The Slimming World diet is a flexible eating plan that originated in Great Britain.

It promotes balanced eating with occasional indulgences and doesn’t involve calorie counting or food restrictions, with the intent of encouraging lifelong healthy behaviors.

In recent years, the Slimming World diet has become incredibly popular in the United States.

Several studies suggest that it may be effective for losing weight and making healthy behavior changes, but it also has some downsides (1, 2, 3).

This article reviews the Slimming World diet and whether it works for weight loss.

  • Overall score: 4.21
  • Weight loss: 4.5
  • Healthy eating: 5
  • Sustainability: 4.25
  • Whole body health: 3.5
  • Nutrition quality: 4
  • Evidence based: 4

BOTTOM LINE: The Slimming World diet discourages calorie counting and focuses on healthy foods, occasional indulgences, group support, and increased physical activity. It may aid weight loss and encourages healthy habits.

Slimming World was founded 50 years ago in Great Britain by Margaret Miles-Bramwell.

Today, it continues to implement its original model of nonrestrictive healthy eating and a supportive group environment (4).

The goal of the program is to help you lose weight and develop healthy behaviors without feeling shame or anxiety around food choices or obsessing over calorie restriction (4).

Specifically, Slimming World promotes a style of eating called Food Optimizing that involves filling up on lean proteins, starches, fruits, and vegetables; adding dairy and whole grain products that are high in calcium and fiber; and occasionally eating treats.

Proponents claim that this way of eating and indulging in treats when you crave them makes you more likely to accomplish your healthy eating and weight loss goals (4).

The Slimming World program also provides weekly support groups online or in person in certain areas, as well as ideas for developing exercise routines (4).

Pros at a glance

  • may lead to sustainable weight loss
  • discourages calorie counting
  • encourages eating healthy foods and occasional indulgences
  • convenient and accessible for most people

Cons at a glance

  • can be expensive for some people
  • does not teach portion control
  • requires adequate cooking skills
  • may be difficult to attend in-person meetings
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Anyone can get started with the Slimming World diet by signing up for the community online at the program’s U.S. or U.K. website.

Members of the Slimming World community are instructed on Food Optimizing, which involves the following three steps (4, 5):

  1. Fill up on “Free Foods.” These are healthy and satisfying foods, such as lean meats, eggs, fish, whole wheat pasta, potatoes, veggies, and fruits.
  2. Add “Healthy Extras.” These add-ins are rich in calcium, fiber, and other important nutrients. This category includes dairy foods, nuts, seeds, and whole grains.
  3. Enjoy a few “Syns.” With a name that’s short for “synergy,” Syns are occasional treats, such as alcohol and sweets that are high in calories.

To help members get comfortable with Food Optimizing, Slimming World provides recipes and lists of foods in these categories via their website and smartphone app. There are no rules involving calorie counting or food restriction.

Members also have access to weekly group meetings that are led online or in person by a trained Slimming World consultant. These meetings are intended to provide further guidance and support.

Specifically, members have the opportunity to discuss their experiences and self-identified behavior patterns that may hinder successful weight loss. With the help of the group, members can brainstorm new ways of overcoming their personal barriers (1).

When members feel that they’re ready to develop an exercise routine, Slimming World provides support, activity journals, and ideas for gradually increasing your physical activity.

Slimming World online membership packages (Bronze, Silver, or Gold) cost $63–84 for 3 months. After you sign up for an initial subscription, it costs $26 per month to continue (6).

The Bronze package includes a 3-month membership and three introductory guides.

The Silver package includes all this and two Slimming World recipe books.

Finally, the Gold package includes everything in the Bronze and Silver packages as well as a 1-year subscription to the Slimming World magazine (6).

All packages include access to the Slimming World app, which features recipes, meal tracking and planning tools, various workouts, and community message boards. Users can also attend in-person group sessions, which you can find through the website.

Members of Slimming World can discontinue their membership at any time and do not need to purchase any specific supplements or additional materials during the program.

Several studies indicate that Slimming World may be effective for weight loss.

This may be because Slimming World’s flexible style of eating helps people stay on track without feeling overly restricted, thus making them more likely to achieve their weight loss goals (7, 8, 9).

One study in 1.3 million adults who attended weekly Slimming World meetings in the United Kingdom and Ireland found that those who went to at least 75% of the sessions lost an average of 7.5% of their starting weight over 3 months (1).

