Following a low-carb diet is much more practical.
A diet developed in the 1920s to treat children with epilepsy is suddenly all the rage. The ketogenic diet, or “keto diet”, has reportedly been endorsed by celebrities and even athletes are giving it a go.

The keto diet is one of a series of fashionable low-carb diets that include the Atkins diet, the South Beach diet and the Zone diet. There are hundreds of people selling keto diet plans online and on social media, with big promises of results. The diet got its name because ketones are the source of energy that the body uses when it’s burning fat. Ketones are produced in weight loss regardless of the type of diet you follow. Anyone losing weight is on a keto diet.

The production of ketones doesn’t necessarily mean you are burning body fat. So when keto dieters add fat to their diet through bulletproof coffee or coconut oil, it is burnt as fuel instead of body fat - which defeats the object of the diet, achieving weight loss.

By adding additional fat to the diet, your energy balance will remain positive regardless of the fuel (carbs, fat or protein) and this will promote weight gain, as is demonstrated by children on ketogenic diets when they gain weight despite the fact their urine shows that they are producing ketones.

Inducing ketosis - a natural state for the body, when it is almost completely fuelled by fat - in therapeutic diets is a skill that needs close supervision. This is because the diet is not balanced and can easily lead to nutrient deficiencies, nausea, vomiting, headache, tiredness, dizziness, insomnia, poor exercise tolerance and constipation - sometimes referred to as keto flu.

Most people calling their diet a keto diet are simply following a low or very low-carbohydrate diet. Low-carb diets can be helpful, at least in the short term, for some people to lose weight. However, as with the true ketogenic diet, most people can’t stick to a low-carb diet for long. The latest research shows it’s the ability to stick to the diet that matters. Hence, if a low-carb diet or keto diet works for you and you are able to maintain it for as long as it takes to lose excess body fat - and you’re meeting your nutritional requirements - then the science says that this should be encouraged.

For most people, following a low-carb diet, rather than a no-carb diet, is much more practical as it will also allow for the inclusion of fruit and all vegetables. This represents much better dietary balance and usually leads to people sticking with it for longer.

In the end it all comes down to taking. On average, people get about half of their energy from carbs, so by cutting out the source of half of your energy from your diet - even if some of that energy is replaced by fat - you are likely to reduce your energy intake, which leads to weight loss.

But if you can’t sustain the keto diet, don’t worry, you are in the majority. Try considering why you eat, rather than what you eat. Tackling convenience buying and emotional eating is the key.

lSophie Medlin is a lecturer in nutrition and dietetics at King’s College London