The Cambridge Diet Plan: A Comprehensive Guide for Beginners

The Cambridge Diet was created by Dr. Alan Howard in 1970. He worked for Cambridge University, in the Dunn Nutrition Laboratory, as a biochemist. The idea for the diet came together with a colleague of his, Dr. Ian Mclean-Baird.

Dr. Mclean-Baird worked as a consultant for a local hospital. They joined forces to create what they believed to be the “perfect diet”. While the idea came into fruition in 1970, they didn’t perfect it or market it until 1984. The diet was launched in the UK and quickly became known as a restrictive diet but yields results quickly. Originally, it was marketed and designed as a low-calorie diet for morbidly obese people.

The diet doesn’t go by its original name any longer. Now, it’s commonly referred to as the 1:1 Diet by Cambridge Weight Plan. The diet advocates for the consumption of low-calorie foods, shakes, soups, and snacks that fulfill your daily dietary needs, while promoting significant weight loss.

The diet has six variations of the plan that take you from the beginning where you’re heavily restricted, to a maintenance plan. Keep in mind this diet isn’t for the faint of heart and will require strict discipline to keep at it. It may come with health issues too, more on that below.

What is the Cambridge Diet?

What is the Cambridge Diet?

The Cambridge Diet or the 1:1 Diet was designed for morbidly obese patients to return to a normal, healthy weight. Now, dieters of all ranges can participate in the program. Unlike many diets where you just follow a set nutritional plan, the Cambridge Diet requires you to meet with a consultant. You simply enter your postcode and find the closest consultant to you. Consultants use various social media channels too.

At your first meeting with your consultant, they will choose the best plan for you based on your weight loss goals and nutritional needs. Your consultant doesn’t just set a plan and leave you alone to work on yourself. They’re with you every step of the way. They’ll act as a guide and coach to keep you on track and monitor your progress.

Many people prefer the Cambridge Diet for the convenience and consultants. The consultants decide everything for you, including your portions. Those who struggle with portion control and have busy schedules benefit from them. You don’t have to think about your next meal or how much is too much.

The plan has six steps total with four stages. Most dieters start at step one, but the starting point isn’t the same for everyone. Your consultant will tell you which step you should begin with.

The Cambridge Diet doesn’t aim to put those in ketosis but sometimes it happens naturally. The lack of carbohydrates in the meal replacements and reduction of calories may cause it to kick in. When this happens, your body begins to use your fat stores as a source of fuel. Some dieters will lose weight quickly in the short-term. 

Steps of the Cambridge Diet 

Steps of the Cambridge Diet

The diet has two major plans Sole Source and Sole Source +. This is commonly where your first step begins and will determine how many of the Cambridge meals you consume and calories per day. Your height, weight, and gender will factor in where you start out on the program.

Sole Source is designed for those that need time to control their temptations of conventional foods, your height is under 5’7, and you need to lose a lot of weight. However, these conditions don’t always apply. For example, your consultant may suggest the Sole Source + plan regardless of your gender, weight, or height.

Sole Source + dieters are typically men, women with a 5’7 height or higher, and provides more flexibility. On a Sole Source + plan, dieters may have three Cambridge meals and a 200-calorie meal from a list of recipes provided to you by your consultant. Alternatively, you may have four Cambridge meals plus 200ml of skimmed milk. Regardless of your height or gender, this version doesn’t change.

  1. Total Diet Replacement Step – Steps 1a and 1b are the Sole Source and the Sole Source +. Both plans allow for 2.25 litres of liquid. You can have tea, herbal tea, coffee, mineral water, or sparkling water.

The 1a plan starts at 800 calories per day and the Cambridge meals are your sole source of nutrition. People commonly don’t extend past three weeks on this plan but up to 12 is allowed. You’ll have three (four depending on height, weight, and gender) meal replacements and fluids.

The 1b plan allows for 800 calories per day with 200 calories coming from conventional foods. Like plan 1a, you get to consume the same amount of liquids.

  1. Step Two: 800 Calories Per Day – This step of the plan allows for more flexibility and a higher calorie level than step one. Those best suited for this step include: 
  • Anyone above a BMI of 20 without a medical condition
  • Those who can’t consume a lower calorie diet
  • Those who want to prepare for a Sole Source plan
  • Anyone that has lost weight on Step One and is continuing with the program.

