Carbohydrate-free diets are popular with Hollywood superstars, but are they a safe method of weight loss? Our Nutrition expert, David Swain, advises.

Raisingkids member's problem
My 16 yr-old is exercising a lot, and trying to lose a bit of weight. She has a fruit smoothie for breakfast, and a smoothie and sandwich for lunch, then eats whatever the rest of us are having for dinner.

She wants to try a carbohydrate-free diet - is this healthy? Please can you advise me on the best way she can lose weight without damaging herself?

David's advice
Thanks for this question. Firstly, I think it's important to determine whether your daughter really needs to lose weight. This can be done by comparing her weight and height on a growth chart - if you are unsure about how to do this ask the school nurse or your GP.

Presuming she does need to lose weight, the most effective way to achieve and maintain a healthy weight is through a combination of activity and healthy eating. Healthy eating meaning a varied and balanced diet limiting excessively high fat and sugary foods. I understand that there are a lot of conflicting messages about diets on the market, but it is important to remember that there are no 'wonder' diets or foods which cause weight loss.

I think one problem with your daughters current diet is that it relies too heavily on fruit smoothies which, even if they are nutritious, may become boring with time. In addition, too much of one foodstuff can often lead to an unbalanced diet.

With regards to low-carbohydrate diets you may well lose weight on this regimen because if you cut down on bread, pasta, rice, crisps and eat only meat, fish and vegetables you will tend to eat less overall. BUT you are likely to get bored with this diet and therefore slip or get too hungry as your diet will lack bulk. Furthermore, limiting carbohydrates causes the body to rely on fat or muscle for energy. This can create a by-product called ketones, causing fatigue and nausea. This is particularly dangerous for anyone with diabetes, heart or kidney problems.

For information on how to lose weight properly, visit the British Dietetic Association at www.bda.uk.com, or the British Nutrition Foundation at www.nutrition.org.uk.

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