Cambridge Diet – Principles, Effects, Meal Plan

The Cambridge Diet, now also known as The 1:1 Diet, is a very low-calorie approach to weight loss based on pre-packaged meal replacements. It's a popular method used by people around the world looking to lose weight quickly. But is it actually healthy? What are the rules of the Cambridge Diet, what kind of results does it offer, and what does a typical daily menu look like?

What is the Cambridge diet?

The Cambridge Diet is a structured weight loss program developed in the 1960s by Dr. Alan Howard from the University of Cambridge and Dr. Ian McLean-Baird. They were searching for an effective solution to fight obesity and created this plan as a response.

Since 2019, the plan has been rebranded as The 1:1 Diet by Cambridge Weight Plan. It falls under the category of VLCDs (very low-calorie diets). The program is divided into phases and is based mainly on replacing regular meals with ready-made products that can only be purchased through authorized consultants.

The goal of this diet is rapid weight loss by drastically reducing calorie intake and limiting carbs and fats. This puts the body into a state of ketosis, which encourages the use of stored fat for energy.

Versions of the Cambridge diet

There are two main versions:

• The British version
• The American version

Both are high-protein, low-calorie diets, but they follow slightly different phases.

British Cambridge diet

• Preparation phase: you gradually lower your calorie intake for 7-10 days before starting the program.
• First phase: you consume only Cambridge-branded meal replacements, about 500 calories per day, for 4 weeks.
• Stabilization phase: calorie intake increases to around 1,000-1,500 calories daily. Some meal replacements are swapped for regular meals.
• Maintenance phase: you consume about 1,500 calories per day, replacing one regular meal with a Cambridge product to maintain your weight.

American Cambridge diet

The U.S. version offers five structured programs:

• Regular program: drink 10 glasses of water, eat 3 Cambridge meals (820 calories total), plus one regular 400-calorie meal. Can be followed long term. Average weight loss: 2-5 lbs/week.
• Fast start: similar to the British version, followed for up to two weeks.
• Large weight loss program: designed for people looking to lose more than 33 lbs and under medical supervision. Starts like the British version, then switches to the Regular Program for the final 15 lbs.
• Stabilization program: gradually reintroduces traditional meals alongside Cambridge products to maintain weight.
• New habits plan: after reaching your target weight, you continue replacing one regular meal daily with a Cambridge product to keep results stable.

Cambridge diet - 6 stages

The diet is broken down into six phases (also called "steps"), and calorie intake increases with each step. The timeline and specific plan are usually personalized by a Cambridge consultant.

Here's the general breakdown:

• Step 1: Only Cambridge meal replacements - 4 products per day, max 800 calories total.
• Step 2: 3 Cambridge meals (600 calories) + 1 small regular meal (~200 calories).
• Step 3: Regular breakfast (150 cal), regular lunch (400 cal), 2 Cambridge products + 125 ml of 2% milk. Total: ~1,000 calories.
• Step 4: Breakfast (300 cal), lunch (400 cal), 2 Cambridge products + 100 ml of 2% milk. Total: ~1,200 calories.
• Step 5: Traditional breakfast (300 cal), lunch (500 cal), dinner (400 cal), 1 Cambridge product + 100 ml of 2% milk. Total: ~1,500 calories.
• Step 6: Regular diet of ~1,500 calories per day, with one meal replaced by a Cambridge product.

What foods are allowed?

Cambridge meals were first used in hospitals. Over time, the products became commercially available. By 1980, they were sold in the U.S., then the UK, Germany, France, Scandinavia, and later in Eastern Europe, including Poland.

Allowed items include:

• Meal replacement shakes and soups
• Smoothies, porridges, and bars
• Ready-to-eat pasta, rice, cookies, or pancakes (depending on location)

You’re allowed to drink water, tea, and coffee, but water is strongly encouraged. As you progress, small amounts of regular food are reintroduced, but calorie intake should be monitored closely.

Sample Cambridge diet meal plans

Step 1 Sample Menu (only Cambridge products)

• Meal 1: Fruit-flavored oatmeal
• Meal 2: Blackcurrant smoothie
• Meal 3: Cheese-flavored pasta
• Meal 4: Oriental soup

Step 5 Sample Menu (three regular meals + one Cambridge product)

• Breakfast: scrambled eggs (2 eggs) with tomato and chives, 1 slice of whole-grain bread with butter, black coffee
• Snack: Cambridge nut bar + water
• Lunch: tomato soup with rice and chicken breast + water
• Drink: 100 ml of 2% milk
• Dinner: tuna salad with arugula, cherry tomatoes, and avocado + 1 slice of whole-grain bread with butter, black tea

Results of the Cambridge Diet - is it safe?

The Cambridge Diet is straightforward and can lead to significant short-term weight loss – up to 33 pounds (15 kg) in a month. It's time-saving and doesn't require cooking skills in early stages, which adds to its appeal.

However, that’s where most of the benefits stop.

This plan is classified as a very low-calorie diet (VLCD). Experts recommend VLCDs only for short-term use (1-3 weeks) in extreme cases (e.g. before surgery), and always under medical supervision.

But Cambridge products are sold by non-medical consultants, who aren't qualified to assess health conditions or safely guide long-term dieting. This raises concerns.

Risks and drawbacks of the Cambridge diet

• Nutritional deficiencies due to limited food variety
• Dependency on pre-packaged products
• Disruption of social eating habits and relationships
• Harmful mindset toward food and eating
• Fatigue, brain fog, irritability from low calorie intake
• Digestive issues, headaches, hormonal imbalance
• Slower metabolism and lowered immunity
• Risk of yo-yo effect with rapid weight loss
• High cost – around $75 per week for products

Final thoughts - is the Cambridge diet worth it?

In short, no.

While it promises fast results, the Cambridge Diet comes with serious trade-offs – from health risks to financial costs. It's not sustainable, and it doesn't teach healthy eating habits. Most importantly, it’s not a safe long-term solution.

The healthiest way to lose weight is through a personalized, well-balanced diet designed by a qualified dietitian. This includes creating a modest calorie deficit, staying hydrated, and adding regular physical activity to your routine.

There’s no shortcut to lasting results – but with the right support, it's absolutely achievable.

Bibliography:

1. https://pubmed.ncbi.nlm.nih.gov/6748185/
2. https://dietsinreview.com/diets/Cambridge_Diet/3
3. https://journals.viamedica.pl/eoizpm/article/view/25924
4. "The Cambridge Diet: A Manual for Practitioners" J. Marks, A.N Howard, 2012