If you have a BMI over 50, you can’t join Step Two until they’ve spent time on a higher calorie plan first. Your consultant will guide you when it’s time for you to switch.

In this step, your consultant will guide you to the best food choices. Typically, you’re allowed three Cambridge products, 150 calories for breakfast, 200 calories for dinner, and 150ml of skimmed milk. You also get up to 2.25 litres of fluids throughout the day like in Step One. This step lasts for a minimum of one week but can last up to three weeks or longer.

  1. Step Three: 1,000 Calories Per Day – This step of the program adds fruits and carbs to the set calories in Step Two. This step is sometimes a starting point for those who want to lose weight gradually or they can’t avoid conventional foods. You’re allowed two Cambridge meals and regular meal options. Your consultant will help you choose which is best. You can have 2.25 litres of liquids and can include 0 calorie drinks too. Ideally, you’ll stay on this step for one or two weeks.

  2. Step Four: 1,200 Calories Per Day – On Step Four, you’ll include more conventional foods to your daily meals. It might become a starting point for those who want to lose weight slowly, need conventional meals, or take certain medications that forbid low-calorie diets. This step doesn’t have a set timeframe. You can stick with it if you like but you must stay on it for at least two weeks before you move to Step Five. Your consultant will help guide you through meals and prep work. You’ll have two Cambridge meals with the rest of your calories from conventional food.

  3. Step Five: 1,500 Calories Per Day – This meal plan almost removes the Cambridge meals. You only need to consume one per day and the rest comes from conventional foods with a snack. This plan is designed for those that are near Step Six, those who want to lose weight slowly, or those who want to continue weight loss. You must continue this step for up to two weeks before you can move on to Step Six. Realistically, you can continue this step for as long as you want. 

  4. Maintenance – Congratulations! You’ve reached your goal weight! Now, you want to keep it off! Many people often go back to their old eating habits and end up at square one again. This part of the plan is meant to keep your weight stable through two stages called stabilization and long-term weight maintenance. You can have a normal, healthy diet with a Cambridge product or none.

Stabilization gradually reintroduces different foods without weight gain. You’ll do this step for up to two weeks or until you keep your weight stable. Then, you can proceed to the next stage. Your consultant will let you know when it’s time to make the switch.

Long-term weight maintenance refers to your weight stabilizing at one of the steps for at least two weeks. You’ll know which calorie level your body best responds with to maintain your weight. You’ll have reintroduced foods, learned portion control, and temptation avoidance. At any time, you can reach out to your consultant for tips or if you feel you can’t keep up.

What Do You Eat on the Cambridge Diet?

What you eat on the Cambridge Diet will vary based on where you are in the plan. In general, the meal replacements have a range of meals and some snacks. For example, they have a variety of different meals, shakes, smoothies, breakfast options, and snacks. You can even try different flavored water options.


  • Chocolate
  • Vanilla
  • Chocolate mint
  • Banana
  • Strawberry


  • Cherry with strawberries
  • Blackcurrant with apple
  • Strawberry and banana oat

Breakfast Porridge and Shake Options

  • Golden syrup
  • Original
  • Mixed berry
  • Apples and cinnamon
  • Chocolate (Shake-N-Go)
  • Latte (Shake-N-Go)


  • Potato and leek
  • Goulash
  • Chicken with mushroom
  • Oriental chili

Dinner Options

  • Spaghetti Bolognese
  • Thai green with curry noodles
  • Chicken tikka curry
  • Green pesto pasta
  • Cottage Pie
  • Macaroni and Cheese
  • Vegetable soup with croutons


  • Dark chocolate ginger
  • Banoffee
  • Toffee chewy
  • Strawberry and apple
  • Peanut crispy
  • Lemon crunch
  • Orange fusion
  • Mint crunch
  • Cherry Bakewell
  • Chocolate chewy
  • Chocolate mint bites
  • Salted caramel bites

Flavored Water/Mousse Mix

  • Raspberry and elderberry
  • Pineapple
  • Orange
  • Lemon and lime
  • Golden vegetable
  • Mix-A-Mousse

In addition to the Cambridge meals, you can have conventional foods too. The only difference is you will have learned to portion your meals correctly and choose healthier options instead of processed meals and pizzas. Not much is restricted once you start to reintroduce foods so long as it’s healthy and not junk food.

