Peptides are basically protein precursors. A bunch of workout gym bro types have been taking concentrated supplemented peptides for "building muscle" and other purported health benefits, which idk if it really helps or not.
But they are a grey market "supplement" that is not regulated and often imported from overseas pharmacies, pushed heavily by tiktok/Instagram influencers because there's money to be made in shipping them.

As other people mentioned peptides are technically protein precursors. Recently there was the huge increase in the usage of Ozempic, which is a brand name of a peptide called Semaglutide. Other peptides supposedly have different effects on your body. But it's a relatively new class of medication and for most we have no real data of any positive or negative effects.

Since one peptide was proven to work, suddenly a lot of snake oil salespeople jumped on the bandwagon trying to sell them as some kind of miracle supplements. Take them at your own risk. Might give you muscles. Or you might grow horns or something. Who knows, none of it is tested properly.

Is it a new social media trend or something?

Yup. TLDR its basically a step below steroids. While I can't really speak to their safety etc, I do know that there are no legal OTC peptides in Canada. However that could simply be because Health Canada has very high standards and a lot of hoops to jump through, making our 40 million people market not worth it.

additionally, WIRED’s stance is they’re likely a scam

There are a lot of different peptides. While there are some that are used by bodybuilders, there are others like collagen, which people take to improve their hair, nails, and skin. Collagen supplements are available anywhere in the US, some of the others are only available from "certain sources" (as noted above).

Good Work summarized it better than I ever could: https://youtu.be/W0ltbBby9FU

As others have noted, they are molecules that make up proteins. So not one thing at all, just a description of the type of molecule.

Most are being rushed to market in front of the science, and some are unavailable through legit channels so there's no guarantee what you are shooting up.

But the ones that are studied and work are really cool. GLP drugs have helped so many people, and the research keeps getting better and better on them. CBL-514 looks like a miracle - something that can dissolve abdominal fat preferentially, sparing all other tissues. I would love that - if I lose weight it leaves first from my legs & ass and boobs, stomach does not budge until I am a ruler shape. Sermorelin is pretty well studied too - growth hormone releasing hormone. Copper peptide speeds wound healing.

So I think they will become a drug category and get regulated, especially as people discover new ones and patent them. Right now it's sort of the wild west, people are likely harming themselves.

RFK jr's new grift