In 2020, Michael Mosley did something out of character: he started eating junk food. Mosley is a UK-based science communicator who has authored a shelf-load of weight-loss books, starting about a decade ago with The Fast Diet, which introduced the wider world to the concept of intermittent fasting.
Since then, he has written about diets to control blood sugar, improve gut health and shed fat faster – so for him to be tucking into burgers and chips, fried chicken, frozen pizza and fizzy drinks seems at the very least hypocritical. But, there is a reasonable explanation. The British-doctor-turned broadcaster is fond of self-experiments, and had put himself on what he describes as a “medium-level, ultra-processed food diet” for a documentary called Australia’s Health Revolution.
Initially, he rather enjoyed the novelty of unhealthy eating. “It took me back to the foods of my adolescence,” says Mosley. “And I quite liked eating things I hadn’t tried for a long while. But I didn’t like the way it made me feel. I was hungry all the time, sleeping badly and snoring loudly. It had an impact on my mood; I got a bit depressed and in a matter of days felt more lethargic.”
His GP wife, Clare Bailey, is normally tolerant of Mosley’s self-experiments, even coping with the episode when he swallowed a tapeworm to see how it would affect his body, but after two weeks she called time on this one. By then he had gained three kilos, pushed his blood sugar into the diabetic range, and his blood pressure was raised.
There is a happy ending to this misadventure. Mosley cut out the junk food, put himself on the diet he describes in his latest book, The Fast 800 Keto, and within 10 days had shed the extra kilos and everything was back to normal.
There is nothing new about the ketogenic diet. A low-carb, high-fat, adequate-protein way of eating, it has been used since the 1920s to help control seizures in children with hard-to-treat epilepsy. Decades later, a version known as the Atkins diet took hold, and more recently celebrities such as Kourtney Kardashian have helped keto go mainstream.
Mosley admits he has always been a keto sceptic, but has now changed his mind. “So many more studies have shown a benefit, at least in the short term,” he says. “I’m still not convinced that for most people keto is healthy in the long term. I’m sticking to the Mediterranean diet for that. But it’s like playing golf; you don’t use the same club all the way round. You start with your driver, you use your iron, you use your putter, depending on what stage you’re at and what you want to achieve.”
The new book includes a selection of recipes based on minimally processed foods. Although obesity rates have soared since the 1980s and one by one different macronutrients have taken the blame – too much fat, too many carbs, too much sugar – Mosley believes we are missing the bigger picture. He sees ultra-processed convenience foods – the things he was living on during his self-experiment – as the leading culprit.
The increase in the consumption of these factory foods has been matched by soaring obesity statistics. Now science is starting to make a much stronger case against them. Mosley cites one 2019 Spanish study published in medical trade journal the BMJ, involving nearly 20,000 university graduates who were followed for more than a decade. Those eating more than four servings a day of ultra-processed food were 62% more likely to have died during that time.
Meanwhile, US researcher Kevin Hall has conducted a trial that suggests consuming lots of ultra-processed foods leads to people overeating. He took 20 healthy participants and had them spend four weeks at the National Institutes of Health facility where they could be closely monitored. Each was restricted to a minimally processed or ultra-processed diet for two weeks, then switched to the other diet for two weeks (the study used a food classification system called NOVA, see panel, left). In both diets, the sugar, sodium, fat and fibre were exactly matched, but participants were allowed to choose how much they ate. By the second week on the ultra-processed diet, people were consuming an extra 500 calories a day, which resulted in a weight gain of about a kilogram, as opposed to a loss of about a kilogram when they were eating the minimally processed foods.
In the surveys they completed, participants claimed they weren’t deriving any more enjoyment from factory foods, but they did eat them faster, leading researchers to wonder if the fact they tend to be softer and easier to chew and swallow was to blame.
The other theory is called the “protein leverage hypothesis” and was developed by two professors at the University of Sydney, David Raubenheimer and Stephen Simpson. They studied the eating habits of animals and discovered they have a dominant appetite for protein.
