Why we eat less around our friends

00:04, Aug 09 2012
Social eating
HURRAH: Science can back the theory that we do in fact eat less, or more, when around certain social circles.

Friends don't let friends eat cookies. That's the finding of US researchers who have been looking at how what your friends choose to eat can influence you.

They got groups of three friends together, instructing two of them to restrict what they ate while the group completed a task. They also had control groups who were allowed to eat whatever they wanted.

Not only did they find that the third friend eat less when their friends ate less, but the friend continued to restrict their intake of the fresh-baked bite sized chocolate chip cookies after the others had left the room.

I learned a number of things from this study: first and foremost that reading about chocolate chip cookies really, really makes me want to eat a chocolate chip cookie.

But it also got me thinking about the ways in which our friends can influence our weight (and health).

"These findings both contribute to the current understanding of social norms and suggest a possible mechanism for how obesity or disordered eating more generally may ''spread'' through social networks," the authors wrote about their study in the journal Appetite.

"However, social norms may also support healthy eating behaviours, thus representing a particularly salient and modifiable environmental factor that may contribute to the long-term maintenance of weight."

For a while now scientists have known that obesity tends to cluster in groups, with a landmark study from 2007 finding that a person has a 57 per cent increased chance of becoming obese if he or she had a friend who became obese in a given interval.

If one adult sibling became obese, the chance that the other would as well increased by 40 per cent, and if one spouse became obese, the likelihood that the other would increased by 37 per cent.

But what is less clear is why. Is it because among friendship groups we tend to share attitudes about food and exercise, or even body image? Or is it just the little decisions we make every day about what and how much to eat or how much exercise we should do are subtly influenced by the decisions our friends make?

Recent research even indicates that the weight of your friends when you are a teenager can go on to influence your weight many years later. (In all these studies they attempt to account for other factors that influence weight such as socioeconomic status).

The people you spend time with can influence you in thousands of different ways, something I often notice in my own behaviours.

I still wonder if my co-worker losing 20 kilograms was the thing that tipped me into my own weight loss (reading her column certainly influenced the way I went about it).

And I know for sure when I go to the gym in the morning and see someone working really hard it can inspire me to do the same.

I have also, I'm sad to admit, experienced the nasty feeling of guilt for tucking in to a big meal while a friend orders a salad.

Of course, it is likely there are no hard-and-fast rules about how and why your friends influence your food intake. Even in this study there was a wide variety in the ways people ate.

In fact, the researchers ended up having to exclude three groups from their final analysis: one because the people who were told not to eat went ahead and ate anyway, another because the two friends ate SO MUCH food that there was none left for the last person and the last because the third friend at so much more than everyone else in the study that they would have messed up the results.

Clearly there was a lot more going on there than just the influence of two friends over another.

So with that - sorry friends - I'm off to get that cookie.

- Daily Life