You may wonder what the replacement foods, shakes, and smoothies taste like. After thorough research, we couldn’t find any negative complaints about them. The only complaints found were about the latte flavor of the shake and the potato and leek soup. Many found both flavors not necessarily bad, but very strong. If you’re not a fan or new to the soup and latte, you may have trouble consuming it.

Overall, the replacements are seemingly enjoyed by dieters. The oriental chili and smoothies were raved about by several dieters. Many of the dieters lamented about the lack of soup options. It’s a staple each day yet there’s not much variety like with the other replacements. 

What Can I Eat on Cambridge Diet Step 1?

What Can I Eat on Cambridge Diet Step 1?
On Step One, dieters typically don’t eat any conventional foods unless on the 1b plan. Both plans will require dieters to eat food replacement meals created by Cambridge. These meal replacements are low-calorie but contain the daily nutrients your body needs to survive. Depending on the plan, your weight, height, and gender, the number of meals you consume will vary.

Most on Step One consume around three to four meal replacements per day. As you progress in the steps, you’ll consume less of the meal replacements and more conventional foods. Those who start in different stages of the plan may consume anywhere from one to three meals or a snack per day.

What Can’t You Eat on the Cambridge Diet?

In terms of restrictions, most foods are allowed in the diet once you reach steps three to six. Your daily diet is configured with your consultant, and they will tell you what options you can and can’t have. Typically, the only foods/drinks you can’t have are junk foods, alcohol, or processed foods.

On the first step of the plan, you won’t be able to have any food except the Cambridge meals, milk, alcohol, diet drinks, or chewing gum. Throughout the diet, you won’t consume any alcohol or poor food choices and will opt for healthy meals instead. For example, you might have grilled chicken with steamed veggies as your dinner instead of fried chicken with mashed potatoes. It’s all about making healthier choices, so you don’t regain weight.

It should be noted, if you plan to complete the diet then go back to your old habits of bad food and alcohol, you will regain the weight. You don’t have to stick to the maintenance calories, but if you start overeating and making poor decisions, it will show. The last thing you want to do is drop down to your goal weight, then regain it all back over pizza and nights partying.

How Much Does the Cambridge Weight Plan Cost?

How Much Does the Cambridge Weight Plan Cost?

How much does Cambridge Diet cost? The price will vary based on a few factors. Consultants charge based on their fees plus the cost of food. For the diet itself, the meal products cost about £2.63/€3.03 per meal. How much does the Cambridge Diet cost a week? On average with consuming three Cambridge meals, the diet will cost around £55.23/€63.51 with a weekly consultant meeting.

Depending on where you start in the program will determine the cost too. Some people skip steps and only need one or two meals a week. Others may have the Sole Source program that requires four meals per day, which changes the price. Your consultant will be upfront and honest with you about any costs you can occur.

Typically, the plan has found people spend more per week on alcohol than they do on the plan. However, those that struggle week to week or live paycheck-to-paycheck might not be able to afford this cost on a weekly basis as they move up in the program. Those that start at different stages won’t have as much of a problem.

How Much Weight Can You Lose in a Month on Cambridge Diet?

How Much Weight Can You Lose in a Month on Cambridge Diet?

The amount of weight you lose will vary. The diet itself is famous for the fast results within the first few Steps. The original diet estimated you lose around a stone (14lbs) in one month. However, those on the new version of the plan report much higher weight loss.

Realistically, no one can predict how much weight you can lose in 12 weeks on the Cambridge Diet or at all. This is because each person has their own goals and starting points. Some research conducted by the diet found people lose around 10 kilograms (two stones, 28lbs) over 12 weeks.

Why the Cambridge Diet is Bad for You?

Why the Cambridge Diet is Bad for You?

