It has long been known that obesity is not always and not only due to overeating. But did you know that it is possible to «catch» obesity? Let’s see what the research says.
Years of epidemics have reminded us what a contagion is. But it’s not unreasonable to remember that even diseases that are not contagious can also be contracted. For example, obesity.
A few years ago, geneticists wrote about the fact that obesity is at least partly an infectious disease. Because the gut microbiome plays a role in it. That doesn’t mean you can get an infection from an obese person if you drink out of a cup with them or if they sneeze on you. But in an experiment, you can make a mouse fat if you put a microbiome from an already fat mouse or human into his gut.
A microbiome is a microorganism or a community of microorganisms that inhabit a specific environment. In this case, we are talking about the gut microbiome.
Most likely, if a person manages to get and select obesity-related microbes in his gut in the course of his life, they will drive him to that obesity. This is reflected in many studies.
Is obesity contagious?
But it turns out that obesity is even more contagious by a more obvious mechanism. Social. We get infected and our environment gets infected if someone close to you has become overweight, your chance of following their example increases by 57%. If your brother or sister suddenly became obese, your chance of becoming obese also increases by 40% (according to the study «The Spread of Obesity in a Large Social Network over 32 Years»). And it’s not about genetics, it’s about acquired traits.
And if it happened to your spouse, your chances are 37% higher. Interestingly, the geographic connections between friends and relatives are weaker than the degree of your connection. It doesn’t matter as much how far your friends live from you, they will «catch on» to you even if you are communicating by zoom. Friends of the same sex are more likely to «infect» each other than the opposite sex. The higher your income, the more beautiful your waistline, which is associated with better education, and nutritional awareness (data from the study «The Spread of Obesity in a Large Social Network over 32 Years»).
The more friends you have with unhealthy habits with whom you socialize while trying to lose weight — the worse for weight loss (data from the study «Social networks and social norms are associated with obesity treatment outcomes»). Lots of social connections can have both bad and good effects. Apparently it depends on who those connections are with.
Obesity and homophilia
The big picture looks like this: your environment affects your weight just as much as genetics, hormones, and the prescriptions you’re used to. The denser our ties with fat people, the longer and more frequent they are, the stronger they are. In couples, there is an effect on homophilia. In simple terms, homophilia is when the habits and characteristics of one partner are eventually adopted by the other. And who in the couple will have the greater influence, nature alone knows. From here comes an alternative and effective, and has long been noted by scientists approach to weight loss: watch not only the plate, but also the attitude to healthy eating in themselves and their loved ones.
But geneticists, they add, have not cancelled assortativity in couples. And we might as well assume that we pre-select as friends and partners someone with whom it will be fun to slam the fridge door at midnight. It is just a habit that someone acquired earlier, someone later, and only omniscient genes notice the rudiments of the properties, close to us, in others from afar and in advance. And they push us to go out with this very partner. But all this will have to be proved…