Discover the best way to lose weight for life…

The science behind Slimming World

Founded in 1969, Slimming World is the UK’s most advanced and effective weight management organisation. Every year, we help millions of people to lead a healthier lifestyle

Slimming World’s philosophy is based on a deep understanding of how people with a weight problem feel, coupled with a passionate desire to help them achieve their goals. Over 50 years, our programme has been developed and refined in line with the latest thinking on nutrition, exercise and the psychology of behaviour change. Slimming World groups are run by a network of Consultants, all of whom have been successful group members, and who work in their local community. Consultants receive specific training in dietary aspects of weight management, the role of physical activity and, importantly, effective facilitation of behaviour change.

Our multi–component approach

Slimming World integrates three key principles to help people adopt a healthier lifestyle:

A satisfying eating plan

Food Optimising – which promotes healthy eating patterns for life.

An activity programme

Our unique physical activity programme is tailorable and suitable for all fitness and mobility levels.

A warm, empowering group environment

IMAGE Therapy – which supports members and facilitates behaviour change around eating and activity habits.

Food Optimising – a healthy, satisfying eating plan

Food Optimising is a flexible eating plan designed to create healthy eating patterns that can be maintained long term. It’s based on nutrition science that shows that foods higher in protein and carbohydrate are more satiating than foods high in fat. Encouraging a higher intake of more satiating foods helps to limit energy intake and results in weight loss. Food Optimising combines the principles of energy density (the calories per gram in a food) and satiety (how filling a food is). A typical Food Optimising daily menu includes at least five portions of fruits and vegetables alongside a healthy amount of lean protein-rich foods and carbohydrates, measured portions of fibre- and calcium-rich foods, and a reduction in overall fat, saturated fat and free sugars (the sugars that are not naturally found in fruit and vegetables).

The Food Optimising plan focuses on three components…

Free Foods

Free Foods are those foods that satisfy the appetite while reducing overall energy intake. They include lean meats, poultry, fish, eggs, vegetables, fruit, grains, potatoes and pasta. We encourage members to eat them abundantly. They are what makes Food Optimising so easy to establish and sustain, compared to weight loss plans that leave people feeling hungry and deprived.

Healthy Extras

Healthy Extras are measured amounts of foods eaten each day to provide a good overall balance of nutrients in addition to those obtained from Free Food. There is particular emphasis on calcium- and fibre-rich foods, including cheese, cereals and wholemeal bread.


Syns are the way members can guiltlessly enjoy the foods that many weight loss plans ban outright. Counting Syns helps members naturally limit their intake of more energy-dense foods such as fats, alcohol and sugar. These foods have a poor ability to satisfy hunger and, when consumed in large amounts, make weight loss difficult.

Body Magic – a rewarding step-by-step activity programme

Our Body Magic activity programme helps members gradually increase physical activity levels and improve overall health and wellbeing. It’s informed by a deep understanding of the barriers overweight people often face in becoming more active. Developed in collaboration with Professor Ken Fox, a renowned exercise and public health expert, author, and government advisor, Body Magic uses well–established psychological and scientific principles of behaviour change. It helps people find their own personal, enjoyable, and sustainable ways of increasing activity and making it a part of their daily routine.

Our physical activity programme,Body Magic, will help you to:

  • break down any personal barriers, misconceptions or worries that may be stopping you from getting going
  • feel the amazing benefits that being physically active brings, which include having more energy and improved health and wellbeing. Plus, when you reach your dream weight, it can help you stay slim for life!
  • build – or build up – your active habits in a way that’s enjoyable and sustainable with the overall aim of making physical activity an intrinsic part of your life
  • find new physical activities you love – which give you the feel-good factor, suit you and fit into your lifestyle
  • continually find ways to take things up a gear and get even more benefits from different active habits, such as building bone and muscle strength and improving flexibility and balance
  • celebrate every milestone along the way with tonnes of praise and encouragement, from day one right up to your Platinum Body Magic award, where you’re meeting the government’s recommended guidelines and physical activity is just a way of life!

A warm, empowering group environment

Slimming World’s unique group support system is a rich weave of individual support in a powerfully motivating group setting. It avoids any criticism, control or judgement and uses elements of behaviour–change techniques including Transactional Analysis, Motivational Interviewing and the influence of ego states on behaviour to help people overcome their personal barriers to change and to avoid relapse. At Slimming World we call this positive support structure IMAGE (Individual Motivation And Group Experience) Therapy. Based on a deep understanding of the psychology of overweight people, our support system is designed to increase the confidence and self–esteem of our members, while equipping them with tools to develop lasting self–determined behaviour change. Our support is based on the belief that the burden carried by overweight people is two–fold. There’s the burden of excess weight itself, but there’s also a far heavier burden to be lifted – that of shame, self–criticism and poor self–esteem. For many overweight people, successful long–term weight loss can only be achieved by tackling these deeper emotional issues and this support is only effective when it’s delivered with genuine warmth, compassion, empathy, respect and understanding. We have a sincere belief in the power of group support – the power for individuals to support and be supported, to inspire and be inspired, and to take members through the phases of commitment to change. IMAGE Therapy guides members through psychological and behavioural commitment, reinforcing these consistently until behaviour becomes intrinsic, ie it has become important to our members and they’re no longer dependent on the group to receive reward or praise.

Our online service

The weekly support provided to members in group is strengthened through our digital service, which members can access whenever they like. For people who aren’t able to access a group, or prefer not to, we have an enhanced digital service, Slimming World Online, which enables members to follow our Food Optimising plan, our step–by–step activity programme and receive empowering support via an online community. The digital service includes an app for iOS and Android users, providing a rich library of supportive content and personalised tools that helps members find support based on their particular situation.

Want to

know more?

To find out even more about Slimming World’s approach and evidence base, visit our

Health professionals website