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 there are some downsides (1, 2, 3).

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

Rating Score Breakdown
  • Overall score: 4
  • Fast weight loss: 3
  • Long-term weight loss: 3.75
  • Easy to follow: 4
  • Nutrition quality: 4.25
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 dietShare on Pinterest

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

Today, it continues to implement the original model of non-restrictive 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 and obsessing over calorie restriction (1).

Specifically, Slimming World promotes a style of eating called Food Optimizing that involves filling up on lean proteins, starches, fruits, and vegetables, adding in 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 (1).

The Slimming World program also provides weekly support groups online or in-person in certain areas, as well as ideas for developing exercise routines (1).

Summary Slimming World is a flexible eating plan designed to help you lose weight and get healthy through non-restrictive healthy eating, group support, and physical activity.

Anyone can get started with the Slimming World diet by signing up for the community online at their U.S. or U.K. websites.

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, including dairy foods, nuts, seeds, and whole grains.
  3. Enjoy a few “Syns.” Short for synergy, syns are occasional treats like 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 apps. There are no rules involving calorie counting or food restriction.

Members are also given 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 range from $40 for 3 months to $25 for 1 month. After signing up for an initial subscription, it costs $10 a month to continue (5).

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.

Summary The Slimming World diet involves following a flexible style of eating called Food Optimizing that doesn’t focus on calorie counting or restriction and instead encourages participating in weekly meetings and increasing your physical activity when ready.

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 (6, 7).

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).

Another study in close to 5,000 adults observed that participants who went to 20 of 24 Slimming World sessions over 6 months lost 19.6 pounds (8.9 kg) on average (8).

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, 9).

However, keep in mind that several of these studies were funded by Slimming World, which may have influenced results (1, 8, 9).

Nevertheless, the consistent results suggest that this diet may be an effective way to lose weight in a healthy way.

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

Summary Several studies indicate that following the Slimming World diet is effective for weight loss. Membership duration and group meeting attendance appear to be linked to the greatest weight loss.

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

One study 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 (3).

What’s more, over 80% of participants noted an improvement in their overall health (3).

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

Additionally, since Slimming World helps people lose weight, it may decrease the burden and lower the risk of obesity-related chronic conditions, such as type 2 diabetes, high blood pressure, and heart disease (10, 11).

Still, research on the effects of Slimming World on these conditions is lacking.

Finally, Slimming World may be a cost-effective method for treating overweight and obesity.

One study observed that referring people who were obese to Slimming World was one-third of the cost of treating obesity with popular weight loss medications like orlistat (12).

Summary Members of the Slimming World community have reported developing healthier habits and experiencing improvements in overall health aside from weight loss. The diet may also be a cost-effective method to treat and prevent overweight and obesity.

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

For one, achieving successful weight loss 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.

Preparing healthy Slimming World recipes may also be challenging for people with limited cooking skills and time. In addition, the monthly membership fees may be too expensive for some.

Finally, since Slimming World discourages calorie counting and doesn’t specify appropriate portion sizes for the program’s Free Foods, some people may overeat them.

Though Free Foods are satisfying, some can be high in calories and fairly low in nutrients, including potatoes and rice. Eating large portions of these foods may contribute to overconsumption, which may prevent weight loss.

Potatoes, rice, pasta, fruit, and other “free” starchy foods can also lead to blood sugar spikes and may be problematic for people with diabetes (13).

Summary It may be difficult for some people to adhere to the Slimming World program, especially those with limited time, income, and cooking skills. Furthermore, some people may overeat the program’s Free Foods, hindering their weight loss efforts.

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 (14):

  • 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, 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, which is explained in the materials provided to those who sign up for the program.

Some examples of these extras are (14):

  • 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, flax seeds, 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.

Summary The Slimming World diet focuses on eating mostly Free Foods that include lean proteins, starches, fruits, and vegetables, as well as smaller portions of Healthy Extras, such as dairy, whole grains, nuts, and seeds.

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

Members are encouraged to enjoy these Syns from time to time to satisfy cravings and feel less tempted to get off track, though portions depend on your individual needs and goals.

Syns include (14):

  • Sweets: donuts, cookies, cakes, candies, biscuits
  • Alcohol: beer, wine, vodka, gin, tequila, sugary mixed drinks
  • Sugary drinks: sodas, fruit juices, energy drinks
Summary While the Slimming World diet doesn’t restrict any foods, it suggests limiting sweets and alcohol to occasional indulgences.

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

Here is a sample three-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, and 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
Summary A sample menu of the Slimming World diet includes mostly lean proteins, filling starches, fruits, and vegetables, as well as some dairy products and healthy fats. Occasional sweet treats and alcohol are allowed as well.

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.