What is it?

The Slimming World diet is run by a Derbyshire based weight loss company set up in 1969 by founder Margaret Miles-Bramwell.

Slimming World claims that the diet works through a multitude of proven, evidence-based methods.

The method based around food is known as ‘Food Optimising’, the physical activity is known as ‘Body Magic’, and it comes with a group support system called ‘IMAGE Therapy’.

‘Food Optimising’ attempts to be a flexible eating plan that is easy-to-follow, rather than the typical restrictive diet that aims to burn the most amount of fat in the shortest possible time.

Members choose from a list of given ‘free foods’ that are selected for their health benefits, as well as being high-satiety foods that will certainly reduce hunger and reduce caloric intake.

Slimming World’s ‘free foods’ are focused heavily on a wide range of fruits, vegetables, pasta, rice, potatoes, eggs, lean meat and fish.

‘Free foods’ can be eaten in unlimited quantities throughout the day.

As well as free foods, members are given the option to include ‘Healthy Extras’, but these are on a restricted basis. These are foods that are mostly still relatively high in fibre, but may be more calorically dense that the ‘free foods’, and include wholegrain cereals, wholemeal breads and crackers, nuts and healthy oils.

No foods are banned, but there is a controlled intake of more energy dense foods, including sweets and alcoholic beverages, which are called ‘syns’, that users will recognise as treats.

Similar to Weight Watchers, Slimming World is more of a marketable support system for first-time dieters looking for an encouraging, positive environment to help with their journey. As well as providing general tips on healthy eating and how you can enjoy different forms of exercise, Slimming World has 13,000 weekly support groups, 4,000 Slimming World trained consultants and 800,000 members attending each week.

Unfortunately, like all similar support systems, it comes with a price. It costs £10 to join a Slimming World group, followed by payments of £4.95 each week with discounts for various groups of people. Different fees apply to those who want to follow the diet online without attending group sessions.

The program marketers claim that, on average, members lose around 8% of their weight in 6 months and around 13% by 12 months. Although evidence would be needed for these claims to be confirmed, it does seem that Slimming World gets a lot of positive feedback and reviews from those that have decided to purchase a subscription.

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The Benefits

  • Positive, empowering environment – For many people, telling them what to eat, when to eat and why, is only the first step and will not necessarily equate to long-term success and happiness.

Depending on an individual’s personality, taking responsibility and control of a lifestyle change can be overwhelming when done alone and without moral support.

Social support can trigger behaviour change by providing information about diet or exercise, by providing reassurance, or by increasing compliance to treatment. Cross-sectional studies have also related social support to health, and social support has also shown to be important in achieving and maintaining health behaviour change [1][2].

Slimming Worlds support groups and trained consultants are a great way to encourage individuals to make better choices and focus on the benefits to their new decisions as opposed to thinking negatively about the relative restrictions they are imposing on themselves.

After all, dieting for everyone is not black and white and is more of a multifactorial system revolving around keeping a positive psychological state.

  • Focus on high-satiety foods – Slimming World focuses on reducing caloric intake through increasing the consumption of foods that will cause hunger levels to be low compared to previous dietary habits.

Fruits, vegetables, and potatoes being the staples of the diet will undoubtedly do their job at minimizing snacking in between meals and not leave the user craving their next treat.

Interestingly, the Slimming World diet is nearly identical to a diet recommended by the American Heart Association, which has shown, on average, to lose ~6 pounds in 12 months based on 240 participants [3].

Epidemiological data also suggests dietary fibre intake is inversely correlated with body weight and body fat, and there is speculation that fibre works outside of just promoting satiation and weight management by altering the secretion of certain beneficial gut hormones [4].

The American Dietetics Association also states dietary fibre is the leading influencer of total caloric intake, and should be the focal point of any weight loss phase [5].

Not to mention that aside from body composition benefits, dietary fibre is essential for good health, improving cholesterol, triglyceride and insulin levels whilst reducing chances of many diseases [6].

