Is nutrition information worse than useless?

Pondering food labels
Image courtesy of http://www.flickr.com/photos/cuccia

In my previous post, I shared the results of a study that seemed to show that food labels aren’t especially helpful if you’re trying to loose weight. Since then, I’ve been reading up some more on the effects of food labelling some more, and I’m starting to wonder whether a reliance on nutrition information may be actively harmful to weight loss, not just unhelpful.

Of course, there’s a damn good chance you already know this from your own bitter experiences.  If you’re like me, you’ve probably read the side of a carton of ice cream just a bit too late and spent the rest of the day thinking you’ve screwed up your diet. So accurate nutritional information can certainly have its downside. But surely, overall, knowing the calories and grammes of fat in what you’re eating is helpful? It just must be.

That’s certainly the conventional wisdom. ‘Use of food nutrition labels is associated with lower fat intake’.  So proclaims the title of a paper in the Journal of the American Dietetic Association in 1999.  The authors spoke to 1,450 people in Washington state and asked them to answer some questions about their use of nutrition labels and what sorts of foods they regularly ate.  People who said they ate less fat, also said they took notice of labels more.  The authors conclude that nutrition labels are helpful.

Now, I have a completely crazy idea. I believe that trousers have a fertilising effect on shoes, such that the more trouser material you have, the bigger your shoes grow. In fact, I’ve tested this out by measuring a lot of shoes. And a lot of trousers. And if a person has big trousers, they also are more likely to have big shoes. No? Why not? Yes, of course, I should put some big trousers on a person who doesn’t normally wear big sizes and see if their shoes grow. That would be a better test. And that’s precisely why I don’t buy the results of this study. We know that people are told by government propaganda and by most dieticians that fat in food is bad, and that certain types of fat should especially be avoided.  Is it really surprising that someone who believes that dietary fat is bad would look at labels to see what foods have got lots of fat in? Findings from studies like this do not show that labels encourage healthy eating.  They show that people who are already making considerable efforts to eat healthily, read labels… because they’ve been told to by the experts. And whilst we’re about it, the authors conclude that label use and fat intake are only associated at about 6% (of variance) anyway, so even with the author’s generous interpretation, paying attention to food labels to watch your fat intake doesn’t seem to have much effect.

Some scientists have done more telling experiments of course. Here are a couple of examples from each end of the social spectrum….

Students in Berkshire

In 1995, Jacqueline Aron, Rhian Evans and David Mela, from The Institute of Food Research published the results of a beautifully simple study in Nutrition Research.  For the experiment, they recruited 65 students on campus, who typically ate lunch at a given cafeteria.  The students agreed to continue eating lunch in the same cafeteria.  They also recruited 25 students who typically ate at a comparable cafeteria elsewhere on campus, and who would agree to carry on going to their favoured eating and watering hole.

In the experimental cafeteria, they then agreed with the catering manager to place laminated 8cm square cards, bearing accurate nutrition information, near each of the food choices.  These labels had information on them about calories and fat.  By surreptitiously recording what foods the students chose, they were able to show that the introduction of labels was associated with a slight increase in consumption of unhealthy foods. Information about the food had made the diners’ choices less healthy The effect was most marked amongst so-called ‘unrestrained’ eaters.

These findings are hugely counter-intuitive of course.  We expect that if someone tells us some food is less healthy, then surely, we’ll eat less of it.  But these kinds of findings seem to come up each time a rigorous experimental approach is taken to the question of the usefulness of nutrition information.

Poorer Neighbourhoods in New York

In 2008, New York introduced a mandate that all chain food sellers, including sit-down and fast food restaurants, must publish information on the calories contained in each menu item. Brian Elbel and colleagues, at New York University, tried to track the effects of the changing local laws by stopping people as they were about to go into McDonald’s, Wendy’s, Burger King, or KFC, in the poorer neighbourhoods of the city, and offering them $2 if they brought their receipt back to the researchers on their way out. They did this just before and just after the introduction of calorie labelling in these restaurants and found no change in the number or pattern of calories consumed. The respondents did however, claim that the labelling made them think about their food choices, and a large proportion said they’d chosen to eat fewer calories because of the labelling. I find this even more worrying. Eating the same number of calories whilst thinking you’re eating fewer, seems pretty dangerous to me.

I’ve come across studies like this for about ten years now, in my day job as a psychologist, but I’ve never really stopped to think about the effects these things have on my diet. Despite the evidence base, we’re still drowned in diet-related information.  All of this information means our choices are based not on what we want, most of the time.  This is especially true of those of us who are unhappy with our current bodyweight, because we’re more likely to be trying to stick to a diet plan.  We eat what we should eat according to the information handed to us by governments, health departments, and, most of all, advertisers.

The take-home message

  • ‘Only 3 grams of fat per serving’ is meaningless if your own idea of a serving is three times the tiny suggested serving.
  • Reading the label or counting your calories might mean you think you’re eating more healthily than you are.
  • At best, relying on nutrition labelling and calorie-counting is likely to be a hit-and-miss approach to weight loss.

 

 

Aron et al. Paradoxical effect of a nutrition labelling scheme in a student cafeteria. Nutrition Research (1995) vol. 15 (9) pp. 1251-1261

Elbel, B., Kersh, R., Brescoll, V. L., & Dixon, L. B. (2009). Calorie Labeling And Food Choices: A First Look At The Effects On Low-Income People In New York City. Health Affairs, 28(6), w1110–w1121.

Neuhouser et al. Use of food nutrition labels is associated with lower fat intake. Journal of the American Dietetic Association (1999) vol. 99 (1) pp. 45-53