New Study Shows Obesity is Contagious.

According to a new study by Harvard researchers, having more obese friends increases your chance of becoming obese.

Alison Hill, the study’s lead author, said, “We find that having four obese friends doubled people’s chance of becoming obese compared to people with no obese friends.” The study goes on to say that the more obese people you come in contact with, the more likely you are to become obese.

Why? Researchers aren’t sure. Before we shrug off responsibility for our health and point fingers at our friends, it’s important to remember that obesity isn’t like chickenpox—it’s not outwardly contagious. But maybe our eating and exercise habits are. Or maybe people make friends with like-minded individuals that enjoy similar activities, foods, etc.

One thing is clear: Americans are getting even fatter. Obesity is defined as more than 30 pounds overweight. Currently, about 1/3 of America is obese. That number is expected to reach 42% in 40 years, and then level off, according to the researchers.

And if our habits are contagious, it’s yet another reason to lead by example!

What do you make of this new study? Do you find that you and your friends share similar habits?

About Davey Wavey

Davey Wavey is a certified personal trainer and YouTube sensation with more than 250 million video views. For Davey's fitness tips and secrets, sign up for his free monthly newsletter - or download any of his affordable and effective workout programs.


  1. well the people who get obese by hanging around with obesed friends have no self control, they just eat to fit in and care for nothing else they only have a one-track mind.

    where as like you and me Davey we don’t, we have self control WE discipline ourselves.

    BUT if you are like me, i do like to indulge in something naughty every now and again.

    Peace out

    Jay xx

    PS love you Davey

  2. You know, this is interesting. I’ve started hanging around heavier-set people lately, (though one of them has gone from 350 pounds to 225 pounds and I’m so proud of him!) and I’ve noticed that I’ve started to eat unhealthier when I’m with them. They’ll want to go get fast food, and I tag along, and I’m starting to notice a small mountain of candy starting to pile up on my printer (it’s busted and pretty much a huge paperweight at this point haha). Of course, my metabolism is stupid and I still weigh 95 pounds (I’m a 5’1″ female), but I’m starting to realize that I feel unhealthier lately.
    Maybe I’ll take your advice and recommend some better places to get food when I’m with them, or maybe we can have a home-cooked sort of potluck when we hang out for extended periods of time.

    • Also, you’re pretty much delicious. Gay boys are luck you’re on their “team”, so-to-speak. 😉

  3. most of my friends are overweight and i haven’t caught it…yet. oh god!

  4. Well from my point of view, there are two things to be taken into account here.

    1) Obesity is not an illness per se, it is in fact the effect of either an actual disease or of a poor lifestyle. Consequently it cannot be contagious.

    2) We homosapiens are by nature social creature seeking out acceptance and affiliation within a group of peers… within that group a norm will be created by the alpha members aka the cool ones. If the cool ones are either fat or obese, it will technically be acceptable for the smaller ones to gain weight as it will not be considered disgraceful or undesirable…

    So don’t get me wrong, I am not saying that one should avoid hanging out with certain people solely base on the fact that they might be chunkier than they should… however I believe that, like in everything in life, one should balance things off by hanging out with some bigger persons and some smaller ones in order to maintain a balance… as long as they are good Christians LOL joke…

    Anyways that’s my 2 cents 😛

    • Obesity can sometimes be considered an eating disorder, along with anorexia nervosa, bulimia nervosa, and EDNOS. Because these are all partially considered “mental disorders”, it is true that they cannot be caught like a cold. However, like you explained, they can be learned behaviors that need to be disrupted.

      Now something that I think Davey should post about on his fitness blog would be a more recently studied “disorder” known as orthorexia nervosa. In short, orthorexia is where the person is unhealthily obsessed with “pure” foods (no carbs, no fats, raw only, fruitarian, etc) to the extent that it begins to affect their health.

  5. Oh and I forgot… if you don’t want to become fat… come to Canada 😀 we oughta do lots of sport to remain warn 😛 and the lads and ladies are esp. hot in Montreal… just a thought 😉

  6. Once I got over the notion that I didn’t need to clear my plate or eat the same things as other people – I never had this problem.

    That was in first grade.

    • Haha so true… when I was younger I was always told to finish my plate and to think about the poor little Africans with no food… when you think about it, it is SO wrong!

  7. What this study also confirms is that having obese family members also increases your risk of obesity, which we’ve already known, because of genetic predisposition to certain metabolism levels. However, one thing that I noticed is that it is a whole lot harder to lose weight unless your entire circle acknowledges that there is an issue to deal with.

    I guess that’s why I’m frustrated with my dad. He’s slowly losing weight, but is still morbidly obeseand somewhat inactive. I myself need to lose at least 50 lb of fat (BFC-wise, down to about 5-10%) and lower my triglycerides (at age 25, they are already over 500, I think). I’ve started to cut out heavily processed foods and prefer most whole grains (I love potato bread, but I’ve cut back from the half-loaf-a-day I did during college). Yet, it seems like all we have is white rice, because my dad says brown rice “tastes undercooked”. So we have to pander to his wishes and my dietary needs get swept under the rug.

  8. Hey Davy,
    My study shows that it is caused by republican tea baggers in high political office. And I used the same absurd chart they did.
    Where’s my Harvard Grant?

    Sometimes articles like this are used to help and inform.
    Other times they are used to insult, hurt and degrade.
    But thanks for posting it I’m sure it will heat up the discussions here.

    Gotta run, I’m off to McDonalds with a few friends.
    The McRib is back, life is good.

  9. I would love to know what actual disease is affecting my weight, as I am moderately active, on my feet and moving around at work, full time, and I eat a low amount of calories every day. However, I am still struck with this ‘overweight/obesity’ problem.

    Sometimes it’s not the lifestyle, sometimes it’s something else.

  10. Hey Davey.As you know,9 months and 70 pounds ago I was one of the overweights we are talking about.I considered this part of my aging ( 61 ) process.Most obese people do NOT think they are obese, I did not until I calculated my body fat of 35%, now 16%.This along with the onset of type two dib.was my wake up call.Between the weight loss and working out at the gym 6 days a week for the last 8 weeks,I feel like I’m 25 again.I will NEVER go back to the old me.most of the heavy people that know me think I’m taking fitness too extreme.I can not describe the feeling of being in shape for the first time in my life!! Am I crazy??? Love Glenn

  11. I have no friends so no one can influence me LOL.


  1. […] because they’ve adopted similar habits. We know that obesity is contagious; a study by Harvard researchers found that “having four obese friends doubled people’s chance of becoming obese compared to […]