We’ve all got that friend who’s done the keto diet and is half the size they were, glowing and extolling its virtues to anyone who will listen. So what is this seemingly miraculous weight loss phenomenon, and should you try it?

First things first, what is the keto diet? According to the New Zealand Nutrition Foundation, it’s an “established strategy used by doctors to manage infants and children with epilepsy” but in recent years it’s also become popular as a quick way to drop some kilos by restricting carb intake; weight loss is rapid, and therefore motivated to continue. It still involves a calorie deficit, but the way that total is made up involves different food groups – essentially high-fat, moderate protein, and very low carbohydrate. This puts your body into ketosis, which switches it from burning carbohydrates to burning fat for energy.

So what’s in and what’s out? It’s a complicated equation but essentially things like bread, rice, starchy vegetables and sugar are largely out, fruit is limited to occasional berries but meat, fish, eggs and veggies that grow above the ground are largely fine – there are lots of apps and books around to make it easier to know the carb levels of different foods and other technical details (initially many people try to restrict their intake to just 20g a day). It can be quite healthy if done right – salads, stir-fries, and plenty of healthy fats all fall within the regime, and there has been some evidence that it could be beneficial for the management of blood sugar in type 2 diabetes patients (although there are risks so it should never be undertaken without medical guidance). But where it can be less healthy is if people forget the green veggie and good nutrition part and just load themselves with bacon, cheese, steak eggs and artificial sweetener-laden drinks and treats. Like every diet, there are personal choices.

So how do you know if it’s for you? Like any weight loss regime, keto will work amazingly for some people and not for others. It all comes down to your personality type and genetic makeup and whether those match a low-carb diet. Some will thrive and be able to adopt it as a new way of life, while others will find it harder to sustain. The only way to find out is to give it a go and see what your DNA thinks.