The global body-positivity movement that defined much of the 2010s is facing a profound test in the age of powerful new weight-loss drugs.
A decade ago, plus-size model Tess Holliday made headlines when her Instagram campaign #EffYourBeautyStandards went viral, earning her a People magazine cover. Pop culture also embraced size diversity, with Meghan Trainor’s All About That Bass and Lizzo’s Juice promoting confidence in larger bodies.
Today, however, the cultural tide appears to be turning. Both Trainor and Lizzo have since lost weight, with Trainor publicly crediting the diabetes and weight-loss drug Mounjaro, a medication similar to Ozempic. On social media, a new trend known as “SkinnyTok” has taken off, generating more than 500,000 TikTok posts. The US National Alliance for Eating Disorders has warned that the hashtag “glorifies thinness and vilifies weight gain.”
The rise of injectable drugs such as Ozempic, Wegovy and Mounjaro has made significant weight loss more achievable than ever, particularly for people who can afford the treatments. For many doctors, the results are remarkable: US obesity rates have begun to decline for the first time in decades, and some researchers believe the medications are playing a key role.
Yet a growing group of scientists and clinicians caution that equating weight loss with health can be misleading — and in some cases harmful. They argue that fat is not simply a disease to be eliminated, but a complex and sometimes protective part of the human body.
“Your fat tissue is not all evil. It serves a purpose,” said Professor Francesco Rubino, Chair of Metabolic and Bariatric Surgery at King’s College London.
Why fat is not just a problem
Fat tissue, Rubino explains, performs essential biological functions. It cushions bones and joints, meaning people with very low levels of body fat — particularly older adults — may face a higher risk of fractures from falls. It also acts as an energy reserve, helping the body cope during periods of illness, injury or inadequate food intake.
This so-called “overweight paradox” has been observed in medical studies showing that patients with a small amount of extra weight sometimes recover better from major surgery, cancer treatment or time in intensive care.
“When you have to fend off a disease, then having a little bit of extra fat is actually not bad for you,” Rubino said.
That does not mean excess weight is harmless. For some people, it can worsen joint pain, restrict breathing, increase fatigue and raise the risk of conditions such as type 2 diabetes, heart disease and liver disease. “Sometimes even a physiological process that is meant to be protective can end up causing harm,” Rubino noted.
When losing weight may be risky
There are also times when weight loss is actively discouraged. People preparing for surgery, undergoing serious medical treatment or recovering from illness may benefit from extra energy stores rather than strict dieting. Pregnancy is another clear example.
“The baby is like a parasite in the body that will be sucking up all your nutrients,” said Dr Dimitrios Koutoukidis, a Nuffield dietitian and associate professor at the University of Oxford. “To make sure it develops fully, you want to make sure that you have enough calories in your body.”
Koutoukidis added that people who are underweight, or already within a healthy weight range, have no medical reason to try to slim down.
Is obesity always a disease?
The assumption that people in larger bodies should always aim to lose weight is increasingly being challenged. In January 2025, Rubino led a Lancet Commission that proposed a more nuanced way of defining obesity.
The report distinguished between “clinical obesity” — where excess fat directly impairs the function of organs such as the heart, liver or kidneys — and “preclinical obesity,” where a person carries extra weight but shows no current signs of illness.
“If there is no evidence of organs malfunctioning, it’s hard to say that’s a disease,” Rubino said. “Any disease must cause illness.”
Under this framework, weight-loss treatments such as medication, diet or surgery should be used primarily when obesity is already harming health, rather than automatically prescribed based on body size alone.
The hidden costs of rapid weight loss
Even for those who do pursue weight loss, the risks can be substantial. Bariatric surgery, which alters the digestive system to reduce appetite, can lead to complications ranging from nausea and pain to blood clots and stomach leaks.
GLP-1 drugs like Ozempic and Wegovy, which mimic hormones that control hunger and blood sugar, commonly cause side effects including nausea, vomiting, diarrhoea, constipation and nutritional deficiencies. In rare cases, they can trigger stomach paralysis.
Crash dieting brings its own dangers. “You need a set amount of protein and fat to function normally,” Koutoukidis said, warning that overly restrictive diets can lead to muscle loss, weakness and long-term health problems even when people take supplements.
A psychological burden
Beyond the physical risks, weight loss can take a heavy emotional toll. Rubino said many of his patients blame themselves if they do not achieve dramatic results after surgery or medication.
“They think there is something wrong with their moral fabric, which is not true. It’s just the way biology works,” he said.
Most of his patients never reach their “ideal” weight, he added, but their health often improves dramatically. Pushing for further weight loss, he argued, may bring little benefit and unnecessary harm.
As powerful new drugs reshape both bodies and beauty standards, health experts are urging a shift in focus — away from the number on the scale and toward the overall well-being of each individual. In the post-Ozempic era, they say, thinner is not always healthier.
