Tell someone you only bathe once a week, and they might be tempted to give you a wider berth. But how often do we really need to shower or bathe with soap? Every day? Once a week? Never?

A growing number of people are defying the modern cultural norm of daily bathing and simply washing what’s necessary as needed, believing that our skin is better off with less soap and that our natural biome serves as a protective barrier.

“When you wash it, you break it down. You actually break down a wall so you become leaky. And you can increase what comes through the skin,” said Sandy Skotnicki, an assistant professor at the University of Toronto’s Department of Medicine and author of the book “Beyond Soap.”

“I don’t think anybody should go around smelling,” she said in an interview with CTV’s Your Morning on Monday, noting that it is important for teenagers to shower and clean when they reach puberty, for example.

Skotnicki, who is also a consultant dermatologist at Toronto’s St. Michael’s Hospital, said the point is to re-evaluate the “nonsensical” idea that we need to wash our entire body with soap every day.

“You can just rinse and just wash your bits. So we’re not saying don’t shower,” she said. “When you’re just sitting in an office all day, are you dirty? The answer is ‘no’.”

She is not the only one to take that stand. The general consensus from dermatologists on multiple health and lifestyle websites is that we shower too often.

Katherine Ashenburg, the author of “The Dirt on Clean: An Unsanitized History,” noted in a 2010 New York Times article that, “we have never needed to wash less, and we have never done it more.”

Modern ideas of equating cleanliness with daily washing are rooted in marketing, and grew as indoor plumbing became more common in the 20th century. 

Today, this is evidenced by commercials and ads for soaps, shampoos, antiperspirants and deodorants, and other cleaning products. According to Grand View Research, the market size for global soap and detergent (which also includes household and commercial laundry detergents) in 2016 was estimated at US$97.26 billion.

And when the topic of hygiene enters the public sphere, the debate can be intense. Earlier this year, a discussion on leg washing erupted on Twitter after a user posted a poll asking the public whether they washed their legs when they showered. Many users were shocked by the number of people who responded “no”. A few days later, the conversation heated up again after Taylor Swift told Ellen DeGeneres that “shaving cream is basically soap.”

But as late as the 1950s, washing once a week was the norm. And in the U.K., soap was also rationed between February 1942 and September 1950, according to the Imperial War Museums and the BBC.

Still, the larger issue, Skotnicki said, is looking at whether we have changed our skin’s microbiome through all the cleansing products we have been using over the last 70 years. 

The more ingredients in a cleanser, the more likely something will strip your skin of essential natural oils, dermatologists say. Frequent washing can result in dry and itchy skin because the practice removes sebum, a fine layer of oil that protects and keeps our skin moisturized.

That is what motivates David Whitlock, founder of AOBiome and a former chemical engineer who has not bathed in 15 years, according to a recent article in The Guardian. If a specific part of his body is dirty, he will wash that part, but not with soap. Whitlock’s practice is meant to encourage good microbes to live in “symbiotic harmony”. The result? He does not have body odour, and he gets “low-maintenance, balanced skin”.

But what about kids? Unless they are dirty, a rinse with water two to three times a week for healthy children is perfectly fine, Skotnicki said. “You don’t have to every night, it’s not necessary!”