When animals are given low-protein, high-carb foods, they will keep on eating them until they have been supplied with enough protein, gaining weight as a result.
Since protein is expensive, most industrialised foods tend to be lower in it and bulked up with fat and sugar instead, and this is now thought to have been a major driver of the obesity epidemic.
“What they do is make foods that taste like they’ve got protein,” explains Mosley. “We eat beef -flavoured crisps and are made to feel like we’re having protein, but we’re not – just carbs and fat – and so we overeat trying to satisfy our protein appetite.”
In his new book, Mosley is outspoken about the need for governments to intervene with legislation to control Big Food in the same way they have Big Tobacco.
“If you are going to change people’s health, there will have to be policy changes,” he says. “People were never going to give up smoking without governments making it really hard to smoke, and banning advertising.”
He believes the way forward is to tax unhealthy foods, subsidise healthier alternatives, and reduce or ban advertising of junk food, particularly to kids.
In New Zealand, where we have the third-highest obesity rates in the OECD, a new study from the University of Otago has shown that children are exposed to almost a brand a minute from when they wake to falling asleep at night. The research was conducted by attaching body-cams to 90 children, which captured images every seven seconds. Researchers concluded that New Zealand children are being saturated with marketing promoting harmful products, including junk food.
Another recent study, this time from the University of Chicago, reveals that this goes much further than conventional advertising. Social media also plays a significant role. Researchers analysed the nutritional quality of foods and beverages shown in Instagram posts from 181 highly followed famous names. They found that almost 90% of the 5180 posts were unhealthy enough to fail youth advertising standards.
As well as being widely promoted, ultra-processed foods are accessible. For many of us an unhealthy takeaway is just a tap of the smartphone away.
“I was filming in the East End of London recently and every 30 seconds we saw these mopeds going past with people delivering pizza,” says Mosley. “That is apparently the fastest-growing area of the food industry, junk food delivered to your house in less than 30 minutes. Part of me despairs, but there’s also a part of me that thinks this can’t go on. There is a point at which governments are going to have to act. Covid has demonstrated that [the virus has been more severe in those who are very overweight, even if they are young].”
Keeping it off
The UK has already introduced a sugar tax on manufacturers of soft drinks, which hasn’t affected sales but has resulted in the reduction of sugar content in some drinks. And there is talk of new regulations to ban junk-food advertising before 9pm.
While obesity rates continue to rise, Mosley continues to evolve his weight-loss programme, following the science and incorporating new developments to help people better succeed at losing excess weight and keeping it off. The online programme of his Fast 800 diet has been independently audited by the National Institute for Health Research in the UK and found to be particularly effective in those who have a body mass index (BMI) over 30 (considered obese).
“They lost an average of 8.7kg and maintained it for a year,” says Mosley. “About half of those who were Type 2 diabetics were able to get their blood sugar back to normal while on reduced medication, and with pre-diabetics it was about two-thirds, so that was very encouraging.”
His latest plan combines a low-calorie Mediterranean-style diet with low-carb ketogenic principles, and also incorporates intermittent fasting. This sounds complicated, but Mosley assures me it isn’t.
“It’s a simple three-step process. You start with a rapid weight loss, 800-calorie, keto-based diet, where you maintain your protein; that is very important. The next stage involves intermittent fasting. And then you switch over to the Mediterranean diet. Broadly speaking, the food that you are eating is not that different from beginning to end; all that is happening is you are adding in more carbs as you go along.”
The ketogenic diet works by depriving your body of the glucose it uses for energy. Once you deplete the sugar that is stored as glycogen primarily in your liver and muscles, the body has to tap into its energy reserve of body fat. So, while you are not eating carbohydrates – which the body breaks down and converts into glycogen – it starts burning fat fast. It does this by converting fatty acids into chemicals called ketone bodies, which it uses as fuel. Mosley compares this to being like a hybrid car switching from relying on electricity to using petrol.
