What Foods Are Allowed on the Cambridge Diet? A Breakdown by Stage

October 20, 2025 •

4 min read

The Cambridge diet, rebranded in 2019 as The 1:1 Diet by Cambridge Weight Plan, operates on a staged approach where food allowances change significantly over time. The answer to the question, what foods are allowed on the Cambridge diet?, is entirely dependent on which of the six flexible steps you are following.

Quick Summary

The Cambridge diet, known as The 1:1 Diet, is a multi-stage weight loss program based primarily on branded meal replacements in its initial phase. As the dieter progresses through the structured steps, it gradually reintroduces a variety of conventional, healthy foods to support long-term weight management.

Key Points

Stage-Dependent Foods: The foods allowed are strictly determined by which of the diet's six steps you are following, evolving from total meal replacement to a balanced diet.
Initial Phase (Sole Source): The first, most restrictive phase involves consuming only proprietary Cambridge-branded meal replacements like shakes, soups, and bars.
Meal Replacement Products: The diet's core consists of specially formulated shakes, soups, porridges, smoothies, and bars, which are nutritionally complete and low-calorie.
Conventional Food Reintroduction: As you move to later stages, lean protein, vegetables, salads, and other conventional foods are gradually added back into the diet.
Maintenance Phase: The final step focuses on a healthy, balanced diet with the option to use one Cambridge product per day for continued support.
Professional Guidance is Key: Due to the very low-calorie nature of the initial stages, medical supervision or guidance from a qualified professional is often recommended.

Understanding the Staged Approach to Eating

The Cambridge diet, developed in the 1970s and now marketed as The 1:1 Diet, is a very low-calorie diet (VLCD) that focuses on rapid weight loss through a phased meal replacement system. The plan is supervised by a personal consultant who helps tailor the specific steps to your needs and goals. This structured approach means that the list of allowed foods evolves as you move from the initial restrictive steps towards a more conventional and sustainable eating pattern in the later stages. The diet's six steps progressively increase your daily calorie intake, moving from a sole dependence on branded products to a mix of products and regular meals.

Allowed Foods in the Initial Steps (Sole Source)

In the most restrictive phase, known as the 'Sole Source' or Step 1, you consume only Cambridge-branded meal replacements. This phase is typically kept to a maximum of 12 weeks and involves consuming 400-600 calories per day. These nutritionally complete products are designed to provide all the essential vitamins and minerals your body needs while operating on a significant calorie deficit.

The primary allowed foods during this phase are:

Meal Replacement Shakes: Available in many flavors, including chocolate, vanilla, banana, and strawberry.
Soups: Hearty options like chicken and mushroom, vegetable, and leek and potato.
Bars and Bites: Various sweet and savory snacks such as chocolate chewy bars, fruit and nut bars, and salted caramel bites.
Smoothies: Fruity options like blackcurrant & apple or strawberry & banana oat smoothies.
Porridge and Cereal: Warm breakfast options in flavors like golden syrup or mixed berry.
Savoury Meals: For later in the initial stages, options might include ready-to-eat pasta, rice, or curries.

Along with these products, ample fluid intake is essential, particularly water. Plain tea and coffee are also permitted.

The Reintroduction of Conventional Food

As you progress through the higher steps of the diet, regular, everyday food is gradually reintroduced, with calorie counts increasing to support your weight-loss journey. This is a critical transition period that teaches portion control and healthy eating habits.

Allowed Foods in Intermediate Steps (Steps 2-5)

Step 2 (800 calories): Two Cambridge products are consumed per day, along with one 200-calorie regular meal. This regular meal typically consists of lean protein sources and vegetables.
Step 3 (1,000 calories): Two Cambridge products are combined with a 150-calorie breakfast and a 400-calorie lunch or dinner, which often includes salads or other vegetable-rich dishes.
Step 4 (1,200 calories): The allowance increases to two Cambridge products, a 200-calorie breakfast, a 400-calorie main meal, and an additional 100-calorie bonus.
Step 5 (1,500 calories): You transition to a more traditional eating pattern with one Cambridge product and three regular meals, often including a snack.

The Maintenance Phase (Step 6)

The final stage is about long-term weight maintenance. This involves adopting a healthy, balanced diet of around 1,500 calories or more, with one Cambridge product per day if desired for convenience. The focus shifts to cooking from scratch, understanding portion sizes, and making sustainable lifestyle choices.

Comparison of Food Allowances by Stage


Feature	Step 1: Sole Source	Intermediate Steps (2-5)	Step 6: Maintenance
Diet Focus	Exclusive meal replacements	Gradual reintroduction of regular food	Healthy eating with optional products
Calorie Range	400-600 kcal	800-1500 kcal, increasing with each step	~1500+ kcal
Cambridge Products	3-4 products per day	1-3 products per day, decreasing over time	1 product per day (optional)
Conventional Food	None	Lean protein, vegetables, salads, skimmed milk	Balanced meals of regular, healthy food

The Importance of Consultation and the Risks of Extreme Restriction

While the Cambridge diet's structured nature provides clear guidelines, it is a very low-calorie approach, especially in the initial phases. Reputable sources caution that such extreme calorie restriction should be undertaken with professional guidance, especially for extended periods. Health experts, including registered nutritionists, have raised concerns about the long-term sustainability and potential side effects of VLCDs. These can include headaches, dizziness, fatigue, and potential nutrient deficiencies if not properly managed. Moreover, critics point out that the initial phases don't necessarily teach participants how to navigate a real-world food environment, increasing the risk of weight regain.

For a general overview of the diet and its stages, consult reliable health information resources, keeping in mind that professional medical advice is recommended before undertaking a VLCD program like The 1:1 Diet. For more details on the structured plan, you can refer to the overview provided by BBC Good Food.

Conclusion

In conclusion, the types of foods allowed on the Cambridge diet are meticulously controlled and depend entirely on which of the program's six steps you are following. The initial phases rely exclusively on a wide variety of proprietary meal replacement products such as shakes, soups, bars, and meals, designed to create a significant calorie deficit. As you progress, the diet gradually reintroduces conventional foods like lean protein and vegetables in controlled portions, with the final maintenance phase focusing on a balanced, healthy diet combined with optional use of the products. While this structured approach can lead to rapid weight loss, it is a restrictive plan and should be approached with caution and ideally under the guidance of a qualified consultant to manage health risks and ensure long-term, sustainable habits are developed.

Frequently Asked Questions

Since 2019, the Cambridge diet has been rebranded and is now known as The 1:1 Diet by Cambridge Weight Plan.

During the most restrictive phase (Step 1, 'Sole Source'), you can only consume 3-4 proprietary Cambridge/1:1 Diet meal replacement products and drink plenty of water.

Regular food is gradually reintroduced starting from Step 2, where you replace one product with a 200-calorie meal containing lean protein and vegetables.

The product range is extensive and includes shakes, soups, porridge, smoothies, bars, bites, and pre-packaged meals like pasta and curries.

Yes, water is strongly encouraged, but plain tea and coffee (without milk in the early stages) are also allowed.

The Cambridge diet, or The 1:1 Diet, is designed to be followed with the one-to-one support of a consultant who helps you choose your plan and provides weekly check-ins.

While the diet can lead to rapid weight loss initially, many experts caution that the early restrictive phases are not sustainable long-term. The diet transitions to a maintenance phase to promote healthier habits.