In an older study from 2012 that included close to 5,000 adults. researchers observed that participants who went to 20 of 24 Slimming World sessions over 6 months lost 19.6 pounds (lbs.) (8.9 kg) on average (10).

Other studies offer similar results, suggesting that attending most of the weekly support meetings is associated with the greatest weight loss on this diet (2, 3, 7, 11).

However, keep in mind that several of these studies were funded by Slimming World, which may have influenced results (1, 3, 7, 10, 11).

Nevertheless, the consistent results suggest that this diet may be an effective method for losing weight in a healthy way. Slimming World also encourages regular physical activity, which further supports weight loss.

Still, as with any other diet, losing weight with Slimming World may depend on each individual’s adherence to the program, involvement in group meetings, and membership duration.

There are other potential benefits to the Slimming World diet.

May improve general health habits

In addition to helping you reach weight loss goals, the Slimming World diet may help you develop lasting healthy habits and improve your overall health.

One study in 325 females analyzed dietary patterns before and after joining Slimming World. On average, daily fiber intake significantly increased, from 24 grams to 32 grams, while consumption of calories from simple sugars significantly decreased, from 12.6% to 8.7% (12).

This is in line with most dietary guidelines, such as the Dietary Guidelines for Americans, which recommend consuming more fiber and fewer foods high in simple sugars for weight management (13).

Another older study, from 2009, in close to 3,000 adults found that those on the Slimming World diet reported a significant change in preference for healthier foods and an increase in physical activity after starting the program (14).

What’s more, more than 80% of participants noted an improvement in their overall health (14).

These results suggest that Slimming World may help people implement changes that not only promote weight loss but also improve several aspects of health.

May lower risk of chronic conditions

Because Slimming World helps people lose weight, it may help reduce the effects of and lower the risk of obesity-related chronic conditions such as type 2 diabetes, high blood pressure, and heart disease.

One 2019 study funded by Slimming World included 69 people who had both obesity and diabetes.

Those who participated in Slimming World groups for 12–24 weeks had an average weight loss of 5.5% and an average reduction in BMI from 37.7 to 35.9. Additionally, 81.2% of participants experienced reductions in hemoglobin A1c (HbA1c) levels (3).

However, there were no significant changes to participants’ blood pressure, cholesterol levels, or triglyceride levels. Therefore, it’s unknown how the diet improves heart health and whether a longer duration is necessary to produce positive results (3).

More research is needed on the effects of Slimming World on these conditions.

Convenient and accessible

A major benefit of Slimming World is that it offers both in-person and online support, making it convenient and accessible for its users.

The app is easy to use and provides numerous resources to support healthy lifestyle choices, such as healthy recipes, meal planning tools, and workout programs.

Further, additional in-person support is available for those who prefer more personal interactions and guidance.

Though the Slimming World diet may help people lose weight, it has some downsides.

May be hard for those with busy schedules

Losing weight with Slimming World depends on each person’s commitment to the program.

While participants have the option of attending group sessions online instead of in person, it may still be difficult for some to fit the meetings into their busy schedules. If a person would be more motivated by in-person coaching, this may hinder their success.

Presents a learning curve for those who don’t cook often

Preparing healthy Slimming World recipes may be challenging for people with limited cooking skills and time.

Though the app provides many delicious and nutritious recipes, a person with limited food skills may have difficulty making some dishes. This is especially true for some advanced cooking techniques, such as cooking various meats or putting an entire meal together from scratch.

As such, there may be an initial time commitment to overcome this learning curve, which may be hard for people with busy schedules.

However, while it may be inconvenient at first, learning new food skills can actually help a person develop confidence in preparing healthier dishes.

May make portion control tricky

Finally, because Slimming World discourages calorie counting and doesn’t specify appropriate portion sizes for the Free Foods, some people may overeat these foods. Fortunately, many of the Free Foods are higher in protein, starches, and fiber, which tend to be filling.

The app does provide helpful recipes with portion sizes and guidance on portion sizes for the Healthy Extras and Syns.

The Slimming World program divides foods into three categories: Free Foods, Healthy Extras, and Syns.

