After Lauren Aitchison became engaged in March 2022, she began seeing targeted ads for wedding content everywhere, with marketing phrases like “shredding for the wedding” and “bridal boot camp.”

“My Pinterest boards were already quite full,” she joked. “It wasn’t a massive surprise to my algorithm.”

Up until then, Ms. Aitchison, 34, had been inundated by general diet ads as well as wedding ads from bridal jewelry brands, but something switched once she posted about her engagement. “I used to get some weight loss stuff anyway,” said Ms. Aitchison, who lives in Edinburgh. But now, “instead of just intermittent fasting, for example, it was ‘intermittent fasting for your big day,’” she said. “It was specifically mentioning the wedding.”

Social media networks like Instagram and TikTok, along with Google’s search engine, are all platforms for wedding vendors like florists, bakeries and planners to promote their businesses. On Pinterest, for example, many young women create wedding mood boards years before they are even engaged. Many social platforms are turning into de facto search engines, and wedding vendors are compelled to feed those platforms’ algorithms with new ideas.

As a result, there is much more for brides to parse through, and they inadvertently give technology companies access to private details about themselves and their personal lives. That has led to an uptick in wedding-related ads, specifically weight loss ads from diet and wellness companies like Noom, said Katie Paul, the director of the Tech Transparency Project, a nonprofit watchdog group that explores the influence of tech in people’s lives.

For Ms. Aitchison, who searched online for a potential wedding venue just three hours after her engagement, the sudden influx of wedding-related weight loss ads was jarring — and put a damper on the fresh, celebratory glow of her union.

But this is just par for the course with ad algorithms, Ms. Paul said. “The algorithm, we know from the Facebook Papers, for instance, is really critical,” she said. “It’s designed to measure the things that get the most engagement, the things that are the most sensational.”

The Facebook Papers were a collection of company documents that were leaked in 2021 by an internal whistle-blower. They demonstrated that the social network was aware that its app Instagram was harming teenagers’ body image. The algorithms that drive targeted ads aim to show what is meant to elicit the strongest feelings, Ms. Paul said, even if they are negative.

After Facebook said it would remove content that promoted eating disorders and extreme weight loss, the Tech Transparency Project published a report in late 2021 that found that Instagram was still pushing weight loss content. “Many of the recommended accounts explicitly promoted anorexia and bulimia, listing goal weights as low as 77 pounds,” the group said.

Alysia Cole, 34, a wedding stylist in Chicago who often works with plus-size brides, has seen the effect of these ads on her clients, many of whom are recovering from eating disorders and unhealthy relationships with diet culture. The ads, she said, feed the weight-related insecurities that many future brides have, and that many of them developed even before their engagements. “What you see on Instagram is this unspoken thing of, looking your best is equivalent to looking your thinnest,” she said.

Some of the ads focusing on weight loss products and services have become more subtle, Ms. Cole said. It’s not about weight loss anymore — it’s about maintaining “wellness” or “taking care of your health.” Marketing weight loss as health, especially as people pay more attention to personal well-being amid the Covid-19 pandemic, creates a sense of personal responsibility that is harder to ignore than if it were just about aesthetics.

After gyms closed during the Covid-19 lockdown, Jazmine Fries, 25, a wedding planner in San Antonio who was a health care worker at the time, was not able to prioritize working out for a couple of years. Then in the fall of 2021, when she became engaged, she started seeing recommendations for wedding Facebook groups specifically focused on weight loss topics like juice cleanses and advice on how to lose pounds fast.

As a wedding planner, she often fields questions from brides about whether they should buy dresses closer to their wedding date — when they plan to have lost weight — or sooner.

“Naturally you’re going to have more eyes on it,” Ms. Fries said of wedding gowns. “Therefore, it’s much more pressurized in terms of, Am I going to pick this dress because I love it, or because it’s going to photograph on me?”

Ms. Cole and Ms. Fries both agree that a large part of the pressure to lose weight comes from the fact that weddings are photographed and documented on the internet more now than ever before. Weight loss still remains a common aspiration in the wedding industry, they said, and the quiet voice of a targeted ad doesn’t help.

Many brides are cognizant that the ads are based on their online activity, whether it is searching for bridesmaid dresses or posting pictures of their engagement rings. Ms. Paul, 37, who married in September, is cautious about using social media because of her work in tech transparency. Yet, she still received ads selling diet and weight loss programs after she announced her engagement on her Instagram.

“At that point, I hadn’t even thought about planning, I hadn’t been searching anything,” she said. “This is an example of how these platforms push this content to you based on increasingly targeted advertising. They’re tracking you all over the internet.”

While Ms. Paul has seen some fitness ads specifically tailored to grooms, a majority of them overwhelmingly target brides.

When advertisers try to target users with online ads based on their interactions and search history, Ms. Paul said, “extreme weight loss” is one user interest that they can select to focus on. Targeted weight loss ads are a small piece of a much more nefarious pie, she said, and they are designed to stress users out and draw their attention.

“They’re fear ads about what to stress about and things like that,” Ms. Paul said, adding that when it comes to eating disorders, “the algorithms seem to continue to drive people toward the most extreme and harmful” behavior.

Plus-size brides often have fewer ready-to-wear options for clothing and styling in general. But some wedding professionals are working to give brides, especially those who are plus-size, an alternative way to imagine their weddings beyond the traditional one-size-fits-all advice for what’s considered “flattering” on larger bodies. Hair stylists and dressmakers, for example, might provide several different options for plus-size brides instead of just one or two.

“A lot of wedding vendors are being more vocal about their pillars, their personal ethos,” Ms. Cole said. “That includes things like body positivity.”

Despite the rampant weight loss messaging, Ms. Fries believes that the coronavirus pandemic has reframed a lot of personal values as well.

“I feel strongly that people’s perception of what really mattered started to change,” she said, “and so you started to see in 2022 that there was this foundation of, ‘Yes, I may not be the weight I want to be, or I may not be what I was two years ago, but I am stronger.’”