Hidden Kilojoules

Low-fat products can have the same kilojoules as full-fat ones. Take "diet" yoghurts - some contain seven teaspoons of sugar and more kilojoules than a Caramello Koala.** Dr Tim Crowe, a dietitian, warns that some "reduced-fat" products are still high in fat; reduced-fat peanut butter is still almost 40 per cent fat.

Health halo

It pays to watch portion sizes. One study† shows that people eat up to 50 per cent more food if they think it's low fat. The same study also found that after eating diet products, people underestimated the kilojoules they consumed by up to 40 per cent. "Low fat is not a licence to overeat," says dietitian Susie Burrell.

Label lowdown

You wouldn't pop a pill without reading the back of the pack, so why don't you read food labels? In Australia, food must contain no more than three per cent fat to officially qualify as "low fat" - but this rule is voluntary.‡ As for words like "light", don't be fooled; this can simply relate to colour or flavour.

Snack attack

Sweet-tasting diet drinks may be low in "real" sugar, but they'll still keep your sweet tooth addicted. "Sweetness is like a drug," explains Burrell. "It switches on taste receptors in the brain that are looking for sweet substances - and the more you eat, the more they look for that next hit."

• Research by the bailey group.
  
  • choice magazine research, 2007.

†journal of marketing research, 2006, vol 43.
‡australia new zealand food authority code of practice