I'd never thought about this before, but I've never actually mentioned that you don't have to be as strict as I am on the Cambridge Diet. I have only ever done Sole Source and Add-a-Meal. Now I'm coming up to maintenance I shall be going up the steps, but you don't have to do it this way. Some people start off on the 1000 cals and stay on it to lose weight, or they work their way down slowly to Sole Source. These are the options anyway:-

Step 1 - Sole Source - 415-554 calories. This consists of 3-4 Cambridge Diets (bars,soups or shakes) depending on your height, only black coffe or tea and water. Also included in this step is Add-A-Meal(after 4 weeks of Sole Source). This is 415-510 calories or 548 - 640 calories and includes 3-4 Cambridge diets plus a small amount of protein and vegetables. This is for one week following 4 weeks of Sole Source or 2 weeks as a maintenance Step.
This is for anyone who is overweight with at least 1 stone to lose.

Step 2 - 790 - 790 calories. This is 3 Cambridge Diets plus skimmed milk, protein (more than add-a-meal) and green and white vegetables.
This is for anyone who has a BMI of 25 or more, anyone preparing for weight loss on Sole Source, anyone who needs to eat on social occasions who could not therefore use SS or anyone who has lost weight with SS, used Add-A-Meal and is on the stabilisation programme.

Step 3 - 1000 - 1000 calories. This is 2 cambridge diets plus skimmed milk, 150cal breakfast, green salad for lunch, 460cal dinner + fruit.
This is for anyone who is overweight and prefers a more gradual weight loss programme, anyone who finds it impossible to avoid conventional eating, anyone who is working through maintenance or anyone who is preparing for weight loss on a lower step. This applies to Step 4 and 5.

Step 4 - 1200 - 1200calories. This is 1 Cambridge diet, skimmed milk plus a 250 or 150 calorie breakfast, 200 or 300cal lunch plus a Cambridge diet and a 370cal dinner plus fruit for dessert.

Step 5 - 1500 - 1500cal - 300cal breakfast + skimmed milk and a Cambridge Diet, 350cal Lunch plus 50cal fruit, 100cal snack, 350cal dinner plus 150cal dessert.