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Comment by aantix | Hacker News Reader

Thoughts on Adenoviruses as being a root cause of obesity?

https://www.geneticlifehacks.com/weight-loss-genetics-obesit...

"Interestingly, animal studies show that the gain in fat mass is not due to eating more or moving less… Animals ate the same amount of chow, but those infected with adenovirus 36 increased fat tissue by 60-80%."

https://pubmed.ncbi.nlm.nih.gov/17135605/

"A 2004 twin study showed that the Ad-36 antibody-positive twins were “significantly heavier and fatter as compared with their antibody-negative counterparts”. This was a groundbreaking study indicating that the Ad-36 virus was likely causing obesity."

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It may be a contributing factor in some cases. The study published in Obesity you link says the adenovirus affects insulin, leptin, and corticosterone. An important note about the third item: "In many species, including amphibians, reptiles, rodents and birds, corticosterone is a main glucocorticoid, involved in regulation of energy, immune reactions, and stress responses. However, in humans, cortisol is the primary glucocorticoid..." [1]. Note that the adenovirus itself wasn't definitively causing obesity, but obesity is caused by the adenovirus' effects on certain hormones.

I highlight this because obesity is increasingly being reestablished as a hormonal problem. See my post and replies for more information about this change: https://news.ycombinator.com/item?id=38942521

[1] https://en.wikipedia.org/wiki/Corticosterone

A lot of viral infections impact cortisol in humans. Infection tends to ramp up cortisol levels, but prolonged or chronic infection can both deplete cortisol (so called adrenal fatigue) and/or make the body more resistant to the effects of cortisol. This is seen in the extreme in the case of HIV. I assume cortisol resistance is analogous to insulin resistance in prediabetics. Apparently chronic stress can have similar effects. And chronic stress may be associated with chronic viral reactivation. [1]

Great comment! Interestingly, depleted cortisol levels from chronic stress may be associated with the development of long covid. [2] I wonder if down the road we will see that people who have had long covid are at increased risk of developing or exacerbating obesity.

[1] - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8470332/

[2] - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9519365/

If this these extremely common viruses were the root cause of obesity, then why does obesity affect different countries so differently?

Viruses all passed around globally so you have to assume all developed countries are getting pretty much the same level of population infection.

Maybe it's because if certain viruses do play a role in obesity, it sounds like an evolved adaptation in humans. Ie, if you're sick, you respond by burning less energy and storing more of it as fat.

Like all evolved adaptations, they don't affect all populations equally. I'm guessing if ad36 contributes to obesity, you must first be genetically predisposed to it happening.

In some cases it may be the root cause, but... is 42% of the US population infected by adenovirus? I think it's unlikely.

In my opinion, it's mostly the excess carbohydrates now compared to what we ate 100 years ago. Occam's razor and all that.

>I think it's unlikely.

"In the reviewed studies, there was a high prevalence of Adv36 in all age groups, which exceeded 64% among adults and 73% among children and adolescents with obesity and/or metabolic disorders. The vast majority of the reviewed studies have shown a statistically significant association between Adv36 and obesity, adiposity, and related alterations, whereas only a few studies presented divergent results."

Adenovirus 36 prevalence and association with human obesity: a systematic review

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7983349/

From the article:

"The obvious reason for obesity is eating too much sugar and refined carbohydrates. But statistically how much does this add to the risk of obesity?

A 2019 meta-analysis of different food intake studies and weight gain showed that consumption of refined grains increased the relative risk of obesity by 5% and the consumption of sugar-sweetened beverages increased the relative risk of obesity by 10%. Eating more legumes, fruit, and fish all tilted the scales in the other direction, reducing the risk of obesity by 5-15%. The study concluded, “The dose-response meta-analytical findings provided very low to low quality of evidence that certain food groups have an impact on different measurements of adiposity risk.”"

Food Groups and Risk of Overweight, Obesity, and Weight Gain: A Systematic Review and Dose-Response Meta-Analysis of Prospective Studies

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6416048/

I was slack and didn't read your links last night, sorry.

From what I can gather, infection with adenovirus-36 basically improves glycemic control... ostensibly a good thing? I couldn't find whether adenovirus-36 was a persistent infection, or whether it only affected patients for a short time, but then they failed to lose weight after the infection had cleared.

This author states that the reason for obesity is eating too much sugar and refined carbohydrates. Why is there a distinction between refined and unrefined carbohydrates? There's no explanation for this, it's treated as given. It's the same chemical makeup, all that changes is the glycemic index. In other words, it's the same poison, it just takes longer to absorb.

The linked study backs this up, but makes no sense from a glycemic load point of view. I notice that vegetables are lumped in one category. Potatoes are not the same as celery. As are fruits, yet blueberries and mangoes have a vastly different sugar content. To add insult to injury, this is a meta-analysis of observational studies, which are notoriously unreliable.

Let me back all this up with a different meta-analysis of interventional trials which treats all carbohydrates the same.

Ketogenic Diet Benefits to Weight Loss, Glycemic Control, and Lipid Profiles in Overweight Patients with Type 2 Diabetes Mellitus: A Meta-Analysis of Randomized Controlled Trails

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9408028/

Thanks for the discussion :)

So why is obesity getting worse recently when Adenoviruses has always existed?

A hypothesis is outlined in the article I linked to above. https://www.geneticlifehacks.com/weight-loss-genetics-obesit...

"If the adenovirus infections are playing a role in our obesity epidemic, this would need to be due to infections rising, starting around the early 1980s, when obesity levels started steadily increasing.

I mentioned above that obesity has doubled since 1980 — and that adenovirus seropositivity had doubled by the mid-2000s (Swedish study).

Here’s the CDC graph again – looking at the green lines (dashed green is women and solid green is men)

One piece of the puzzle as to why this could be happening is the increase in kids in daycare, which has been rising since the 80s. A study looking at overweight kids (9-12) found that Ad-36 increased the risk of obesity by 3-fold and that kids who were in daycare before age 24 months were also at an almost 3-fold risk of obesity.[ref]

Another interesting puzzle piece is that Ad36 was first isolated in 1978 in Germany.[ref] (This may not mean that it first existed in 1978, though, just that it wasn’t well-known before then. Other adenoviruses were identified in the 1930s.)"

Yet obesity rates vary from very high globally. You'd expect a virus to eventually infect everyone.

There is genetic susceptibility, as outlined in the article.

The slimmest country on Earth is probably Viet Nam.

Travelers from all around the world tend to remark that once they arrive to Viet Nam, they start losing weight effortlessly. Upon arrival to the US, the very opposite tends to happen.

Adenovirus/population genetics must be a minor influence compared to cuisine.

As stated in the article:

"Adenovirus infection statistically increases the risk of obesity quite a bit more than eating sugar, refined carbs, not exercising, or eating too much omega-6 fat. However, stacking all of those reasons together likely adds up to quite a bit of weight gain as well. There is no simple answer, but rather is a complex picture of multiple reasons for weight gain."

could also be... the high humidity & heat, smaller portions of food (which are heavily fish and veg based), high rates of smoking, general poverty and simply eating less, etc.

I lost weight in Thailand and later in Australia, and it was mostly because of the heat, sweating a lot, and generally smaller meals. No magic secret here.

Plus the inevitable "Bali belly" that travelers get the first couple days there.

the South is humid and hot but very obese. I think it has to do with metabolism. The rice diet does not metabolize into fat as readily there among the natives.

With something as essential as metabolism it's likely to be a combination of factors. Some might not cause a change when present in isolation but cause a large change when present simultaneously.

As she outlines in the article:

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