Social networks can affect weight, happiness

Anthony Komaroff, MD

Editor in Chief, Harvard Health Letter

The people you live with, work with, talk to, email, chatter with on Twitter and Facebook—your social network—can be good medicine, or bad.

The intriguing new science of social networks is demonstrating how personal interconnections can affect our health. Ideas and habits that influence health for better or for worse can spread through social networks in much the same way that germs spread through communities. In social networks, though, transmission can happen even though the people may be hundreds of miles apart.

An article in the December issue of the Harvard Men’s Health Watch explores how social networks can affect weight and mood.

Spreading weight

A study of people taking part in the landmark Framingham Heart Study found that if one sibling became obese during the study, the chance that another sibling would become obese increased by 40%. You could write that off to genetics. The same thing happened if a spouse became obese. Again, no surprise, since spouses share meals and may have similar exercise habits. But if study participants had a friend who became obese, the chance the study participant would become obese rose by 57%. Sure, friends share some meals, but nothing like most meals.

Although scientists don’t fully understand how obesity spreads, they suspect that a social network influences what its members perceive as normal and acceptable. If people see their friends becoming heavier and heavier over time, they may accept weight gain as natural, even inevitable. Instead of exercising more or eating less when their weight begins to creep up, they may simply go with the flow and join the crowd.

Incidentally, there is evidence that the influence of social networks can also work in the other direction, and help people maintain a healthy weight.

Spreading happiness

A different study of the Framingham participants showed that happiness can also spread across social networks.

In the study, happiness spread more readily between members of the same sex than between people of the opposite sex. It also seemed to reach across at least three degrees of separation, spreading, for example, from a friend to the friend of a friend and then to the friend of that friend. But the impact diminished with each degree of separation.

Harnessing the power

The more we know about how healthful habits, positive attitudes, and wise lifestyle choices spread through communities, the more it will help experts use natural social networks to improve public health. As the Harvard Men’s Health Watch article concludes, “This new area of research is worthy of further study, so for now, call it a network in progress.”

You can read the complete article on the Harvard Health website.

Related Information: Harvard Men’s Health Watch


  1. Anonymous

    Thank you for sharing this insightful article. I think social network do some changes but not affects some of it.I’m glad reading in this nice article. Will be sure to share this.

  2. baby cots

    This is so true. since graduated last 2 years and spent most of my review for licensure exam is at home. and on my spare time i will just browse with social networks and could stay till 5-8 hours and more. What Ive observed is the lack of sleep and weight gain..From size 8 to size 14 now.. 🙁

  3. anonymous

    I guess it depends on how you use social networks and how much you use them. Like anything else, there can be such a thing as too much of a good thing. Maybe the people who are becoming obese from social networks are on them too much and not doing things they use to such as: walking, exercize, and moving around.

  4. DiwanEgypt

    Social media sometimes causes happiness
    And happiness sometimes causes weight loss 😀

  5. Adrian

    It is amazing how we can influence others the way we do. And it is important that we take advantage of the time and moment. The good we share will help all of us one way or another.

  6. Amit

    Good information for health related issue.

  7. Angelo Bonavera

    I disagree with your post Anthony Komaroff, M.D,

    People who conform to others instead of thinking for themselves is a big problem in modern society. We live in a democracy.. our government depends on individual thought to better itself.

    In fact why are you even presenting a new idea to people if you believe they’re conformists.. if it’s true they wouldn’t listen.

    If people indulge in the irrational idea of ‘normalcy’ or develop habits instead of thinking, it’s a sign they have a strong ego-defense-mechanism. In other words they have a compulsive disposition that should be addressed.

    For example, if someone convenes themselves that eating beef is normal just because they want to fit in.. or just because they like the taste.. this is called a ‘rationalization’. Indulging in the ego-defense mechanism like this had no beneficial place in modern day societies and can lead to much worse things then living unhealthy life styles.

    I would also like to challenge your correlation between social networking and the spreading of habits. Most people are obese so if what you’re saying is true that habits spread more if there’s more social interaction, then the country that social networks the most should have the most obese population.


  8. Praneeth Gangaboina

    Yes i agree with Mr : Michael. Social networking can be used flawlessly in opining the present Govt and its Strategies which decide the future of the nation. It can be used as a lethal weapon to flush out the corrupt Govt and help bringing up the bill in which the govt and people’s representatives are considered for applying the same rules and acts which are applied for the common man. I want India to be the one with all the perfect rules and Anti-corrupt Nation in the World.

  9. Michael

    There is another side to health and social networking, one which intends to connect people suffering from illness and disease, globally, allowing them to discuss there condition and socialize with others who can relate, something that is often missing.

    Its been happening for years in forums, but social networking takes it to the next level.


    • simone

      That is a very good point. I wonder how many people know that this support exists.
      There is a group called the National Empowerment Center from the Boston area where people with mental illness can support each other. I bieleve similar groups exist in other states as well.

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