Created by a British company, the Slimming World diet is run by a weight loss organisation that runs over 5,000 weight loss classes across the UK every week. Our diet plan review explains how the Slimming World diet, also known as "food optimising", works.

The Slimming World diet is a calorie-restricted programme that includes in its diet meal plans and recipes many foods known as "free foods" which participants can eat as much of as they like. In addition, you are allowed four portions a day of higher calorie foods, or "healthy extras", which also provide plenty of fibre, vitamins and minerals. The Slimming World diet Food Optimising plan also divides days into "red" and "green" days.

On red days, free foods include the following:

White fish
Lean meats
Eggs
Most fruits and vegetables

Restricted red day "healthy extras" include:

Milk
Cheese
Bread
Grains
Beans
Potatoes
Dried fruits

On green days, free foods are:

Fruit and vegetables
Grains
Beans
Pasta
Tofu
Eggs

Green day "healthy extras" include:

Milk
Cheese
Bread
Dried fruits
Nuts and seeds
Meat
Fish

Although there isn't a formal exercise regime included in the programme, participants are encouraged to be active. If you exercise at the same time as following the weight loss plan you may find yourself making "hidden" progress, because fat is replaced by muscle, which actually weighs more than fat. Members of the programme are advised not to be discouraged if their weight doesn't appear to be going down for this reason. Instead of focusing on weight, they're encouraged to measure their bust and waist instead, so they can see change in their body shape.