Free Foods are filling but low in calories. On the Slimming World diet, these foods should make up the majority of your meals and snacks. This category includes but is not limited to (15):

  • Lean proteins: eggs, beef, chicken, pork, turkey, salmon, white fish (cod, tilapia, halibut, and most others), shellfish (crab, shrimp, lobster, and others)
  • Starches: potatoes, rice, quinoa, farro, couscous, pita bread, beans, whole wheat and white pasta
  • All fruits and vegetables: broccoli, spinach, cauliflower, bell peppers, berries, apples, bananas, oranges

To meet your daily fiber, calcium, and healthy fat recommendations, the Slimming World diet also includes Healthy Extras. Recommended portions vary depending on the food. The materials provided when you sign up for the program include further explanation of this.

The program generally suggests adding two Healthy Extra “A choices” (foods high in calcium) and one “B choice” (high fiber grains) each day. High fat nuts and seeds are encouraged in moderation.

Some examples of these extras are (15):

  • Dairy products: milk, cottage cheese, other cheeses, low fat or fat-free Greek and plain yogurt
  • High fiber whole grains and cereal products: whole grain bread, oats
  • Nuts and seeds: almonds, walnuts, pistachios, flaxseed, chia seeds

The program offers several recipes and meal ideas that focus primarily on lean proteins, fruits, vegetables, and “free” starches, with smaller portions of Healthy Extras.

All foods are allowed on the Slimming World diet, but sweets, highly processed foods, and alcohol are meant to be limited to some extent.

Additionally, all foods that aren’t Free Foods have a Syn value, which ranges depending on the food. Details are available in the app or in the materials provided when you sign up.

Members are encouraged to enjoy Syns from time to time to satisfy cravings and help them feel less tempted to go off track. The portions will depend on your individual needs and goals. Generally, the program suggests consuming no more than 15 Syns per day.

Some examples of Syns are (15):

  • Sweets: doughnuts, cookies, cakes, candies, biscuits
  • Alcohol: beer, wine, vodka, gin, tequila, sugary mixed drinks
  • Sugary drinks: sodas, fruit juices, energy drinks
  • High calorie condiments: mayonnaise, ranch dressing, Caesar dressing

Since the Slimming World diet doesn’t restrict any foods, it’s very easy to follow.

Here is a sample 3-day menu for the Slimming World diet.

Day 1

  • Breakfast: steel cut oatmeal with fruit and walnuts
  • Lunch: Southwest chopped salad with black beans
  • Dinner: sesame chicken with rice and broccoli, plus a small brownie
  • Snacks: string cheese; celery and hummus; tortilla chips and salsa

Day 2

  • Breakfast: eggs, potato hash, blueberries
  • Lunch: turkey-and-vegetable quinoa salad
  • Dinner: spaghetti and meatballs with vegetable sauce and a glass of wine
  • Snacks: fruit salad, trail mix, carrots, avocado

Day 3

  • Breakfast: whole grain French toast with strawberries
  • Lunch: minestrone soup with a side salad
  • Dinner: pork chops, mashed potatoes, and green beans
  • Snacks: hard-boiled eggs; dark chocolate squares; apples and peanut butter

You can use the Slimming World app to design your own meal plan from the many healthy recipes provided on the website and in the app.

Can you eat bread on Slimming World diet?

Yes, you can eat bread on the Slimming World diet. It’s considered a Healthy Extra “B choice” — a category that includes high fiber foods. You can add one serving (two slices) of whole grain bread to your diet once per day (16).

What foods can you eat on Slimming World diet?

The Slimming World diet allows you to eat an unlimited amount of Free Foods, which are often low in calories and high in nutrients. These include lean proteins, starches, fruits, and vegetables.

You’re also encouraged to include foods rich in calcium and fiber to meet your nutrient needs.

There are no recommended portion sizes for Free Foods, and no calorie counting is involved.

How much weight can you lose in a week on Slimming World?

Since the Slimming World diet does not give specific calorie goals, different people will lose weight at different rates.

Generally, losing 1–2 pounds (0.45–0.9 kg) per week is considered healthy and sustainable for most people as long as they do not feel deprived and consume a variety of nutritious foods (17).

The Slimming World diet is a flexible eating plan that discourages calorie counting and focuses on healthy foods, occasional indulgences, support through online or in-person meetings, and increased physical activity.

Research shows that it may aid weight loss, encourage healthy habits, and improve overall health.

If you’re interested in trying the Slimming World diet, keep in mind that your success will depend on how committed you are to following the plan and attending meetings.