From Memetics to Metabolomics

Obesity, heart disease, and diabetes may be communicable
Jan 2020, phys.org

I learned in health school that we are living in the fourth epoch of public health, the one where chronic disease (4th) is more of a problem than infectious disease (3rd). Public health interventions are not about killing germs, but about improving your lifestyle (in addition to arming yourself with knowledge of adverse genetic predispositions and environmental exposures).

So when that idea came out that obesity is a meme that infects via your friend-vector-network, it already made sense. Mind viruses, it's the 21st century.

This sums up the mechanics:
“You change your idea of what is an acceptable body type by looking at the people around you,” Dr. Christakis said..
-New York Times

But now we're swinging back in the other direction, back to the days of infectious immunological threats. Threats that come from the microbiomes of our friends and neighbors and countryfolk.

This rewrites and reverses the current underpinning theory of public health, which is that your behavior is a major cause of your own health outcomes (even if that behavior is resulting from memetic infection). This new idea is that you're being infected all right, but by the same old bacteria, fungi, viruses that caused the previous "Infectious Era" of public health.

The consistent part of all this is the social network, or network science in general, and that our hands aren't on the wheel.

Notes:
Are noncommunicable diseases communicable?
B. B Finlay et al. Science (2020). DOI: 10.1126/science.aaz3834

The spread of obesity in a large social network over 32 years.
Christakis NA, Fowler JH. N Engl J Med. 2007 Jul 26;357(4):370-9. Epub 2007 Jul 25.

This is the study about obesity being contagious; it was a social network analysis based on the Framingham Heart study, which is known as a good dataset in health science.