diet, the macronutrient ratio varies within the following ranges:

  • 65 – 80% of calories from fat.
    • Fat-intake is often over 150 grams (double the usual intake of fat).
  • 20 – 25% of calories from protein.
  • 5 – 10% of calories from net carbohydrate.
    • Roughly 20 – 50 grams a day (compared to the recommended daily amount of 200 – 300 grams per day).

What does this mean in non-dietitian language?

The keto diet prescribes high amounts of fat (both animal and plant sources), low-carbohydrate vegetables, nuts, seeds, and modest protein in the form of meat, fish and eggs. It excludes grains, dairy, legumes, soy, most fruits and starchy vegetables.

Meticulous planning

Ketogenic diets require meticulous planning to ensure the liver continues producing a constant supply of ketones to supply the body with energy.

To maintain ketosis, an individual’s diet needs to be precisely planned and tracked daily, as limiting carbohydrates and increasing fat is not the only focus of the ketogenic diet.

It’s also imperative not to consume protein in excess, as proteins can also be broken down to glucose (through a process called gluconeogenesis). This will in turn inhibit the ability for the body to move into ketosis. Also, if carbohydrates are not restricted enough, it might result in ketonuria (ketones in the urine and not used as energy). This is detectable by urinary dipstick analysis.

The history of keto diets

Although ketogenic diets might seem like the new ‘craze’; they are nothing new. Ketogenic diets have been around from the early 1900s, when they were discovered to have an efficacy in the treatment and management of epilepsy in children.

It is still used for this purpose; although more recently these diets have gained popularity for the management of obesity and Type 2 diabetes.

However, it’s important to note that the macronutrient ratios and recommendations for the ketogenic diet in the management of paediatric epilepsy are substantially different than those advocated for the management of obesity and Type 2 diabetes.

What are the benefits?

In terms of weight loss, evidence suggests quicker initial weight loss. This might be due to the initial use of glycogen stores (glucose stored in the muscle and liver), or reduced energy intake due to increased satiety from eating a large amount of fat and protein.

But long-term differences in weight lost showed no significant difference in comparison to other diets.

As mentioned previously, ketogenic diets have been used for decades to treat epilepsy. But, more recently, research has suggested that they might have a role in treating Type 2 diabetes and inflammatory conditions, such as chronic pain. That been said, there isn’t sufficient evidence just yet to support ketogenic diets for these conditions in terms of its long-term safety and efficacy.

Lastly, research has found that people consuming fewer calories from carbohydrate tend to eat fewer foods high in added sugars, such as soft drinks, doughnuts, etc. Yet, other research has found that the more carbohydrate consumption is restricted, the greater risk there is for poor nutrient intake. 

Potential side effects

  • High fat diets, especially when it’s high in saturated fat, increases total cholesterol. More specifically LDL cholesterol which is the “bad” cholesterol.
    • Both total and LDL cholesterol are both biomarkers for poor cardiovascular health.
  • Reduced energy and decrease in performance in activities that use short bursts of power, because ketogenic diets depletes the energy stores in your muscles (glycogen as mentioned previously).
  • Fatigue, general weakness, headaches and sluggishness, or brain fog.
  • Due to the very low fibre intake of ketogenic diets, you may experience constipation, increased risk of digestive problems and microbiota imbalances.
  • Limited fruit, vegetables and grains consumption – thereby limiting nutrient intake that might lead to deficiencies.
    • Nutrients (lack of) of particular concern on the ketogenic diet are calcium, vitamin D, selenium, magnesium, zinc and phosphorus.
  • Increased oxidation and inflammation in the body.
    • Recent evidence has shown that high fat diets, especially saturated fat, may promote inflammation and lead to the progression of inflammatory diseases, such as Alzheimer’s disease.
  • Possible loss of lean muscle mass.
  • Dry mouth, frequent urination, halitosis (bad breath = acidic, fruity odour).

Take-home message

Currently, there is a lack of strong evidence for ketogenic diets, based on their health claims about longevity, gut microbiome and heart health. Diets that are higher in carbohydrates and lower in protein, in fact, have the strongest links to longer lives and happy guts.

There are various probable side effects when following a ketogenic diet, which is why there is a need for ongoing monitoring and consistent assessment by a qualified dietitian.

Overall, unless medically indicated, I do not recommend following a ketogenic diet. Considering fat and carbohydrates, it’s all about balance.

  • The types of fat you include and the quantities you consume does matter.
  • Carbohydrates does form part of a healthy balanced diet.

My tactic is always to look at sustainable changes you can make that doesn’t include elimination of entire food groups.

MEET OUR EXPERT


Retha Harmse (née Booyens) is a registered dietitian and the ADSA public relations portfolio holder. She has a passion for informing and equipping the field of nutrition. She is currently in private practice in Saxonwold, Houghton, and believes that everyone deserves happiness and health. To achieve this, she gives practical and individual-specific advice, guidelines and diets.


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