[uoaei]

I've reduced my skin and scalp's dependence on soap and shampoo, and now a vigorous rinse in a hot shower gets me 95% clean. I do use a mild (minimal glycerin content) soap on sensitive parts. Whatever it is that accumulates on my body over time has become less oil-based (more water-based) and after some time in hot water begins mixing (emulsifying?) so that I become clean.

This helps you to live with a healthy skin microbiome that is effective at maintaining itself. I can easily skip a shower for a day and be fine, because the buggies living on my skin help manage the population of bacteria and yeasts that ultimately contribute to smells, pleasant or otherwise.

However the transition from Western-style harmful hygiene practices (harsh soaps, extreme obsession) back to a more normal baseline can take a while, and requires being a little gross as your body re-learns to manage itself without such drastic outside measures as strong surfactants.

tl;dr your skin and scalp easily develop an unhealthy dependence on external soaps, resulting in a chronic inability to manage skin microbe populations, which means you're covered in uncontrolled colonies of stinky microbes until your next shower. Let your body handle it and it will manage those populations itself.

[Beaver117]

Are there any actual studies on no-soap and no-shampoo? I've only ever heard anecdotes.

[mixmastamyk]

Not the main problem. It is a stinky bacteria infection in the armpits. Coincidentally uncommon in Japan. No amount of washing will fully get rid of them because they are beneath the skin in the sweat glands.

[hutzlibu]

"It is a stinky bacteria infection in the armpits. "

If it is a infection, then something is very wrong.

Otherwise you can and should clean them with care, especially when you cannot shower.

[mixmastamyk]

Not at all, hundreds of millions have it. Normal but stinky.

Most folks don't realize, but sweat itself has substantial odor.

[hutzlibu]

A infection in the armpit, is not something normal. Odor and sweat and lots of bacteria is, yes, but that is not an infection. It can become an infection.

[mixmastamyk]

See def #3: https://www.dictionary.com/browse/infect

[mixmastamyk]

Hah, has no substantial odor.

[Alcor]

To clear this up a bit, you are most likely referring to a mutation in the ABCC11 gene often associated with and common in east asian demographics. The gene mutation causes earwax to be dry instead of sticky and seems to inhibit production of certain proteins in the sweat glands:

"To learn the reason behind why this gene affects body odor, the origin of body odor itself will also have to be examined. To learn why, it must be noted that sweat itself is odorless. Body odor comes from the apocrine glands in areas such as the armpits and genital regions, and is caused by bacteria feeding on proteins produced by the apocrine sweat glands. However, with the gene mutation in ABCC11 gene, these proteins are not made, causing sweat to remain odorless."