A 2005 study by American scientists found that diners who ate from a bowl of soup that kept refilling would not only eat far more than normal, but they did not notice that they had eaten more, and did not feel more sated.

Most shoppers base their food choices on price rather than nutritional value, with lower socio-economic status consumers more likely to eat high energy-dense foods such as sugary drinks, said Marion Hetherington, a professor of biopsychology at the University of Leeds.

However, Jennie Brand-Miller, a professor at the University of Sydney's School of Molecular Bioscience, said low-fat diets may not in fact be best for our health.

"Low-fat dietary advice has not been helpful on a population level. It is consistently associated with weight regain. It does not reduce the risk of chronic disease," said Brand-Miller.

"We need to pay more importance to protein. Protein is satiating, and we've undervalued it. We need to pay more attention to the sources of carbohydrate -- we need to switch from high GI to low GI carbohydrates," she said.

At the heart of the obesity issue is the question of responsibility, and whether it's up to the consumers to look after their own needs, or industry to provide more healthy foods.

"In Britain, the public health responsibility has been an important initiative in the sense that companies will sign up, they will pledge to reduce the amount of calories in their food, to reduce the amount of salt," said Hetherington.

By lowering salt, sugar and calorie content of their foods independently, industry will not face competitive pressure caused by only some producers providing more healthy foods in the marketplace, she said.

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