Initially, when the diet first emerged, it has a severely low-calorie count at 330 max. You had to get a doctor’s permission and supervision just to be on the diet. Now, the diet starts at around 600-800 calories a day and can reach up to 1,500 calories based on where you are in the program. Some consultants will ask for a doctor’s note before you can take place in the lower-calorie steps. Unfortunately, that low number of calories is still dangerous. You basically put your body into starvation mode. There are much healthier ways you can reach your weight loss goal.

The Cambridge diet is a short-term weight loss plan. Short-term you’re able to lose a lot of weight but keeping it off long-term is a struggle. Many people often yo-yo diet because they don’t keep the weight loss off. The ketosis that follows the plan goes away once you stop it or add more carbs. For many, they experience weight gain quickly when the diet ends.

The restrictiveness of the plan doesn’t help either. The plan isn’t just low-calorie. It involves their brand of meal replacement shakes, smoothies, snacks, and soups. You don’t have a wide variety as you do with a standard diet. This can cause boredom or upset when you can’t enjoy many healthy foods that you used to.

Dieters often report illness on the diet too. Some symptoms include nausea, dizziness, hair loss and thinning, bad breath, and diarrhea. 

Side Effects of the Cambridge Diet

Side Effects of the Cambridge Diet

There are a few side effects that can occur with the Cambridge Diet. Some of them are minor but others are serious and can be life-threatening if not treated. The Cambridge Diet restricts calories and calorie restriction has been under controversy for decades. Most nutritionists and doctors won’t recommend under 1,200 calories per day and the Cambridge Diet drops as low as 800 calories. This diet, in the early phases of the program, is considered a starvation diet.

Ketosis is something that can occur on the Cambridge Diet. The diet itself doesn’t recommend low-carbs, just low-calories. However, it can unintentionally trigger ketosis. Ketosis is when the body uses fat stores instead of calories and carbohydrates for fuel. We all know keto diets have many health benefits but do have some negatives too.

Ketosis can stress the kidneys and cause kidney stones. This can be avoided if you follow a diet that doesn’t consume large amounts of protein or protein only. Keto flu happens with many keto dieters. This can bring on cluster symptoms like headaches, brain fog, fatigue, muscle pains, nausea, and diarrhea. These symptoms don’t last forever and usually subside after the first two to three weeks.

Bad breath has been noticed on the Cambridge Diet but not by all dieters. Dieters that end up in ketosis experience this more. Bad breath occurs when your body enters ketosis. It means your ketone levels are elevated. This side effect shouldn’t last for more than a few weeks.

Constipation is a common side effect of the Cambridge Diet. You’re cutting your calories, so you’re naturally not taking in much food. Many Cambridge Dieters often fall into ketosis which causes constipation too. Constipation occurs from the lack of low-fiber or no fiber foods and a lack of water.

Another potential and dangerous side effect of the Cambridge Diet is gallstones. When a person drastically cuts their caloric intake, they increase their risk to develop gallstones. In some cases, gallstones go away on their own. Other times, you’ll need surgery. Those who have a family history of gallbladder issues or bile duct problems shouldn’t attempt any low-calorie diet without a doctor’s supervision or permission.

Some people experience minor symptoms like cold sensations, gas, and tiredness. The cold sensations occur naturally with a low-calorie diet. This is an indicator that you aren’t getting enough calories to create heat for the body.

Gas has been reported with those on the Cambridge Diet. Dieters believe it comes from the Cambridge Weight Plan products. The products have ingredients in them known to cause gas, bloating, and diarrhea. As the plan progresses and people wean off the products, they notice this side effect improves.

Tiredness is heavily reported. This can come from a combination of issues. Tiredness can be a symptom of ketosis but also from the lack of calories. Keep in mind that a low-calorie diet can cause sleep issues too, which may cause insulin resistance and weight gain.

All low-calorie diets face other side effects like hair loss, inability to become pregnant (until a healthy weight and diet are reached, and mood swings.

Cambridge Diet Sample Menu

Cambridge Diet Sample Menu

Step One

Original Porridge meal replacement.

Oriental Chili soup meal replacement (200 calorie conventional food meal of protein and veggies or skimmed milk for plan 1b)

Green pesto pasta meal replacement.

Step Two

Cherry and Strawberry smoothie replacement meal (150 calorie breakfast) with 150ml skimmed milk.

Goulash meal replacement.

