Anything that promotes certain weight loss products or cosmetic procedures with an incentive to buy or a listed price will be hidden from users under 18.
Anything with “miraculous” claims alongside offers such as discount codes will be banned.
Instagram says it wants to ensure its photo-sharing app is a “positive place” following concerns about the impact of dieting, detoxing and cosmetic surgery content on young people.
Just last month, nutritionists told Sky News that certain social media accounts are to blame for a rise in people with eating disorders like orthorexia – when people are obsessed with healthy eating and become starved.
Emma Collins, public policy manager at Instagram, said the company had sought expert guidance to crack down on content that could impact mental health in such a way.
She added that the changes would “reduce the pressure that people can sometimes feel as a result of social media”, while ensuring that Instagram “remains a platform for expression and discussion”.
The move has been welcomed by campaigners, including actress Jameela Jamil.
She has criticised celebrities such as Khloe Kardashian for posting about dietary products on Instagram, and launched an online movement called I Weigh to encourage people to share their achievements regardless of body shape.
Hailing the change in policy as a “huge win”, Jamil said: “Facebook and Instagram taking a stand to protect the physical and mental health of people online sends an important message out to the world.
“I’m thrilled to have been able to work towards this with them, alongside a host of other experts who shed light on the danger of these products.
“Instagram were supportive and helpful when I brought them my protests and petitions; they listened, they cared, they moved so efficiently, and communicated with us throughout the process.”