Before and after photos are ubiquitous for a reason. They’re what marketers call a “social trigger” — a type of content that prompts those who see it to feel or act a certain way. They make it clear to viewers that one situation (the “after”) is more desirable than another (the “before”).

Think of before and after photos focused on weight loss, for example. If a group of people looked at a single photo of someone standing in a bathing suit, each person in that group might have a different reaction. Some might feel attracted to the person, others might feel indifferent about the person and others might focus on something else entirely ― like what the person is wearing or how the sunset looks behind them.

But if that same photo is shown next to another photo of the same person, in which they wear a similar bathing suit but have a larger body, the reactions of the group looking at the photo become much more uniform. They notice the size of the person’s body in both photos before anything else. That comparison is the trigger.

While before and after photos might work for marketers and content creators, they’re often toxic for the rest of us. Sure, some are harmless — a photo of a dirty plate before it gets cleaned with dish soap versus after, or a messy bookshelf next to a tidied-up one. However, any pair of before and after photos that shows a human being sends a dangerous message: that certain types of bodies (or faces, hair types, skin tones, lip shapes, etc.) are better than others.

Here’s why these types of photos are even more insidious than you think:

“While sometimes well-intentioned, the impact of before and after photos lend to social and body comparisons, which can cause harm to anyone — especially people struggling with body image and eating concerns,” said Chelsea Kronengold, associate director of communications at the National Eating Disorders Association.

Many people seeing these photos will themselves to look more like the “before” than the “after.” And because the whole point of the before-and-after comparison is to say that the “after” is better, they’ll likely end up feeling less-than, or like their bodies need to be “fixed.” Over time, this can lead to real harm.

“Body dissatisfaction and thin-ideal internalization are potential risk factors for all types of eating disorders,” Kronengold said. “People with negative body image are not only more likely to develop an eating disorder, but are also more likely to suffer from depression, isolation, low self-esteem and obsessions with weight loss.”

Before and after photos exist in every corner of social media, but they’re most pervasive in the weight loss space. Often, these posts elicit comments that seem positive, like, “so inspiring!” or “you look great!” But there’s a problematic flip side to these comments: The implication is that the person didn’t look great in their larger body, and that being thinner is always better.

“These subtle and overt messages contribute to weight stigma and perpetuates unhealthy diet culture messages that changing your body, losing weight or being thinner, is viewed as a ‘morally superior’ accomplishment,” Kronengold said.

This weight stigma (discrimination based on a person’s weight) is incredibly pervasive in our society, and it has serious negative effects. A 2018 review in the Journal of Advanced Nursing found that experiencing weight stigma increased a person’s risk of diabetes, eating disturbances, depression, anxiety and body dissatisfaction. It was also linked to an increase in chronic stress and chronic inflammation, and a decrease in self-esteem.

Weight stigma springs from the belief that thinner is better, and that fatness is unhealthy. But that’s not really the case. One 2016 review published in JAMA found that people in the “overweight” body mass index category live the longest. Another 2016 study published in the International Journal of Obesity found that 50% of people classified as “overweight” and nearly percent of people classified as “obese” were metabolically healthy. Meanwhile, 30% of people classified as “normal” weight were metabolically unhealthy.

The relationship between weight and health is incredibly complicated, but it’s fair to say that you can’t determine whether or not someone is healthy by looking at a photo of them.

Kronengold also pointed out that even before and after photos showing weight gain reinforce weight stigma. The eating disorder recovery space is filled with before-and-afters that showcase an extremely thin “before” body next to a less-thin (but still relatively small) “after” body.

“Many of these eating disorder before and after photos send the message that individuals with a history of anorexia [nervosa] and/or a low BMI are the only people impacted by eating disorders,” Kronengold said. “This reinforces the stereotype that eating disorders have a certain ‘look,’ and can alienate people with other eating disorder diagnoses and/or in higher-weight bodies.”

Another massive problem with before-and-afters when it comes to bodies is that they only show two moments in time. Bodies are always changing — even the person posting the photos won’t look like their “after” forever.

“It’s a very real phenomenon that people who post these before-and-after photos often feel boxed in by their visual ‘success stories’ when their bodies inevitably change over time,” said Ashley Seruya, a New York City-based therapist and writer.

And yes, it is inevitable that their bodies will change, because the vast majority of people who lose weight will gain it back within a few years. A 2020 review published in The BMJ found that although diets lead to weight loss and health improvements after six months, that effect disappears at the one-year mark across all types of diets.

Another 2020 review concluded that diets cause more harm than good, since permanent weight loss is rare and negative physical and mental health side effects are common.

Just because someone is smiling in an “after” photo doesn’t mean that they’re mentally healthy. In fact, both Seruya and Kronengold said that it can be damaging to assume that someone has experienced positive life changes just because they “look better.”

“I think it’s almost always going to be dangerous to place our self-worth in something as uncontrollable and unpredictable as the human body,” Seruya said. Because, truthfully, how someone looks is very rarely an indication of their well-being.

“Instead of emphasizing body transformations, we should be celebrating mental health wins, major life events, and accomplishments that have nothing to do with appearance and/or weight,” Kronengold said.