The question: Do diet foods make you fatter?

Ian Sample: Eating more diet foods might not be such a problem if it wasn't for a pitfall in labelling. Food labelled as "low fat" is not necessarily low in calories, because manufacturers often just swap fat for sugar as a marketing trick.

If diet snacks and drinks fill up your shopping basket, the chances are you already have an eye on your waistline, which is a polite way of repeating Paris Hilton's famous observation that "Diet Coke is just for fat people."

But earlier this week, scientists in Alberta, Canada, reported that low-calorie foods might actively trigger overeating in children, putting them at risk of obesity. The warning followed experiments on rats that suggested only older animals could rely on their taste buds to tell them when they had eaten enough. Younger animals kept eating for much longer.

The picture for humans is different though. Children up to the age of five are exceptional at controlling their calorie intake, and know when they have had enough. The knack diminishes as we get older. That said, countless studies have shown that if you give people diet snacks they are likely to eat more than they would have done otherwise - probably because they feel less guilty.

Last year, researchers at Cornell University in New York dropped into cinemas, holiday camps and people's homes and gave them boxes of chocolates. Half the boxes were marked low fat, although the contents were identical to the others. They found people scoffed a third more of the chocolates they thought were low fat.

Eating more diet foods might not be such a problem if it wasn't for a pitfall in labelling. Food labelled as "low fat" is not necessarily low in calories, because manufacturers often just swap fat for sugar as a marketing trick. In the Cornell study, the researchers worked out that if the chocolates had really been low fat, people would still have eaten 28% more calories. "People feel they can have more if it's labelled low fat," says Dr Beckie Lang at the Medical Research Council's Nutrition Research Centre in Cambridge.


Ian Sample

The GuardianTramp

Related Content

Never say diet?

Losing weight could increase the risk of dying young, we are told. Margaret McCartney unravels the latest confusing health message.

Margaret McCartney

28, Jun, 2005 @3:25 PM

Article image
What's wrong with Gillian McKeith

For years, 'Dr' Gillian McKeith has used her title to sell TV shows, diet books and herbal sex pills. Now the Advertising Standards Authority has stepped in. Yet the real problem is not what she calls herself, but the mumbo-jumbo she dresses up as scientific fact, says Ben Goldacre.

Ben Goldacre

12, Feb, 2007 @2:29 AM

Australia's scientists serve up diet book that tops bestseller list

· 'Scientifically proven' plan to be published in UK
· Weight-loss programme challenges Atkins claims

Sarah Boseley, health editor

04, Oct, 2005 @11:52 PM

Article image
Mediterranean diet 'cuts strokes and heart attacks in at-risk groups'

Research shows diet can reduce risk for people who smoke, have type 2 diabetes or exhibit other unhealthy characteristics

Denis Campbell, health correspondent

25, Feb, 2013 @8:01 PM

Article image
Why bingeing on health foods won’t boost your immune system
There are only two ways the human body can deal with invading pathogens and infections – and neither involves vitamins or ‘superfoods’

Dara Mohammadi

24, Jan, 2016 @7:30 AM

How 'toxic' diet breeds obesity

Children in the west are principally becoming obese because their diets play havoc with their hormones, according to a new study by scientists.

Alok Jha, science correspondent

11, Aug, 2006 @11:11 PM

Article image
Why almost everything you've been told about unhealthy foods is wrong
Joanna Blythman: Eggs and red meat have both been on the nutritional hit list – but after a major study last week dismissed a link between fats and heart disease, is it time for a complete rethink?

Joanna Blythman

23, Mar, 2014 @12:05 AM

Overweight who diet risk dying earlier, says study
Overweight people who diet to reach a healthier weight are more likely to die young than those who remain fat, according to a study.

Ian Sample, science correspondent

27, Jun, 2005 @4:01 PM

Article image
Should I believe calorie counts?
Luisa Dillner: There may be a difference between a food's listed calorific value, and the amount of calories it actually delivers – but only a small one

Luisa Dillner

01, Sep, 2013 @6:00 PM

Article image
Do I need to eat more fibre?
Luisa Dillner: Few of us consume the amount of dietary fibre recommended by nutritionists and there appear to be plenty of health benefits if we up our intake

Luisa Dillner

04, May, 2014 @5:30 PM