Diet & Nutrition

Everything you need to know about the ketogenic diet

Is the new low carb diet plan right for you? An expert weighs in.

Ketogenic dieting: the low carb diet that celebrities like Gwyneth Paltrow, Kim Kardashian-West and Megan Fox have all pledged themselves to.

However, like with many diets, we’re always left questioning whether they actually work or not.

Like, why follow a ketogenic diet? Or keto diet for short. Who should eat a keto diet? And in terms of a low carbohydrate diet, is this really the best way to lose weight?.

Here, Dr Alan W Barclay, consultant dietitian, nutritionist and co-author of The Good Carbs Cookbook, answers all your questions to see if this diet is, in fact, any good for you.

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What is the ketogenic diet?

A ketogenic eating pattern is very low in carbohydrates and moderate in protein, meaning a high percentage of total energy (kilojoule) intake comes from fat.

As fat is the main source of energy being consumed, the body must then use this (that is, break it down) as its main energy source or ‘fuel’. When dietary fat is metabolised for energy, by-products called ketone bodies (molecules that are made by the liver from fatty acids) are produced which are used up by the body’s tissues, muscles and the brain. This process is known as ketosis.

The body can enter ketosis during times of severe energy restriction (such as during fasting or starvation) or prolonged intense exercise, or when carbohydrate intake is reduced to around 50g per day, or less – the equivalent of around two slices of bread, and a banana.

Short-term side effects of ketosis can include fatigue, bad breath, nausea, constipation and headaches.

How safe is ketogenic diet?

The most common side effects of the diet are vomiting, constipation and diarrhoea. While less common, other adverse effects include increased respiratory tract infections, pancreatitis, gallstones, fatty liver, high cholesterol, acidosis, dehydration, decreased bone density, extended hospital stay, hunger and abdominal pain.

It’s important to note that we only know medium term (less than two years) health effects and do not know what the long-term (greater than two years) health effects are.

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The ketogenic diet for weightloss

Following a keto diet will undoubtedly result in short-term weightloss, which probably comes down to a reduction in total energy (kilojoule) intake, the depletion of liver and muscle glycogen stores and associated water, and a reduced appetite (which is a side effect of metabolising ketones, and also due to satiety associated with eating foods containing fat and protein).

But the key to maintaining a healthy weight in the long-term is an eating pattern that is sustainable over time. With this in mind, dietary recommendations should always be tailored to an individual – as everyone is unique, and what works for one person, may not work for another. That is, there is no one-size-fits-all approach when it comes to achieving and maintaining a healthy weight.

Who benefits from ketogenic diet?

Children with severe epilepsy who have not responded to conventional therapy may wish to trial the diet under careful medical and dietetic supervision.

When ketogenic diet doesn’t work

If you don’t consume less than 10% of energy from carbohydrate, you won’t go into ketosis, so the diet won’t work. For an adult that means consuming no more than 50 g of carbohydrate per day, and for children it means less due to their typically lower energy requirements. For most people, this is very difficult.

The keto diet was used in the 1920s to help treat epilepsy sufferers, but is now an eating plan celebs like Kim Kardashian West and diet devotees alike have come to love.

3 things to consider before starting a ketogenic diet

1. You’ll be missing out on some seriously healthy foods

A ketogenic diet is based around a very low carb diet plan, which means nutritious foods like vegetables and fruit, wholegrains and dairy foods will need to be limited.

In fact, the 20-50g of carbohydrates allowed in a ketogenic diet is equivalent (in carbohydrate terms) to just a small tub of yoghurt, an apple, and half a medium potato over a day.

2. It might affect your gut health

As well as filling us up, fibre from fruit, vegetables, legumes and wholegrains is vital for a healthy gut – such as to support the growth of ‘good’ bacteria and to keep the lining of the bowel healthy.

On average, we eat only half the recommended daily amounts of at least 25g of fibre for women and 30g for men – and being on a ketogenic diet will make it harder to meet these targets.

3. You may find it hard to stick with

The best ‘diet’ is one that ticks off all your nutritional needs, fits with your lifestyle, and that you enjoy. If you get these right – you’re onto a winner over the long haul!

Many studies show those on a ketogenic diet find it difficult to sustain, due to its restrictive nature (which can also make family meal times and outings with friends more complicated).

Before you consider changing your diet or eating plan, be sure to speak to your GP and a dietitian or nutritionist first.

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