Gary Taubes at Low Carb Houston, 2018
A long presentation, but very thought provoking IMO
The global obesity epidemic: Is dietary and animal fat the culprit?
Evidence based on 20 years of investigative journalism.
While I don't claim to be an expert, I'm actually pretty sure that that, the insomnia epidemic, the increasing popularity of depression, and lastly, the increase in auto-immune disorders can all be chalked up to a widespread vitamin D deficiency.
...which in turn is due to the skin cancer scare that originally occurred in the context of widespread tanning bed use and a growing hole in the ozone layer, both of which have actually already been dealt with somewhat. But pharma doesn't want to lose their sunscreen money. And in reality, it's also not the only reason people go outside less.
Don't get me wrong. Sun exposure does increase the likelihood of skin cancer. That's proven. But so does a vitamin D deficiency, and in the latter case it increases the incidence of ALL cancers. That's also proven. A third thing that is proven is that producing vitamin D in your skin is more effective than getting it through supplimentation. One last point... the incidence of skin cancer IS NOT greater near the equator, despite the fact that UV levels are greatly increased at those latitudes.
The only reason I bothered to look into this is because I have severe psoriasis, which can be helped somewhat by sunbathing, so I may have a bit of a bias at this point. There's also a UV treatment device for psoriasis, but I refuse to pay hundreds of dollars for fake sunlight. The real thing is entirely free. And yes, it's that time of year again locally, so it's on my mind.
The links to obesity?
1. Incidence of obesity has been scientifically linked to the amount of time one typically sleeps in a day. The more sleep you get, the less likely you are to be obese. Melatonin regulates sleep... and is also what darkens your skin when you get a tan. I can also tell you from experience that I get a heck of a lot sleepier a lot more often during the season when I actively participate in proverbial sun worship (a.k.a. nude sunbathing, although full nudity isn't an absolute requirement. It just maximizes the effect... that and I often have psoriasis on my butt, and sunlight's effect on that is best with a direct application to the affected area).
2. Sunlight exposure... and even heat, itself, suppresses the appetite. Air conditioning is not a dieter's friend.
That's just off the top of my head. There may be more possible links, but I don't know about them if so.