The Cambridge diet is a calorie-controlled diet aimed at rapid weight loss. There is a strict regime to follow, starting as a 12-week, very low-calorie diet consisting of meal replacements in the form of shakes, soups and bars. It has been renamed as the 1:1 diet, as it also includes personal one-to-one support with a diet consultant to guide you through the different stages. While it may provide quick results in the short term, there are concerns that it is an extremely restrictive weight-loss plan that is unsustainable long term.


Visit our ‘All you need to know about diets’ page for recipes and more expert advice on weight loss, including low-GI and the Mediterranean diet’

How does the Cambridge diet work?

Put simply, the Cambridge diet works by significantly cutting calories. Meals are replaced with calorie-controlled products and total daily calorie intake gradually increases as you progress through the different stages of the diet over time. By significantly reducing calories, the diet works like a ketogenic diet; by putting the body into ketosis. In the absence of carbohydrates for energy, the body starts burning stored fat leading to a reduction in weight.

The Cambridge diet has evolved into the 1:1 diet with the addition of a ‘personalised consultant’ working with the dieter to create an individualised diet plan. This extra support provides accountability and has been shown to help increase success rates. Ingredients and meal replacement ideas are provided (at a cost), and you continue to see your consultant once a week for a review and to order more meals.

Focus is on a shake in a glass, being held by a female wearing sports gear and carrying a yoga mat

What can I eat on the Cambridge diet?

The diet follows six stages and total calories gradually increase from around 500 to 1200 kcal per day before the maintenance stage is reached. What you eat depends on the stage you’re in. You can expect to pay around £2.78 per meal replacement.

More like this
  • Stage 1 ‘Sole Source’: Eat 3-4 Cambridge diet meal replacements each day (consuming 400-600 calories for up to 12 weeks).
  • Stage 2: Eat 2 Cambridge diet meal replacements plus protein-rich foods, skimmed milk and some vegetables (consuming 800 calories a day).
  • Stage 3: Eat 2 Cambridge diet meal replacements plus skimmed milk, breakfast and salads for lunch and dinner (consuming 1,000 calories for 2 weeks).
  • Stage 4: Eat 2 Cambridge diet meal replacements plus skimmed milk, breakfast, lunch and dinner (continue for 2 weeks).
  • Stage 5: Eat 1 Cambridge diet meal replacement plus skimmed milk, breakfast, lunch, dinner and snack (continue for 2 weeks).
  • Maintenance: Eat a healthy diet plus your choice of Cambridge diet products approx. 1,200 calories per day (continue indefinitely).

There are 35 Cambridge diet products, including noodles, soups, porridge, shakes and bars. All are claimed to be nutritionally balanced and 200 calories or less. There are also recipes and ideas to include as you move towards the maintenance stage.

Read our article, How many calories should I eat, for more information.

How to follow the Cambridge diet

The first 12 weeks see quite a drastic approach to cutting calories which creates a very large calorie deficit for a short, intense period. This often brings about substantial weight loss.

Over the long term, more meals are introduced allowing for more flexibility. The diet consultants are there to support you through the plan and adapt it when required.

What is the evidence for the Cambridge diet?

The Cambridge diet approach has been included in the largest ever study of diabetes prevention. There is some published research to suggest that very low calorie diets (VLCD) like the Cambridge diet may help to manage Type 2 diabetes. While the very low calorie approach has been successful for those with type 2 diabetes, it’s not to say it is safe and effective for everyone.

A nutritionist’s view:

Strict calorie restriction may lead to quick weight loss, but it can pose a risk of nutrient deficiencies and bring other less desirable outcomes such as constipation, headaches and dizziness. The number of calories consumed on this diet are close to starvation levels, so are likely to flatline energy levels and deplete the immune system. Plus, it’s incredibly boring to be so restrictive in the foods you eat, which makes it fairly unsustainable in the long term and can negatively affect your relationship with food, your social life and mental well-being. There is a high risk that individuals will re-gain the weight once they return to a normal eating pattern, which can really undermine self-esteem.

Does the Cambridge diet work?

The plan is pretty simple but would definitely fall into the ‘fad diet’ category. Calorie restriction on this scale is not recommended (unless under the guidance of a health professional) and it seems a little ominous that success on this plan requires you to spend money buying Cambridge diet products.

Given the extreme calorie deficit, you are likely to see quite quick weight loss. However, it’s not a sustainable or healthy approach. Instead, consume balanced wholesome meals, plenty of water, take regular exercise and decent quality sleep as a more enjoyable and safer approach to healthy living.

Bowl of porridge with a glass flagon of milk in the background

Further reading:


How many calories will I burn?
Is a low-fat diet healthy?
What is a low-GI diet?
Top 10 health benefits of a vegan diet

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