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‘Lose a Stone in 21 Days with Michael Mosley’: Second Nature’s response

If you’ve been watching the news headlines lately, you’ll have no doubt heard the controversy over Michael Mosley’s new programme on channel 4.

The aim of this programme is for people to lose 1 stone (~6.5kg) in 21 days.

This experiment is led by scientific journalist Michael Mosely, who places 5 volunteers on a very low-calorie diet and then closely monitors any changes to their fat and muscle throughout the 21 days.

This programme has aired just as the government have focussed attention on improving obesity prevention, due to the link to poorer outcomes from coronavirus (COVID-19).

We do agree that there are some valid points made in this programme, including:

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If you have weight to lose, losing weight is beneficial for your health
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It’s important to look at more than just BMI (including waist measurement and fat:muscle ratios)
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Being overweight or obese has been shown to increase your chances of complications if you catch coronavirus (COVID-19)
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Following a very low-calorie diet will result in weight loss.

However, we also have a few concerns with the programme and how this ‘experiment’ has been set up, including:

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Promoting shame around being overweight or obese isn’t an effective weight-loss strategy
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Participants psychological wellbeing and supporting mental health wasn’t considered, which plays a big role in sustainable lifestyle changes
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Following a balanced, very low-calorie diet isn’t realistic or sustainable for the majority of people
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An attention-grabbing title which targets people’s insecurities and then shows an unrealistic approach (for most people, unsupervised) is questionable.

In this article, we’re going to go into more detail about the valid points and issues that we see with this programme. It’s worth noting that this review focuses on episode 1 of the series.

A very low-calorie diet

It’s not that participants won’t lose weight on a very low-calorie diet. In fact, we’re sure that they will. Cutting our energy intake dramatically will result in a negative energy balance, which means we’re burning up more energy than we’re putting in. This will almost certainly lead to weight loss.

A large, ongoing study called the DIRECT trial demonstrated that significantly more individuals with type 2 diabetes achieved remission when placed on a very low-calorie diet, compared with those given standard NHS care for type 2 diabetes.

This study was the first of its kind to demonstrate that losing a significant amount of body fat can help many people achieve type 2 diabetes remission. However, that doesn’t mean that it’s a realistic, long-term diet for most people.

For context, Michael Mosely’s diet programme provides 800 calories a day, and the recommended daily number of calories is 2,000 and 2,500 for females and males respectively. That’s less than half of what many of us should eat in a day.

So what’s the issue?

Everyone’s unique

We’re all unique. An approach that might work for one of us won’t necessarily suit someone else. For most individuals who’re looking to lose weight and keep it off in the long term, a lower-carbohydrate diet, where you reduce the number of carbs you’re eating but don’t eliminate them from your diet, seems to be the most effective for weight loss.

For some people, excluding carbs entirely from their diet might be too drastic an approach or unrealistic for their specific lifestyle or dietary needs. In those circumstances, it would be counterproductive, as it’d most likely lead to them giving up. The best ‘diet’ is one that we can incorporate into our lives and stick to in the long term.

A much more effective way to approach weight loss in real-life settings is to follow a plan created by registered nutritionists and dietitians who take your preferences and lifestyle into account.

Is keto best?

The diet at the beginning of this series is essentially a very low-calorie, ketogenic (keto) diet. It’s important to note that there’s a difference between a ‘low/lower carbohydrate’ diet and a ‘ketogenic’ diet.

The ketogenic diet (keto) is high in fat and eliminates carbs almost entirely. By doing this, the body is deprived of its primary fuel source, glucose. The body then creates new metabolic pathways and starts to function using fatty acids from fat stores and dietary fat intake. Over time, ketones which are produced from the breakdown of fat will start to be used by the brain for energy instead of glucose. This process is called ketosis.

While this may sound ideal, the keto diet can be challenging to follow effectively in the long term. It’s much more restrictive and one ‘slip up’ will take you out of ketosis temporarily.

Volunteers in the programme report feeling dizzy, nauseous, faint, and generally unwell. This is common when transitioning into ketosis and is known informally as ‘keto flu’. These participants are medically supervised and regularly monitored, but this might not be suitable for those of us attempting this diet alone within the context of a busy schedule.

In this programme, participants will follow a keto, very-low calorie diet for a period of time and then slowly introduce carbs back into their diet. Although it’s likely this programme was created to make headlines and to prove that quick weight loss is possible, we don’t believe that it stresses enough that this approach shouldn’t be adopted by everyone without supervision.

For most people, a lower-carb diet, rather than keto, is the most sustainable to follow in the long run and won’t cause the same short-term side effects.

Fuelling the problems with ‘diet’ culture

There are many different factors that should be considered when losing weight – it’s not as simple as ‘eat less, move more’.