This is not necessarily a comfortable process, at least at first. Some people suffer “keto flu” with fatigue, headaches and brain fog. Constipation can be a problem. And as you go into ketosis your breath may smell like nail polish remover.
“Then, suddenly you start to feel completely different,” Mosley promises. “As you switch into major ketone-producing, fat-burning mode your energy levels soar and your mood lifts. It really does feel as though you’ve found another gear.”
Ketogenic diets have been controversial, because some versions involve consuming a lot of saturated fats. However, Mosley’s approach has a greater emphasis on heart-healthy fats such as oily fish, avocado, nuts, seeds and olive oil. Also, the keto phase of the diet lasts for up to 12 weeks – during which he promises weight loss of 2kg a week – then, in stage two, a few more carbs are allowed for at least three days a week, so dieters move in and out of ketosis and weight loss slows.
The science is starting to stack up in favour of keto. Not only are studies showing it is an effective way for the overweight to shed kilos and improve their metabolic health, there is also evidence to suggest that it reduces inflammatory markers and can be helpful in pain management. A small pilot trial at the University of Sydney, which included people with a range of conditions including fibromyalgia and back pain, found that, as well as reduced pain, participants on the ketogenic diet also lost a significant amount of weight and had lower anxiety and depression than those who were on a whole-food (unprocessed) diet.
Ketones appear to work as signalling molecules, modulating the brain, damping down hypersensitive nervous systems and blocking inflammatory pathways – hence their contribution to seizure control in epileptics.
“We know that when you produce more ketones, this leads to production in the brain of something called BDNF – brain-derived neurotrophic factor – and this seems to be important for stabilising and maintaining brain cells,” says Mosley. “So keto appears to be significant for brain health, and there are preliminary studies looking at it not just for pain but also multiple sclerosis.”
The other criticism is that limiting food choices so drastically makes keto hard to stick to. Mosley argues that the higher protein content means this way of eating is actually more satiating as the body takes longer to break down protein.
He offers tips and tricks to staying on track, including using keto sticks to check the ketone levels in your urine, which he himself found enormously motivating. “It is genuinely exciting seeing the strips change colour, and a surprisingly useful deterrent if you’re tempted by a biscuit,” he promises.
The hunger hormone
There are studies to show that the ketogenic diet helps with appetite control by suppressing the increase in the hunger hormone ghrelin, which normally takes place when you cut calories. And, the other advantage, says Mosley, is that it doesn’t seem to slow the metabolic rate.
Trying out the diet himself was something of a revelation but, although he saw results fast, those who have had type 2 diabetes and/or high blood pressure for longer will have to give it more time to see meaningful results.
“The best time to lose weight is just after you put it on,” Mosley says. “So, if you gained a lot of weight over the Christmas holidays, now is the time to act before your body gets used to it.”
Self-experiments aside, eating well remains an ongoing struggle for him. He has a sweet tooth and, unlike his wife Clare, is not naturally slim. But Mosley does have an apparently insatiable appetite for scientific research and is prepared for his beliefs about diet to be shaped and reshaped as researchers learn more about the impact of food choices on the body.
“I’m obsessed with how to improve mood, sleep and metabolic health, and find better ways to lose weight and keep it off,” he says.
“And the science behind diets and dieting is constantly evolving. There’s lots of interesting research popping up all over the place – it’s hard to keep up with it.”
Most foods are processed to some extent. Very few of us are churning our own butter or pressing our own olive oil, or even baking our own bread. The NOVA Food Classification was designed by scientists at the University of São Paulo in Brazil to help identify how processed any food is.
Minimally processed foods may have been ground, dried, fermented, frozen, pasteurised and packaged but no oils, fat, sugar, salt or other substances have been added – examples include oats, wheat, couscous, legumes and unsweetened yogurt.
Processed foods are natural but may have had small amounts of other substances added, such as salt, sugar and oil. Most have two or three ingredients. Examples include tinned fish, tomato paste, pickled vegetables, cured meats and freshly made bread.
