Healthy living * Weight loss

Low-fat crisps could make you fatter

Low-fat crisps could make you fatter Unexpected effect on body

We all love to eat crisps and sweets, but we also don't want to get any fatter. That's why clever manufacturers have developed whole ranges of "low-fat" versions of our favourite snacks.

But new research suggests that these "healthy" alternative treats may have the opposite effect.

Some low-fat crisps and other foods use fat substitutes such as the synthetic chemical olestra, which has zero calories and passes through the body undigested.

Scientists at Purdue University in the US investigated the effects of fat substitutes on weight gain by feeding low-fat Pringles to lab rats.

About the study

Half of the rats in the experiment were fed a high calorie diet, and the other half were given a low calorie diet. Each group was then sub-divided into two further groups. One sub-group in each group was given normal, high-fat Pringles, and the other sub-group was given a mixture of high-fat and low-fat Pringles.

They found that in the rats on the high-fat diet, the sub-group that ate both types of Pringles gained more weight and developed more fatty tissue than the rats that ate only the high-calorie chips. Even worse, these rats did not lose any weight when the crisps were removed from their diet.

Commenting on these results, study leader Susan E. Swithers said that "based on this data, a diet that is low in fat and calories might be a better strategy for weight loss than using fat substitutes."

Possible explanation

The researchers suggest that one possible reason for these results is that the presence of high-calorie fats and sugars in food is detected by the body (through the sweet or fatty taste and texture) and this triggers biological responses such as salivation, hormonal secretions and metabolic reactions.

Fat substitutes may trigger the same responses which then interfere with the way the body processes the food when the anticipated calories are not present. Although Swithers admitted that extrapolating these results from rats to humans is not easy, she pointed out that their biological responses to food are similar.

These results, reported in the journal Behavioural Neuroscience, build on similar results found by measuring the effects of saccharin and other artificial sweeteners on diet.

So it seems that the food manufacturers were not so clever after all, as Swithers explains: "Eating food which is naturally low in fat and calories may be a better route than relying on fat substitutes or artificial sweeteners."

This article was published on Thu 23 June 2011

Image © Ewa Walicka -

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