Many of us feel demotivated to make healthy changes because of the pressures and judgement that come from society. The recent government obesity strategy has been questioned because of this.

A lot of the language used in the first episode of this programme harbours a shame culture around being overweight or gaining weight. Within 3 minutes, Dr Mosely is discussing the rise of the ‘lockdown belly’ and how many of us have ‘piled on’ the ‘corona kilos’.

For many people, the pandemic has been an incredibly challenging, unsettling period. Between worrying about loved ones, job uncertainty, and disruption to our daily lives, many people have struggled to keep up a healthy routine.

Encouraging people to harbour guilt for this is, in our opinion, unfair and counter-productive. One volunteer openly discusses how she longs to ‘be normal’ and not think about her weight every time she eats. This mindset can be a huge obstacle for many individuals looking to change their lifestyle, and support should be offered to adjust this mindset, rather than encouraging it, so that any healthy changes can be sustained in the long run.

Considering two-thirds of people regain all the weight they lost and then some following a strict diet, it’s incredibly important to think in the long term rather than in the short term.

Psychological health is key

Stress is one of the most important factors to manage if you’re trying to lose weight, yet very few of us consider our stress levels when making healthy changes. Evidence suggests that stress can lead to weight gain, both indirectly and directly.

Near the start of the first episode, participants discuss feeling lonely, dealing with job loss, and battling with unhealthy relationships with food. All of these factors have an impact on mental health and ignoring this piece of the puzzle is likely to result in participants giving up or regaining the weight they lose (and then some) in this 21-day period.

On top of this, scaremongering people into finding out their ‘metabolic age’ only contributes to stress and anxiety. Everyone responds differently, and although some individuals might benefit from a stern push, it might simply induce further anxiety for others. We’d hope that there’s a focus on mindset and some psychological support behind the cameras, but on camera, there’s no mention of either.

An alternative approach

At Second Nature we know that shaming people about their weight isn’t an effective weight loss strategy. Instead, education around nutrition, exercise, sleep, and stress, alongside advice from a registered dietitian or nutritionist health coach, is a much more effective and long-term approach.

The Second Nature programme provides:

  1. 1-1 digital support from a registered dietitian or nutritionist, keeping you motivated and accountable
  2. A digital peer group to help you work through challenges and share your achievements
  3. Habit-change techniques to improve your nutrition, sleep, stress, activity levels, and more
  4. Daily educational articles
  5. Simple recipes with step-by-step videos that won’t leave you feeling hungry
  6. No calorie counting. No fad diets. No hunger.
  7. Tracking technology to track your weight, steps, and sleep.

A barrier that many of us face is the time and cost commitments that in-person programmes demand. The Second Nature programme is done entirely digitally, so you get all these benefits from the comfort of your home at a time that suits you, without paying for travel or taking time off work.

Get your free 5 day plan today

Write a response

amanda marsden
15 November, 2020

Please could I have the 5 day free recipes


Shirley Geraghty
8 September, 2020

The Direct trial doesn’t cut out carbohydrates, the food on the very low calorie diet (actually made by Cambridge Weight Plan) contains all food groups including carbs.


Trudie Zabrana
25 August, 2020

Funny that Michael Mosely and his wife have more important qualifications as Doctors rather than journalists – as did the Scarsdale diet developer. Against your red crosses I would like to reply that while shame is not beneficial neither is it of any help to tell an overweight person that it is OK – On a purely health basis it is not OK – it is killing them. An attention grabbing title may just motivate people to try harder and while I would agree that a very low calorie diet is not for everyone, please take into consideration that there are many people who can eat 2000 calories plus without any real nutrition. Better to get 800 calories of fish meat, veg and fruits than 2000 calories which includes lots of treats to make you “feel better”. Having battled with weight for most of my life it is my experience that the only way to get or keep slim is to eat less food and ensure there is enough protein, vitamins and minerals to stay as healthy as possible. One of my best friends and greatest supporters has always maintained that when given the list of excuses for being overweight that it is strange that no one ever came out of a concentration camp overweight. Sad but true


Tamara Willner
26 August, 2020

Hi Trudie, thank you for your comment! We totally agree that telling people who have weight to lose that it’s healthy isn’t the right route. However, we’d argue that there’s a difference between shaming individuals who’re looking to lose weight and actually supporting and educating them (including supporting their mental health). Evidence suggests that a lower-carb approach results in weight loss which is sustained over a long period of time. You can find out more details about a lower-carb diet in our guide here. Many people on our programme find that they aren’t hungry, which helps them stick to their healthy eating plan. On a calorie-restricted diet, people are often left unsatisfied, which can lead to them giving up after a period.


Jo Mc
15 August, 2020

Fantastic article. I do find that stereotypical ‘lockdown belly’s as was described by the program is quite unsupported of those who have actually lost weight since lockdown.