200-calorie dinner of protein-rich food with vegetables like turkey and yams.

Step Three

Mixed berry porridge meal replacement with 150ml skimmed milk.

Salad for lunch with chicken and mushroom soup meal replacement.

Salad with spaghetti Bolognese meal replacement.

Step Four

150 or 250-calorie breakfast with 150ml skimmed milk.

200 calorie or 300-calorie lunch like a salad with roasted tomato soup and a roll filled with cottage cheese.

300-calorie dinner like grilled chicken with vegetables and rice.

You can use two additional Cambridge Weight Plan products to fill the remaining calories like a shake or water flavoring.

Step Five

300-calorie breakfast like eggs and toast with 150ml of skimmed milk.

350-calorie lunch with 50-calorie fruit. For example, avocado, tomato, and chicken sandwich with an orange.

350-calorie dinner with 150-calorie dessert and 150ml of skimmed milk. For example, turkey, corn, and sundried tomato wraps with cinnamon crisps in yogurt with fresh blackberries. 

For this step, you can use one Cambridge product of your choice.

Step Six

Step Six will vary for some people. You will have a consultation with your consultant, and they will discuss with you’re the best food plan for you. The goal is to keep the weight off that you lost. They will help you reintroduce foods slowly. If you continue to maintain your weight, you won’t have to restart the program or stop the re-introduction of new foods. 

Tips to Remember on the Cambridge Diet 

Tips to Remember on the Cambridge Diet

The Cambridge Diet requires a lot of liquids. You only get about 60% of your water intake from food. It’s important you continue to drink water throughout the day to stay healthy. This diet recommends at least 2.25 litres of liquid a day. Those who have experienced the diet recommend drinking more.

Drink herbal tea and fruit tea. You already know you must drink plenty of fluids. This will add to your liquid consumption and include a few benefits. For example, chamomile tea can help you get a good night’s sleep. Peppermint tea will help with some side effects felt on the diet like constipation and gas.

Sleep is important regardless of your diet. However, on this diet, you will get tired easily for the first few weeks. You aren’t consuming as much food, so this is completely normal. When you’re tired, you tend to get cravings and hungrier. The more sleep you get, the more refreshed and alert you’ll feel.

Eat your green veggies. We all know green veggies are extremely healthy. On the Cambridge Diet, you’ll frequently eat salads or have a side of steamed vegetables. The darker and leafy green vegetables are high in nutrition and provide low calories. You can snack on as much as you want for your lunch or with your dinner to keep you fuller longer.

Final Thoughts

Final Thoughts

The Cambridge Diet was a popular diet when it first arrived at the diet scene. It helped morbidly obese patients learn to eat properly and help reverse of their health conditions. It has been shown to help those manage conditions like diabetes, osteoarthritis, sleep apnea, and heart conditions. The diet will provide you with weight loss. However, the question of health comes into play.

Dieters praise this program and say the benefits outweigh the risks. Medical professionals believe otherwise. They consider the Cambridge Diet a “fad” diet and that it’s dangerous. The “consultants” of the program aren’t medical professionals, yet you seek their advice on what you should and shouldn’t eat. One would say it’s no different than a friend saying “Hey, try this. It helped me!” and supporting them through their weight loss journey. The major difference is they get paid to promote this diet and help you. They also don’t have the proper training to recommend healthy options to you.

The diet itself requires you to eat few calories for weeks at a time which will naturally help you lose weight but comes with some negative side effects and sends your body into starvation mode. Some side effects like headaches, dizziness, and tiredness are caused by the lack of food.

The diet claims you will get all the nutrition you need from the meal replacements but they’re low in calories too. It’s also severely low enough in calories that a doctor sometimes must approve and monitor you while you’re on it. It’s not a diet you should attempt to try on your own unless you’re trying out Step Four or Five as it offers more wiggle room and a higher calorie content per day.

Start working on your weight loss goals

How would you like it if you

✓ Could be less dissatisfied with your body?
✓ Spend less time on your body and be able to do what you really care about?
✓ Learn to deal with that voice in your head?
✓ Stop letting your body image determine your day and emotions?
✓ Really change your relationship with food?
✓ Learn to appreciate your body, which will make you take better care of it?