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New research from the University of Lincoln shows that members who are supported to lose weight in a Slimming World group not only get great results on the scales – they can also increase their mental toughness. 

The six-month study, which is the first of its kind in the UK, found that: 

  • On average, Slimming World members lost over 2st more than those in a comparison group.   
  • Measures of mental toughness rose 10% in Slimming World group members, whereas there was no statistically signifcant change in the comparison group.   

The findings of the study, led by Dr Elizabeth Stamp, a lecturer at Loughborough University, come at a time when the UK population faces a spiralling obesity crisis and increased mental health challenges. 

Government figures suggest more than 40% of adults in England gained weight during the pandemic*, with the average gain being half a stone, while more than half of adults (60%) and more than two thirds of young people (68%) said their mental health suffered during lockdown**.  

Joining a slimming group with expertise in helping people to change lifelong habits is well established as a successful way to tackle weight gain. But it’s only now we’ve discovered what an impact a supportive group environment can have on mental toughness. 

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Kirsty’s weight loss story 

Slimming World member Kirsty Muir before and after photo

Kirsty Muir lost 7st with Slimming World – developing new healthy habits, improving her health and gaining genuine confidence along the way. Kirsty says:

“When I joined Slimming World in 2019, I weighed 18st 5lbs and it was causing issues – not just with how I felt physically, but how I felt emotionally, too. When you’re overweight, people assume you’re the biggest personality in the room. And while I might have seemed confident on the outside, I was actually very shy and self-conscious. I was also eating in secret and, after doing the food shopping, I’d sit in the supermarket car park eating treats – anything from a couple of doughnuts to cakes, sweets or crisps. Then I’d have another treat when I got home.

Slimming World member Kirsty Muir face to face transformation

Slimming World has helped me to break this habit, because I never feel hungry. I also know that I can have a treat if I want one – I don’t have to cut anything out and I don’t feel the need to snack in secret any more. I’ve learnt how to cook from scratch, whereas before everything I ate was shop-bought junk food.

Kirsty’s before and after menu


Breakfast: On a weekday, I would grab a bacon, sausage or black pudding roll from the local shop, followed by a latte with two sugars. At the weekend, I’d have a fried full English or a bowl of sugary cereal.

Lunch: Fish and chips or a sandwich from the office canteen, with a bar of chocolate, a packet of crisps and a sugary drink.

Dinner: A lot of processed foods, a shop-bought pizza or curry and garlic bread.

Snacks: Cakes, crisps, bars of chocolate, sweets.


Breakfast: Weetabix with blueberries and honey or overnight oats.

Lunch: Leftovers from the Slimming World dinner the night before, or a baked potato and beans. Juice with no added sugar and coffee with sweetener.

Dinner: Slimming World cottage pie or teriyaki salmon with lots of vegetables or salad. If I’m pushed for time, I’ll have something from the Slimming World food range at Iceland, with some extra veg on the side.

Snacks: Slimming World Hi-Fi bar, fruit, home-made houmous with carrots to dip, low-fat crisps.

My life has changed completely since joining Slimming World. I walk a lot more and I love taking my two dogs out three times a day. I’ve even joined a gym, which is something I never thought I’d be able to do.

I’ve gone from being a size 20 to a size 10 and my confidence has grown so much. And I wouldn’t be the person I am now without the support I get from going to group each week.”

MORE FOR MEMBERS: Read more about making changes that stick – so that you can stay slim for life!

Understanding the link between Slimming World support and mental toughness

Dr Jacquie Lavin, Slimming World’s head of research and scientific affairs, says: “Kirsty’s story shows the depth of understanding about the psychology of weight loss that we have at Slimming World. It’s been at the heart of our method for more than five decades. In our groups we share techniques to empower and enable members to make their own behaviour changes through a variety of methods, including setting goals and developing skills to overcome barriers by facing and seeking out challenges and taking back control, which are all linked to the principles of improving mental toughness. By encouraging our members to try new foods, transform old, unhealthy habits and change their perception of food and activity, we create an environment where our members can challenge themselves on their own timescales.”

Professor Peter Clough*** developed the 4Cs model of mental toughness: challenge, commitment, confidence and control. The study found that Slimming World members had increased scores in all of the 4Cs during the six-month study.

Slimming World mental toughness infographic

Dr Elizabeth Stamp, who studied the role of mental toughness on health-related lifestyle behaviour change at the University of Lincoln, says: “Looking at the 4Cs model, it’s understandable that Slimming World members showed an increase in mental-toughness scores. The multi-level support which the group provides is specifically designed to help members increase their commitment to their weight loss and make the changes needed to ensure they achieve them. It supports them to feel in control of their choices and behaviours and feel more confident in their ability to make the changes, even in situations where their commitment and motivation would otherwise be challenged (for example, eating out, travelling, staying away from home, socialising, etc). Helping members think about the challenges, make plans for when things may get in the way and develop strategies for these times are all ways in which the group supports members to stick to their plans and successfully lose weight each week.”

*Public Health England: Better Health Adult Obesity Study, 2021

**The Mental Health Emergency study by Mind, June 2020

***Professor Peter Clough is technical director of AQR International and the writer and co-writer of almost 50 articles and books on mental toughness, including 2002’s Developing Mental Toughness

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