Prevalence of obesity is rapidly increasing even in the not so developed countries. We know that at least 60% of the people in UK and USA or either overweight or obese.So, is obesity contagious ? Can you get infected by an obese person?


The spread of obesity

Investigating obesity and its causes has been a challenge for the last few decades. This has been especially important given that the prevalence of obesity is increasing rapidly. We seem to know what the reasons for our weight gain is. However, we all like to believe that this is not entirely down to us and our individual choices and actions. And this is true to some extent. It has been brought to attention that the genes we inherit are partly responsible for our Body Mass Index(BMI).

Like many other health conditions, obesity is the result of both, environment and genetics. Studies have confirmed that several genes may contribute to weight gain although the genetic factors comprise only a small part of the overall risk.

If that’s the case, is it true that obesity could be contagious?


Contagion of obesity

Social contagion of obesity has been examined in a few studies and it seems that the ‘obesity virus’ spreads via our social networks, mainly amongst friends.

It is often the case that within groups of friends if one of them gains weight, others tend to follow. You can probably relate to this when observing you and your friends and how alike you tend to be. We have all probably also noticed that groups of friends tend to be of the similar physique. Is it that we chose as friends people who are similar to us or the other way around? As the old saying goes, ‘who keeps company with wolves, will learn to howl’.

According to studies, our chance of becoming obese increases by an astonishing 57% when our friend becomes obese. Interestingly, there was no such effect when a neighbour or a family member became obese. We can then assume that it’s not necessarily solely the environment that affects our susceptibility to gaining weight. Some studies suggest that proximity does not matter. This suggests that obesity may have more to do with a shift in social norms rather than behaviours.


Social contagion explained

But do our friends really affect our perception of body size to this extent? It seems that we are more acceptant of obesity if it happens to our friends. This, in turn, relaxes our views and we tend to get familiar with a certain type of appearance. We no longer perceive such appearance as ‘out of the norm’. Studies explain that living in a certain community can affect what is socially acceptable when it comes to eating habits, physical activity and body size. We all know that our environment and social circles affect our behaviours, beliefs and values. This seems to also be true for eating habits and body size.

This may be one of the reasons for accepting obesity as the norm in several states in America. Despite more people becoming morbidly obese, the number of people seeking help sadly is not increasing. People have started to accept being obese is okay.


What should we do?

Let’s all keep in mind that when being in social situations, it is worth paying attention to our dietary choices rather than trying to fit in. Trying to be part of the crowd may not always be good. At times we also need to be a bit selfish and do what is best for ourselves. And let’s be honest, our friends would probably benefit from us being assertive but supportive. It is also a good idea to, once in a while, evaluate our views and assess whether what we perceive is an objective view or whether it is affected by our environment and by what we are familiar with.

Click to read a related blog on gut bacteria:


Poo pill for weight Loss

It has been seen that when an obese person gets to live with a slim partner, the slim partner gradually gains weight in most cases. This may be due to change in life style. However it may also be due to change in intestinal microbiomes. Intestinal microbiomes or gut bacteria play an important rule in digestion, hunger and fullness.

Faecal microbiota transplantation (FMT) has been used to modify gut microbiota as it has been associated with improved clinical outcomes in recurrent Clostridioides difficile infection. C-Diff infection leads to profuse diarrhoea and is usually after having antibiotics. The antibiotics destroy the intestinal bacteria.

However, the potential usage of FMT in weight loss is still not widely used in human being. Please click on these Links to learn more about FMT and

Research is still being done to see if faecal microbiota, not faeces is taken from an healthy and slim individual and transplanted to an obese person would lead to weight loss. This has been tested in mice and shown to be successful.

In conclusion, yes tendency to gain weight can be infectious in some situations.


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