If you're looking for a quick fix, the Cambridge Diet is for you.
It involves eating (or drinking!) shakes, soups, porridge and bars all specially made by the Cambridge Diet team.
There are six different plans you can go on - a Cambridge Diet consultant helps you to decide which is best for you - but depending on your weight loss needs, you could be on as little as 440kcals a day!
The Cambridge Diet was launched back in the seventies by a man called Dr Alan Howard at Cambridge University (hence the name!) and since then over 25 million people have tried it.
How it works
The six diet plans range from 440kcals to 1,500kcals a day. The plans involve you either just eating the official Cambridge Diet food, or mixing in some low-calorie normal meals too.
The good news is that all the plans are nutritionally balanced - meaning they have the recommended daily allowance of vitamins and minerals. The diet is designed to put your body into a state of mild ketosis. Sounds scary, but what it actually means is that your body starts having to break down your fat for energy.
If you want to try out the diet, you have to get in touch with a Cambridge Weight Plan consultant, who will weigh and measure you, and decide which programme suits you best.
The shakes, soups and porridge come in handy little sachets that you mix with water, but aren't famed for being the tastiest meals out there.
A typical day
Your daily diet varies depending on which plan you're put on. Some of the plans can only be done for a few weeks or months, others can be done long term, but with each stage you come closer to a normal, long term diet.
Step one (415 - 615kcal daily)
This plan is called Sole Source, where you have three or four Cambridge Diet products a day, and that's it. Sole Source Plus is a different version of this step. For that plan, you have three Cambridge Diet products and one normal meal of around 200 calories, or four products and 200ml of skimmed milk.
Step two (810 kcals daily)
Three weight plan products, plus protein rich food such as skimmed milk and some vegetables.
Step three (1000 kcals daily)
Two diet products, milk, breakfast and salads for lunch and dinner.
Step four (1200 kcals daily)
Two diet products, skimmed milk and a calorie controlled lunch and dinner.
Step five (1500 kcals daily)
One diet product, breakfast, lunch, dinner and a snack. You'll be given meal suggestions.
This is the long-term, maintenance phase. You have one diet product a day, but will be given suggestions for a healthy, balanced diet.
The Cambridge Diet site is full of testimonies from people who have dropped from a dress size of 20 to 12 and even losing half of their body weight!
The weight loss can be sudden and quite dramatic. Plus, the meals are all nutritionally balanced so you can be sure you're getting all of the vitamins and minerals you need. Also, with the consultant helping you along, you'll know when you know you're in good hands.
There's a fair few side effects to the Cambridge Diet. Initially, you might have bad breath, a dry mouth, tiredness, dizziness, nausea and constipation (due to a lack of carbs and fibre). Replacing meals with shakes and soups can also be tricky if you don't like the taste, and it can be pretty anti-social.
TOWIE's Lauren Goodger went on the diet after she put on weight and was really happy with the results!
Find out more
Find out if you should go on the diet and get in touch with a consultant here.
Other diets to try...