Ultra-processed foods are industrial formulations, made from substances extracted from foods, synthesised in laboratories, packed with additives like colours, stabilisers and flavour enhancers, as well as lots of sugars, fats or salt, and using a variety of manufacturing techniques. Ultra-processed foods are designed to be highly profitable (low-cost ingredients, long shelf-life), convenient, hyper-palatable products. They contain substances never or rarely used in kitchens (such as high-fructose corn syrup and hydrolysed proteins). Examples include fizzy drinks, powdered soups and sauces, packaged baked goods, margarines and spreads.
Low-carb comfort foods
This classic dish is one of our favourite comfort foods and, like many of these recipes, works well for the whole family.
Tarragon Chicken with Bacon and Mushrooms
- 2 chicken thighs, bone in, skin on and trimmed
- salt and pepper
- 1 tbsp olive oil
- 2 rashers smoked back bacon, diced
- 150g swiss brown or white mushrooms, sliced
- 1 garlic clove, peeled and finely chopped
- 1 tsp dried tarragon
- 3 tbsp crème fraîche
- 1 tbsp cider vinegar
Preheat the oven to 200°C/fan 180°C. Season the skin of the chicken with salt and freshly ground black pepper, drizzle over half the olive oil and roast in the oven for 30-35 minutes, or until the juices run clear when pierced with a knife.
Meanwhile, heat the remaining oil in a frying pan and fry the bacon and mushrooms for 2-3 minutes, or until lightly browned. Add the garlic and tarragon and fry for 1 minute more.
Just before the chicken is ready, remove the frying pan from the heat and stir through the crème fraîche and vinegar. Season to taste with salt and freshly ground black pepper.
Serve the sauce with the chicken on top and plenty of steamed greens.
NON-FAST DAY: Increase or double the portion size and/or roast small cubes of butternut pumpkin alongside the chicken in step 2, or serve with 2-3 tablespoons of cooked puy lentils.
Prep time: 5-7 minutes
Cook time: 30-35 minutes
Per serving: 355kcals, 32g protein, 1g carbs
There is something indulgent about a pizza, but the standard base is starchy and fattening. This dough uses protein-rich almonds instead of white flour and is much lighter. We suggest a tomato, chorizo, mozzarella and rocket topping, which is our family favourite, but you can be creative with your own variations.
Tomato, Chorizo and Mozzarella Pizza with Rocket
- 140g ground almonds
- 60g psyllium husk
- 1 tsp baking powder
- 1 tsp fine sea salt
- 2 egg whites
- 200ml warm water
- 50ml olive oil
- 2 tsp cider vinegar
FOR THE TOPPING
- 1 tbsp tomato purée
- 15g chorizo, diced
- ¼ ball mozzarella
- salt and pepper
- torn rocket to serve
Preheat the oven to 200°C/fan 180°C. Mix all the dry ingredients together in a bowl. Add the egg whites, warm water, olive oil and cider vinegar and give it all a quick mix until well combined. It should form a dough-like ball.
With a few drops of olive oil on your hands to prevent sticking, divide the mixture into 5 balls. Place one ball on a piece of non-stick baking paper and put another piece of baking paper on top.
Press down with your hands, then use a rolling pin to roll out the base until it is 1-2mm thick. Repeat with the remaining balls or store them in the fridge or freezer for another day. Transfer the non-stick baking paper to a baking sheet. Spread with the tomato purée, then scatter the chorizo and mozzarella over the top.
Season with salt and freshly ground black pepper. Bake for 15 minutes, or until the pizza is just crispy and golden brown around the edges. As soon as it is out of the oven, scatter with rocket. Fill half your plate with salad.
Makes 5 pizza bases/topping for 1 pizza
Prep time: 15 minutes
Cook time: 15 minutes
Dough per serving: 313kcals, 9.6g protein, 12g carbs
Topping per serving: 160kcals, 12g protein, 2g carbs
Recipes from The Fast 800 Keto, by Dr Michael Mosley (Hachette, $37.99)
This feature was first published in the February 5, 2022 issue of the Listener.