Britain would need to put a 20% "fat tax" on unhealthy food and drink to improve the numbers of people suffering diet-related conditions such as obesity and heart disease, medical experts warn.

Such a move should be combined with subsidies on healthy foods such as fruit and vegetables, say experts on bmj.com today.

Dr Oliver Mytton and colleagues at the University of Oxford released their findings ahead of the 65th World Health Assembly in Geneva on May 21 to May 26, where prevention and control of non-communicable diseases will be key issues for discussion.

The group said evidence suggests taxing a wide range of unhealthy foods is likely to result in greater health benefits than "narrow taxes" - although the strongest evidence related to taxing sugary drinks.

They said one American study found a 35% tax on sugar-sweetened drinks in a canteen led to a 26% decline in sales.

Studies extending VAT on unhealthy foods in the UK could cut up to 2,700 heart disease deaths a year, the researchers said.

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  • Hidden Fat Traps Lurking In Your Food

  • Dried Fruits

    Dried fruits are a great tasting snack, but beware they are often sprayed with a sugar solution before being packaged.

  • Sushi

    Sushi can come packed with mayonnaise (or mayo based sauces) as well as other sauces full of hidden calories.

  • Fruit Smoothies

    Not all smoothies have potential fat traps - ones made entirely from wholefood ingredients and fresh fruit, are packed with nutrients and vitamins. However, don't be fooled into thinking that all smoothies make a healthy drink. Many processed smoothies are so full of added sugars, syrup, additives and full-fat milk (and sometimes ice cream), that you'd be better off having a large milkshake from your local takeaway.

  • Vegetable Crisps

    It may seem like the healthier alternative to a packet of salt and vinegar crisps, but veggie crisps have the same fat content as ordinary crisps.

  • Frozen Yoghurt

    Frozen yoghurt is usually low in calories - but the sugar content can be sky high.

  • Chicken Wraps

    A tortilla wrap may contain carbohydrate than a slice of bread, but most pre-packed wraps are packed full of hidden fat traps, such as processed meat, mayonnaise and butter.

  • Processed Cereal

    Many cereals contain a host of different sweeteners to make them more tasty, so make sure you check the sugar content before piling it into your breakfast bowl.

  • Low Fat Muffins

    Choosing a low-fat muffin over a full fut version may seem like a clever move, but in reality, the snack can contain more sugar. This means that not only could your 'healthier' muffin contain more calories, it may be less filling too.

  • Gluten-Free

    Gluten-free aren't necessarily more healthy. Many gluten-free foods are processed and packaged, meaning they still have the fat traps other foods have.

  • Rice Cakes

    Rice cakes can be a low calorie snack - as long as you stick to plain and don't pile on the toppings.