Marie Claire is supported by its audience. When you purchase through links on our site, we may earn commission on some of the items you choose to buy.
It claims to help you lose weight, fast – but is it healthy or sustainable?
Important disclaimer here: you shouldn’t feel pressured to lose weight. Every body is different, will look different, and will have a different set point.
But, if you do want to lose a few pounds and are keen to read up on the Cambridge Diet, we wanted to make sure you were armed with expert-advice before trying anything new.
Let’s be clear here: The Cambridge Diet – now renamed the 1:1 diet – is an extreme weight-loss plan and, according to nutritionist Lauren Windas, is overly restrictive. “You’re putting your body into a very low-calorie deficit throughout much of the plan and entering starvation mode,” she shares.
Based around a range of bars, soups, and shakes, this diet plan is apparently cheaper than Weight Watchers, and faster than your average calorie-controlled diet. But does an expert advise it?
Here’s everything you need to know…
What is the Cambridge Diet?
Despite the name, the diet bears no relation to the Duchess of Cambridge, Kate Middleton, according to Windas. “The Cambridge Diet was invented in the 1960s by Alan Howard, a Nutritionist at Cambridge University, hence the name,” she shares. “Working in the Department of Medicine, he collaborated with a consultant at a local hospital, where they designed a low-calorie diet for morbidly obese patients. They later released this plan to the public in the 1980’s.”
The Cambridge Diet stipulates that regular consumption of low-calorie shakes, soups and snack bars. These claim they have been designed specifically for the program to fulfil all of your daily nutritional requirements under strict calorie guidelines, and further, that they can lead to immediate weight loss.
There are six variations of the Cambridge Diet plan. The steps range from Step 1 or ‘Sole Source’ (a very low-calorie diet where you solely eat the range of products provided) to Step 6 or ‘Maintenance’ (where you eat a healthy diet interspersed with meal replacements when necessary) depending on your time scale and target weight loss. But this diet is not to be entered into lightly.
A Cambridge Diet counsellor will follow your progress throughout, beginning with which variation to start with and some steps will even require written consent from your doctor.
How does the Cambridge Diet work?
Similar to the keto diet, The Cambridge Diet works by forcing your body into a state of ‘ketosis’.
This occurs when the body does not receive all of the calories it needs to function properly and so is forced to turn to fat stores in order to carry on going.
What are the pros of the Cambridge Diet?
According to the nutritionist, in the short-term, it can deliver quick results in terms of weight loss.
Plus, it’s fuss-free and convenient. “One of their consultants guides you, takes the thinking and planning away from you so it is easy to implement into your routine. It’s also convenient for those who are time-poor or suffer with portion control.”
Is the Cambridge Diet safe?
Initially, when the diet launched in the 1980s, the daily calorie count consisted of a dangerously low 330 kcals per day, shares Windas. “In recent years, this has been upped to 600 kcals per day, and can go up to 1500 calories in some steps of the plan,” she shares.
Nevertheless, you are still putting your body into a very low calorie deficit throughout much of the plan and entering starvation mode, she highlights.
“It’s important to know that there are much healthier ways to achieve your weight loss goal,” she stresses.
Further, because it’s a short-term diet, many people may struggle to keep the weight off long-term, she explains. “It can provide quick results; however, what do you do when the plan ends?,” she asks.
“It’s far from sustainable and doesn’t give you the learnings and tools to cement healthy habit changes whilst maintaining a healthy relationship with food.”
Not to mention it’s restrictive. “While the plan is not only low-calorie, it also involves consuming their specific meal replacement products which consist of shakes, smoothies and soups. Because the range is quite limited, those who follow the plan can easily become bored and feel deprived of the foods they love.”
Reported side effects of the diet are bad breath, thinning hair (in which case try one of our beauty editor-approved best shampoo for hair loss picks), nausea, dizziness and diarrhoea.
Does the Cambridge Diet work?
That’s the question people want the answer to the most, so it’s worth remembering that every body is different and so diets will work differently on every body. Plus, you can’t easily create this diet plan at home. If you do opt in, experts from the brand stress the importance of doing everything by the book.
There are six types to try including the weight plans you’ll be looking at:
- Sole Source: Eat 3-4 Cambridge Diet meal products each day (consuming 415-554 cals, lasting 1 week minimum/12 weeks maximum)
- Sole Source +: Eat 3 Cambridge Diet meal products and 200ml of skimmed milk each day (consuming 615 cals a day, lasting 1 week minimum/12 weeks maximum).
- Step 2: Eat 2 Cambridge Diet meal products plus protein-rich foods, skimmed milk and some vegetables (consuming 810 calories a day, lasting 1 week minimum).
- Step 3: Eat 2 Cambridge Diet meal products plus skimmed milk, breakfast and salads for lunch and dinner (consuming 1000 calories for 2 weeks).
- Step 4: Eat 2 Cambridge Diet meal products plus skimmed milk, breakfast, lunch and dinner (continue for 2 weeks).
- Step 5: Eat 1 Cambridge Diet meal product plus skimmed milk, breakfast, lunch, dinner and snack (continue for 2 weeks).
- Maintenance: Eat a healthy diet plus your choice of Cambridge Diet products (continue indefinitely).
A nutritionist’s verdict?
Bottom line: low-calorie diets like the Cambridge Diet are not sustainable. “They very much fit into the category of a diet fad, and if your ultimate goal is weight loss, there are much healthier means of losing weight than following this diet,” shares Windas.
Her advice? Work with a nutritionist and adopt a sensible calorie deficit, while making sure you’re building balanced plates full of your macronutrients (protein, carbohydrates and healthy fats). “This will provide you with unbiased, tailored and bespoke dietary advice to meet your personal health goals, and you achieve long lasting healthy change in not only body composition, but also in mind and general wellbeing,” she shares.