Fast 800: Dr Michael Mosley on his new rapid weight loss diet

Photo by Dose Juice on Unsplash Intermittent fasting is currently one of the most talked about eating regimes, thanks in part to Dr Michael Mosley. Six years ago he published the 5.2, a diet under which you rapidly reduce your calorie intake to just 500-600 calories per day on two ‘fasting’ days and eat normally for the other five. It became very popular.

Mosley has just published a new rapid weight loss programme, Fast 800 (Short Books, £8.99), so we caught up with him for the launch to find out how it differs to his previous plans. Part 1: 800 calories per day for at least two weeks

The Fast 800 is a three-pronged attack for weight loss. In the initial stage you eat only 800 calories each day for at least two weeks (in some cases longer), he explains, depending on how much weight you want to lose. This time, alongside his book, Mosley has also created the Fast 800 digital lifestyle programme (£99), a 12-week online support plan which allows people to tailor the approach to their goals and gives them access to a forum of health professionals who offer coaching and advice. Read more "I now recommend eating 800 calories based on a number of recent studies which have discovered people find it easier to follow, but they still get the same metabolic and weight loss advantages [as eating 500-600]," Mosley told the Standard .

"For a long time we believed that rapid weight loss was a terrible way to go, but the evidence is mounting of its benefits, if done properly," he continued, and by this, he says he means ensuring you have adequate amounts of protein, fibre and essential nutrients in your diet.

"Rapid weight loss is very motivating and long-term studies suggest it’s the amount of weight that you lose in the first month or so that predicts the long-term success of losing a lot of weight," he added.

And Mosley points to research conducted by Professor Roy Taylor and Dr Susan Jebb of Oxford University , which, he says, suggests that this low-calorie approach is a safe and effective means for rapid weight loss. The Mediterranean diet

Throughout all stages of Fast 800, you are advised to follow a lower-carb Mediterranean diet rich in fish, nuts, olive oil, fresh fruit and veg and low in red meat, refined sugar and saturated fat. At the start of 2019 US News & World Report named this regime, the best diet to follow for the second year in a row, having evaluated the health benefits of over 40 eating regimes using a panel of experts, including nutritionists, dieticians, and heart health and weight loss specialists. Time restricted eating

Mosley also recommends that you introduce time restricted eating under Fast 800, whereby you extend your overnight fast by several hours by having either an earlier dinner or a later breakfast (or both).

"Start by having a go at 12 hours (for your overnight fast), then try 14 hours," he said. "Some people have extended it to 16, but that’s pretty tough. I don’t necessarily recommend it but it’s become popular."

The 16:8 , where you have a 16-hour fasting period and eight-hour window for eating, is a popular fasting method, but Mosley argues the 14:10 is more sustainable. Part 2: Back to the 5:2

Once you’ve completed the initial rapid weight loss phase of the plan, you start following a 5:2 pattern, under which you have two days a week when you eat only 800 calories a day, and eat normally for the remainder.

Mosley says one of the biggest misconceptions about intermittent fasting is that you’ll get starving hungry, "For most people the hunger goes between 2-3 days of starting," he says.

The idea that your body will go into starvation mode and crash your metabolism (and stop burning fat) is also a "popular myth," he says. "In more recent studies on intermittent fasting, on entering a metabolic chamber the first reaction is that a respondent’s metabolic rate actually goes up.

"Obviously after a while, when your weight drops you’re going to be burning less calories when you’re 12 stone than when you’re 16 stone, for example, it’s the equivalent of carrying large suitcase around or not," he continued.

"This rapid weight loss approach is broadly a ketogenic approach, because you’re going to be burning fat and the way you do that is by producing ketones, that suppresses appetite but it also seems to preserve muscle mass." Part 3: Aim to maintain

In the final phase – the maintenance period – you’re no longer calorie counting but you continue to follow a Mediterranean diet, upping your wholegrain intake and increasing your activity.

Mosley invented the 5:2 diet after discovering he had Type 2 diabetes himself seven years ago, he lost 22 pounds following the regime and reversed his condition. "My blood sugar has been back to normal ever since," he said.

He highlights the results of Professor Taylor’s 12-week DiRECT (Diabetes Remission Clinical Trial) trial , which was published in the Lancet in December 2017. It involved 298 participants who had been previously diagnosed with Type 2 diabetes, half of whom received standard diabetes care from their GP, the other half of whom followed a diet of 800 calories a day for three to five months. Almost half of patients following the low calorie diet were able to reverse their diabetes. Remission was found to be closely related to weight loss. Over half (57 per cent) of those who lost 10-15kg were able to stop their medication, along with a third (34 per cent) of those who lost 5-10kg. Meanwhile, only 4 per cent of the control group achieved remission.

"Just before Christmas the NHS announced that they were going to trial 1,000 people using the 800 calorie diet," Mosley said. "It’s the first really good news about Type 2 diabetes we’ve had, that you can take control over your fate."

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