Should I be following a ketogenic diet? A dietitian weighs in

  • The ketogenic diet is a popular diet that focuses on large amounts of fat.
  • Possible health benefits have been discussed at length.
  • While there are great success stories, this diet is not suitable for everyone.


The ketogenic diet has recently become one of the most popular fad diets. It has captured the interest of many people in search of a weight loss solution. And, there is no shortage of reported success stories. 

Despite the recent hype, the ketogenic diet is not new and was originally used in the 1960s in children who suffered from epilepsy. There is good evidence showing that a ketogenic diet reduces seizures in children, in some cases as effectively as medication.

This, however, needs to be done under medical supervision with the support of dietitians. Because of neuroprotective effects, questions have been raised about the possible benefits for other brain disorders, such as Parkinson's disease, Alzheimer's disease, multiple sclerosis, sleep disorders and autism.

To date, there are no human studies that support using ketosis to treat these conditions.

What exactly is the ketogenic diet?

The diet calls for the consumption of large amounts of fat, a moderate amount of protein and a very small amount of carbohydrates (< than 50 g/ day). As a percentage of daily calories, the nutrient split amounts to fat at 75–80%, protein at 15–20% and carbohydrates at 5%. This differs from the nutrient split of a nutritionally balanced calorie-restricted diet, which is 40–45% carbohydrates, 20% protein and 30–35% fat. 

When following the keto diet for about five days, due to the unavailability of carbohydrates, the body enters a state of ketosis, which means that it uses fat stores (instead of glucose) as a source of energy. There are several ketogenic supplements on the market that may contribute to reaching ketosis faster.

Keto-friendly foods include:

oils (e.g. olive oil, avocado oil, coconut oil); avocado; cream; butter; cream cheese; cheese; coconut; nuts; seeds; leafy green vegetables (e.g. spinach, kale, collards, romaine lettuce); non-starchy vegetables (e.g. zucchini, asparagus, cucumber, broccoli, cauliflower, bell peppers); meat (chicken, beef, pork, lamb); fish; eggs.

Non-keto-friendly foods include:

all processed foods; all sugar and sugar-containing foods, such as chocolates, sweets, pastries, sugary drinks; alcohol; milk; whole grains; all cereals; bread; rice; pasta; legumes (beans, peas, lentils); starchy vegetables (potato, sweet potato); and all fruit (except small portions of berries).

The ketogenic diet and weight loss

There is evidence of faster weight loss when following a ketogenic or exceptionally low carbohydrate diet, compared to a nutritionally balanced or Mediterranean diet. It is suggested that this is because of an increased feeling of fullness from eating a large amount of fat and protein. It is important to note that the observed differences in weight loss seem to disappear after two to three weeks. 

Research has found that in the long term (two to three months), the amount of weight lost by people following a ketogenic diet, was no more or less than the weight lost by people who followed a nutritionally balanced, energy-controlled diet. Evidence shows that there is no metabolic advantage when following this diet, but rather that weight loss results from an energy deficit, as is the case with all types of energy-controlled diets. You, therefore, do not have to push your body into a state of ketosis to achieve weight loss.

keto diet

The ketogenic diet and health risk

The ketogenic diet is not an easy diet to follow in the long term. In addition, there is evidence of an inadequate intake of some essential nutrients, as well as some health consequences when reducing carbohydrate intake too much and consuming excessive quantities of saturated fats. 

It is common for people starting the ketogenic diet to experience flu-like symptoms, such as headaches and fatigue. Also known as "keto flu", characterised by bad breath, frequent urination and a dry mouth. Other potential risks include kidney stones, liver problems and vitamin and mineral deficiencies, especially calcium, selenium, and zinc.

Decreased bone mineral density and gastrointestinal distress, such as bloating and constipation due to the lack of fibre in the diet, have also been reported. 

The high intake of saturated fat found in fatty cuts of red meat, chicken skin, cheese, butter, and cream, contributes to an increase of LDL (the “bad” cholesterol) that increases the risk of heart disease. Excessive intake of saturated fat can also contribute to inflammation in the gastrointestinal tract.  

People who should avoid the ketogenic diet

  • Those who have a history of eating disorders can trigger a relapse when following a strict diet that eliminates food groups. 
  • Someone who has had a gallbladder removal should also avoid a keto diet. A gallbladder stores bile, which aids in fat digestion. Without this organ, you will not feel your best on a high-fat diet.
  • The long-term safety of the keto diet for people who have multiple sclerosis is questionable and they should be cautious of side effects, such as fatigue and constipation.
  • People who have kidney and liver problems as well as people who have heart disease, high blood pressure and type 2 diabetes should avoid a keto diet.
  • Pregnant and breast-feeding women should also be cautious.

The question of carbs

The objective of all popular weight-reducing diets is to restrict energy (calories). Research has shown that the extreme manipulation of a food group, whether fat, protein or carbohydrate, is a poor tool to teach any individual healthy eating habits that are essential to keep the weight off. 

The good side of the ketogenic diet is the elimination of unhealthy sugars and refined (white flour) carbohydrates. Research, however, has firmly established that replacing them with excessive quantities of protein of animal origin and saturated fats is not the answer.

Replacing unhealthy carbohydrates with controlled quantities of whole grains, legumes, fish, and a variety of fresh vegetables and fruit (in controlled portions) with nuts, seeds and vegetable oils, has shown significant health benefits towards weight loss, the avoidance of chronic lifestyle diseases and longevity.

These foods provide the necessary fibre, which is essential for optimal gut health, immunity and a reduced risk of colon cancer. In addition, the phytonutrients, vitamins, minerals, plant protein and essential fatty acids have been proven to reduce metabolic processes, such as inflammation and oxidative stress.

To conclude

Although a ketogenic diet may initially cause an encouraging amount of weight loss, it will be better to consult a dietitian to assist you in formulating a nutritionally balanced diet, taking your lifestyle, food preferences, culture, and budget in consideration. More importantly, a dietitian can help you find strategies to change the eating and lifestyle habits that caused your weight gain in the first place and replace them with habits that can keep the weight off in a sustained manner.

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