How your friends affect your health

Choose your friends wisely – for your health.

How your friends affect your health

Tina Leggio/Flickr, CC BY-SA Carol Maher, University of South Australia and Tim Olds, University of South Australia

Think about your five closest friends. What do they care about? Do they love the gym? Long walks on the beach? Maybe they smoke, or are overweight. You should choose your friends wisely, because they can have a big influence on your health.

Growing evidence suggests disease spreads through social networks. According to a US study which followed 12,000 people for 32 years, if you have a close friend who becomes obese, your chances of becoming obese increase by 171 per cent. And your risk of attempting suicide is four times higher if you have a friend who has tried to kill themselves.

So, if social networks can make you sick, can they also make you healthier? It seems they can, but in one of life’s annoying asymmetries, the health effect doesn’t seem to be as strong as the illness effect.

Recent studies have shown that quitting smoking spreads through social networks. If your significant other quits you have a 67 per cent decreased chance of smoking.

And research confirms what we have always suspected – happiness is contagious. Your chances of becoming happier increase if you are surrounded by happy people.

The strength of the contagion depends on how close you live, and your relationship with the happy person. The strongest effect occurs if you have a happy friend who lives within 1.6km of you (25 per cent increased chance of becoming happy).

Happy siblings or spouses can also help, but less so, increasing your chances of becoming happy by 14 per cent and eight per cent respectively. Happy co-workers have no effect at all, so it’s okay to be grumpy at work.

Is health really contagious?
But couldn’t all this be due to like people attracting like? Scientists have tested this. It seems the effect really is due to the behaviours spreading over time, from key central “nodes” to their social connections. The spread can be seen up to three degrees of separation, so you can actually influence the friends of your friends’ friends.

The “direction” of the connection is also important. The study examining obesity’s spread through social networks found that if you consider someone your friend and they became obese, your chances of becoming obese increase modestly (57 per cent increased risk).

Yet if they consider you a friend but the feeling isn’t mutual, your risk of obesity is unaffected. Worst of all, if you consider each other as friends and your friend becomes obese, your chances of becoming obese nearly trebles (171 per cent increased risk). But we’re not suggesting that you unfriend your overweight friends as a preventative measure.

As this contagion effect of health has become recognised, researchers have tried to exploit it to improve health. In a 2015 study, public health scientists delivered a multivitamin supplement program in rural villages in Honduras.

The program was spread using word of mouth, starting with five per cent of village residents. In some villages they randomly selected the initial targets, and in other villages they randomly selected individuals, asked them to name a friend, and then these nominated friends became the initial targets.

Uptake of the multivitamins was significantly higher in the villages where the initial targets were the nominated friends. This exploits the “friendship paradox”, that on average, your friends have more friends than you do.

What about online social networks?
Online social networks also present a ripe opportunity to deliver health programs. Our recent review identified burgeoning scientific interest in this idea, with promising results. Our study of a gamified Facebook app which helps users team up with online friends to compete in a 50-day physical activity challenge led to a two-hour-per-week increase in physical activity.

Other programs have targeted a wide range of health behaviours, including weight loss, exercise, quitting smoking and sexual practices.

Using online social networks to improve your health isn’t for everyone. Sharing health information online can be confronting. But, on the upside, social networks provide public accountability, opportunities for social support, and friendly rivalry – all powerful motivational tools.

If you are interested in trying an online social networking exercise intervention, join our new study and recommend a friend.The Conversation

Carol Maher, National Heart Foundation Senior Research Fellow in Physical Activity, Sedentary Behaviour and Sleep, University of South Australia and Tim Olds, Professor of Health Sciences, University of South Australia

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Have you noticed how your friends can affect your health? And you mood? Have you shed some ‘friends’ as a result?

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    30th Jul 2019
    I would think that one's family is an even bigger influence on one's health.
    30th Jul 2019
    What a load of total bullshit.
    30th Jul 2019
    Where does this rubbish come from? One of my closest friends of over 50 years is a smoker. I haven’t taken up smoking neither am I going to drop her. Frienship is a precious thing
    30th Jul 2019
    AsI always say: You can pick you nose, you can pick your friends.

    But you can't eat your friends!
    30th Jul 2019
    This a load of nonsense. I had a friend who smoked. I never smoked.
    30th Jul 2019
    This a load of nonsense. I had a friend who smoked. I never smoked.
    30th Jul 2019
    I owe it to to a couple of good friends who kept my life stable at a time when i went feral and lost my belief in everything.
    30th Jul 2019
    I am safer and happier with a friend who is overweight than one woman I considered a friend who turned out to be a narcissist. She damaged my mental health with her vicious bullying and attack when I fell in that she was expecting to control me and I said no. Narcissists are charismatic at first so you think they are nice people. They are to be avoided at all costs!!
    30th Jul 2019
    So that is why I don't have many friends, I am too healthy for them, seriously though I always just made my own choices when it comes to my health and always looked after myself no matter what my friends were doing to theirs. I guess some people are just easily influenced. Friends do drop off at times though when you make changes in your life.

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