As the owner of an online retailer of lingerie and swimwear, it's not surprising Katherine Hancock, 29, likes to stay in shape. She does this by limiting carbs, eating plenty of fresh fruit and vegetables and going to the gym five days a week.
But when she's out with her old uni friends, her resolve crumbles. She finds herself ordering things she wouldn't normally eat, from creamy pastas to wine, cocktails and rich desserts. "I can't watch my friends eat it and not have any," she says.
"When we get together we seem to give each other a 'leave pass' to eat the things we've been desperately trying to avoid," she explains. She says she would feel "rude" not joining in, but also feels "food envy" when watching her friends eat. "I don't want to be the only one at the table with a celery stick when they have delicious plates of pasta ... It just seems easier to indulge."
Now new research shows we're not only more likely to indulge when watching others do so, but simply hearing about other people's food choices has the same effect. Published in March in the Journal of the Academy of Nutrition and Dietetics, the meta-analysis reviewed 15 studies, and the researchers found that when participants were told others were eating high-kilojoule or larger-sized meals, they were more likely to do so, too.
Conversely, participants consumed less kilojoules when told others were eating low-kilojoule meals. Which led Eric Robinson, lead investigator of the study, to conclude: "Eating behaviours can be transmitted socially."
Sydney-based psychologist Victoria Kasunic says this occurs because we're programmed to match each other. Not just when it comes to eating, but also our gestures, postures and language: "We tend to mimic without even realising it." She says this mimicking behaviour helps us connect with others and gives a sense of belonging.
While we're all "social creatures" who like to belong, Kasunic says women are "more socialised to fit in". Which means women are even more inclined to act like the person they're spending time with. "So when we're with someone and they're saying, 'Let's have dessert,' we're very cued in socially to go, 'Oh, okay then.' It's much harder for us to say no."
Your weight can also be affected by your friends, according to a study published in the New England Journal of Medicine in 2007. The study analysed more than 12,000 people over a period of 32 years and found a person's chance of becoming obese increased by a massive 57 per cent if one of their friends became obese.
Kasunic says this occurs because we judge ourselves against our peer group. So if you're surrounded by overweight friends, that's then considered the norm. "[People] don't want to stand out from their friends or be seen as different," Kasunic notes. Furthermore, if your friends are overweight, you'll also be less motivated to lose weight, as doing so can lead you to "feeling on the outer".
The good news, however, is that while your friends' size can influence you negatively, it can have a positive effect. "It also works in reverse," notes Kasunic. So if your friends are starting to slim down, you're more likely to want to join them. Plus, she says, exercising with a friend or choosing to eat healthier food together makes you more likely to stay on track.
So if you embrace healthier food choices, one day your friends – and their waistlines – may thank you for it.
Eating with friends: smart tips
• When eating out, choose a restaurant you know has healthy choices.
• Look up the menu online before you leave and decide what you'll order before arriving.
• Have a healthy snack before eating out so you're not ravenous – and vulnerable to poor food choices when you arrive.
• Order your food first, so you don't get tempted to change your mind when you hear what others are having.
• Invite friends over for meals so you're in control of the food on offer.
Source: nutritionist Emma Sgourakis, The Nutrition Coach, Melbourne.