For any diet to work and for you to lose weight, you need to use up more energy than you take in from what you eat. To do this, your healthcare professional will recommend that you cut down on the amount of calories you take in and eat more healthily in the long term, and be more active to use more calories up. Any changes in diet should take into account your preferences, and fit in with healthy eating advice.
There are different types of diet that your healthcare professional may recommend. Some reduce the amount of energy or certain types of food you take in, and others allow a fixed amount of calories a day. On a low-calorie diet, your food provides only 800 to 1600 kcal a day. An energy deficit diet is where you take in less than your body needs just to stay the same weight (usually 600 kcal a day less). Or, you may be recommended a diet low in fat. Whatever diet you follow, your healthcare professional should make sure you get plenty of support while on the diet and afterwards to help you keep from putting weight that you lose back on.
Another type of diet you may be offered is a very-low-calorie diet. On these diets, your food provides only 800 kcal a day or less.
Your healthcare professional may recommend a very-low-calorie diet if you need to lose weight quickly (for example, if you are going to have joint replacement surgery), but these diets aren't used for routine weight loss. You should never follow a diet that provides only 800 kcal or less a day unless this is being closely monitored by your doctor.
If your healthcare professional does recommend that you follow a very-low-calorie diet this should not be for more than 12 weeks (either in one go or in shorter periods with breaks). You should also have other treatment and support to make sure you stay healthy while on the diet.
Before you start your very-low-calorie diet your healthcare professional should discuss the risks and benefits of the diet with you, and what happens when you finish the diet. You may be offered counselling and assessment to check if you have an eating disorder.
When you finish your diet you will get follow-up treatment to help prevent you putting weight back on, which can often happen after these diets. This will help you with any medical problems, getting used to a normal, balanced healthy diet again and ways to be more active.
Your healthcare professional may recommend changes in what your child eats, but this should always be with other treatment or support, such as help with becoming more active, and should be changes they can stick to. Any advice on food should fit in with general advice on healthy eating, and avoiding sweets and sugary drinks. Ideally, the whole family should make the same changes.
Questions to ask about your lifestyle and diet
Am I active enough, and can you give me some ideas about how to be more active?
How can I help my whole family to eat more healthily?
I am finding it very difficult to change what I eat. Is there anyone who can help me?
Are there any local support groups or organisations that can help me do something about my weight
How can I keep my weight stable and not put it back on once I have lost it?
How can I help an older person or a child change their lifestyle and lose weight?