  • Flexibility – Unlike most diets sweeping the internet today (i.e fad diets), Slimming World incorporates the ideology that flexibility is key to a successful diet.

Although you can choose to stick to the fundamental foods of the diet at all times, the diet gives you the option to delve into the principle of moderation, occasionally treating yourself to your favourite foods.

This concept seems to lead to better diet adherence in the long-term as opposed to being overly strict with every aspect of the diet, and will likely work wonders for your wellbeing and satisfaction. Although the diet does name certain foods as ‘syns’, this is more a play on words and they do encourage flexibility as long as the individual takes responsibility for not exceeding the line between moderation and stupidity.

The Cons

  • No dietary tracking for more advanced dieters – Although the principles of the Slimming World diet are sound, they do not meet the requirements for more advanced individuals, specifically athletes/bodybuilders/powerlifters.

Sticking to consistent healthy eating behaviours will likely put everyone at a healthy bodyfat percentage if done for long enough (for men: 12-18%, for women: 18-24%), and this diet is suitable for anyone with this aim.

For those looking to excel in body composition or athletics, it may be necessary to go beyond these healthy markers of body fat levels, and this comes hand-in-hand with a more restrictive, controlled dietary approach. Slimming World does not calculate macronutrient or micronutrient targets, does not incorporate meal timing, and does not make adjustments as progress begins to stall, all of which is crucial in the world of sports nutrition.

  • It is a paid service – Diets should never be purchased unless you are getting a unique, personalised plan that caters to your requirements.

There is simply too much good, free, accessible information online to waste your money on what could be found from a Google search.

Money would be better spent hiring a personal nutritionist or dietician to assess your needs and build a plan around your lifestyle that can bring success as well as being easy to implement.

Generic diet plans are simply that, generic. As mentioned earlier, the information given by Slimming World can be learnt by reading the free information released by the world’s leading health organisations (all of which is less than 2 hours reading time!).

That being said, if you wish to pay Slimming World for their social support and member benefits, I encourage you to do so as it may be the tool you need to push yourself further than ever before. It is nearly £300 annually for full access to Slimming World, and it is down to the individual whether the cost is worth the reward.

Who should run the diet?

Slimming World is a great option for individuals looking to join a positive, goal-orientated group where you can meet new friends and get advice from knowledgeable health professionals.

Slimming World is more than a diet, and will help you with other aspects of the journey such as offering group sessions, consultations and giving weekly healthy meal ideas. It is a great business that is set up to help the average person looking to lose excess weight and feel better about themselves, whilst opting away from the ever popular restrictive, stressful fad diets.

Athletes, or those looking to achieve ‘extreme’ levels of health, performance and/or body composition should look for a more nutrient-orientated programme that focuses on the details of nutrition.

Slimming World revolves around basic principles of healthy eating and will likely not be optimal when aiming to maximise progress in sport or performance. In addition, those unwilling to pay a subscription for a diet or support network would be better off choosing another diet to follow as Slimming World requires you to splash the cash.



  1. Amick TL, Ockene JK. (1994). The role of social support in the modification of risk factors for cardiovascular disease. In Social Support and Cardiovascular Disease. New York: Plenum Press.
  2. House JS, Landis KR, Umberson D. (1988). Social relationships and health.Science
  3. Harvard Medical School. (2015). Making one change — getting more fiber — can help with weight loss. Available from: http://www.health.harvard.edu/blog/making-one-change-getting-fiber-can-help-weight-loss-201502177721
  4. Slavin JL. (2015). Dietary fiber and body weight. Nutrition
  5. Champagne CM, Broyles ST, Moran LD, Cash CK. (2011). Dietary intakes associated with successful weight loss and maintenance during the Weight Loss Maintenance Trial. J Am Diet Assoc.
  6. Curtin University. (2012). Weight loss and fibre relationship to be studied. Available from: http://news.curtin.edu.au/media-releases/weight-loss-and-fibre-relationship-to-be-studied/