Instagram's public policy manager Emma Collins said in a statement on Wednesday that the changes were aimed at dealing with the growing industry of influencer marketing on the platform.
"We want Instagram to be a positive place for everyone that uses it and this policy is part of our ongoing work to reduce the pressure that people can sometimes feel as a result of social media," Collins said.
The restrictions will only apply to users that Instagram knows are younger than 18 - however, the app does not ask users for their date of birth when they sign up. Instead, users signing up are simply asked to tick a box declaring themselves over 18 or not. If they sign up using a Facebook account, their age information is pulled from their Facebook profile - which is also not usually verified.
The company plans to introduce new tools in the coming weeks that will allow users to report a post within the app if they believe it violates the new policy.
The Good Place actress Jameela Jamil said the move was a "huge win" in the fight against the diet and detox industry.
The actress, who had taken major celebrities to task over their endorsement of "detox" teas, lollipops, and supplements in the “I Weight” movement, has publicly criticised influencers such as the Kardashians and singer Cardi B.
"We are changing the world together. After a bunch of shouting, screaming, and petitioning... we have managed to get the attention of the people at the top, and they have heard us and want to protect us," Jamil wrote on her own Instagram Wednesday. "And this is just the beginning of our efforts."
Jamil went further, criticizing celebrities like Iggy Azalea, Khloé Kardashian, and Perez Hilton for their promotion of detox teas. The Kardashians have been at the center of the growing backlash against celebrity-sponsored weight loss products advertised on Instagram, which resulted in a shift in Instagram policy, according to Collins.
"If [a Kardashian’s] Instagram post is pulled into the policy of promoting diet products or procedures for sale it will be removed," Collins told the Evening Standard. "The Kardashians are people we continue to have collaborative conversations with, they’ll be made aware of the change."