Katie Sturino says she spent 6 million hours wishing she could shrink herself and disappear, and approximately 850 years considering how much exercise she had to do to cancel out the calories she’d consumed. The estimates are tongue-in-cheek, of course, but they underscore her more serious point: What a waste of time.

“You pay so much money, then go on vacation — or take a day off and go to the beach — and spend it, what, hiding? Feeling uncomfortable and looking at yourself saying, ‘Oh, I need to go to the gym more?’ ” said Sturino, author of “Body Talk,” which published in May and is part memoir, part manual on body acceptance. “No! Go swimming.”

Sturino started body shaming herself at a young age: She was voted “heaviest kid” in her class at age 5 and spent decades feeling like the biggest person in the room. Throughout her adult life, she worried that she wouldn’t fit into her seat: at the movie theater, at tiny trendy restaurants, at the dentist or on an airplane. But in her 30s, she had a eureka moment: “My body is not the problem,” she realized — a stunning concept after a lifetime of feeling like something was wrong with her, and that her size determined her worth.

Why do so many of us, like Sturino, engage in such negative self-talk? And what can we do about it, especially as we emerge from a global pandemic during which so many of us have put on weight?

Nina Savelle-Rocklin, a Los Angeles-based psychoanalyst who specializes in food, weight and body-image issues, says it’s difficult for many Americans not to internalize the “pervasive sense that there’s something wrong with you” given the near-constant stream of toxic messaging in our culture, much of which is tied to the multibillion-dollar weight-loss industry. Consider the obsession with “skinny” everything, including lattes; the focus on “beach-ready” bodies; the endlessly popular before-and-after diet photos. In June, for example, photos of the singer Camila Cabello at the beach went viral, with droves of social media users making spiteful comments about how she looked in a bikini. And on TikTok, thousands of “What I Eat in a Day” videos, often posted by thin young women, promote the idea that if you eat like them, you’ll be able to look like them, even though genetically, we can’t all achieve specific body types.

Self-shaming is a destructive mind-set, Savelle-Rocklin said. “There’s a split between us and our bodies that happens when we body shame ourselves — ‘I’m against my body, I need to whip my body into shape, I need to change my body.’ And that is antithetical to a sense of well-being.”

A. Janet Tomiyama, an associate professor of health psychology at the University of California at Los Angeles, said some medical ethicists think fat shaming can be used to motivate people to lose weight. The idea is that it provides a “kick in the pants” to exercise more and eat better — but her research shows the opposite is true. “We know that people who experience body shaming are at a much higher risk for both depression and anxiety disorders,” she said. “It’s easy to see how feeling bad about yourself could lead to more serious emotional troubles.”

Self-shaming can start in young children, as Sturino’s story illustrates, and persist through old age. Both men and women are susceptible, Tomiyama said. But if you inflict body shame on yourself, there is hope. “It’s never too late” to start overcoming your shame, or too early to start working toward body acceptance, Sturino said.

Here are tips on how to start the process.

Cultivate curiosity and compassion. The next time you start criticizing yourself, “take a split-second pause, step back and ask yourself where it’s coming from,” said Jenny Weinar, a Philadelphia-based licensed clinical social worker and therapist who specializes in disordered eating and body image. Whose voice are you hearing? “That voice could be someone specific in your life, like a caregiver or partner, or it could just be the male gaze or patriarchy,” she said. “But starting to put that distance between ourselves and the voice helps us recognize that, okay, that’s not me, that’s something I learned — and if I can learn it, I can unlearn it.”

Another emotion to work on, Weinar said, is compassion: Even when her clients are in the process of unlearning their shaming tendencies, they often feel extra bad about their bodies. “Channeling that super compassionate voice that we needed at some point in the past can be really powerful,” she said.

Write down everything your body does for you. Ragen Chastain, a Los Angeles-based fat activist who holds the Guinness World Record for heaviest woman to complete a marathon, spent a long time feeling angry at her body for not looking like a Photoshopped image on the Internet. Then, she realized she hadn’t spent a minute being grateful for its powers. “I just listed off everything I could think of that my body did for me,” she said. “On a granular level, even breathing and blinking and waste management, but also smiling or hugging.”

Going forward, every time she experienced a negative thought about her body, she replaced it with something from her gratitude list. If she started to spiral into shame, she’d quickly correct herself: “ ‘No, actually, thank you for breathing, because you’re knocking that out of the park, and I really appreciate it,’ ” she said. “It sounds super hokey, but in a period of months it fundamentally changed my relationship with my body.”

Say “nope.” One of Sturino’s favorite ways to combat body shaming is to simply yell “nope!” inside her brain. If, for example, you’re standing in front of the mirror bemoaning the too-big hips that are “ruining” your life, cut that thought off with a big “nope” instead. “It’s all about stopping that continued negative dialogue so that you can break the habit,” said Sturino, who hosts the Boob Sweat podcast. She’s also the founder of Megababe, a skin care line devoted to solving problems she was once embarrassed about, such as thigh chafe.

Fight back against fat stigma. Chastain recalls realizing that she had spent decades fighting her body on behalf of fat phobia. She decided that instead, she was going to fight weight stigma on behalf of her body. “Fat phobia is real,” she said. “This is not in our heads. We are living in a world that says a thinner body is a better body.”

In addition to not body shaming yourself or anyone else, ask yourself what assumptions you make about fat people — and then dismantle those beliefs. Think carefully about what language you use; for example, “good” and “bad” moralize food. Other ways to fight fat phobia include no longer supporting media that run headlines about the worst bikini bodies or dole out harmful weight-loss content. Boycott companies that peddle “detox” products, and don’t buy clothes from shops that exclusively use rail-thin mannequins. Consider getting involved with the Health At Every Size movement, which promotes weight neutrality. “Understand that [diet] culture is toxic, and stop participating in it,” Chastain said.

Clean out your closet. Sturino had what she calls a “failure dress” — a very expensive garment that barely zipped. She kept it for a long time, hoping she would eventually fit into it, because we often nurture “the expectation that our current body is a temporary body,” she said. But every time you see something that doesn't fit you anymore in your closet, it can make you think, “I need to lose weight, I need to go on a diet.” Instead, donate the clothing that no longer fits you, and fill your closet with selections you love that fit you in your current size, Sturino suggested.

Consider getting support from a therapist. Some people can overcome body shame on their own; others need to work with a professional (there are therapists who specialize in body image issues). People who underwent trauma that contributed to their body shame — which can include growing up in a larger body or being put on a diet as a child — often benefit from the structure and support of therapy, Weinar said, because such experiences “can have lasting effects on someone’s sense of safety and acceptability in their body.” Other people simply get stuck in their journey to body acceptance, and having dedicated time and space to address it can be useful.

Treat yourself like you would treat another person. The next time you lash out at your stomach, arms or legs, ask yourself: “Would I ever say that out loud to another person?” As Cindy Bulik, founding director of the University of North Carolina Center of Excellence for Eating Disorders, put it: “Would you ever go up to another person and say, ‘You’re so fat,’ or ‘Your arms are so flabby’?” Most likely, she said, “you’re infinitely more rude to yourself than you ever would be to another person.”

Angela Haupt is a freelance writer and editor. Follow her on Twitter @angelahaupt.