Experts say rapid weight loss from Mounjaro and other jabs can raise risk of loose skin — but it is not inevitable

A growing number of clinicians warn that the speed of weight loss associated with GLP-1 medications such as Mounjaro can increase the likelihood of loose or sagging skin, but they stop short of saying the drugs themselves directly cause that outcome.

About 1.5 million people are receiving weight-loss injections through the NHS or private clinics in the UK, and millions more are considered eligible, prompting questions about side effects as use rises. Some users who have experienced rapid reductions in body fat describe stretched, saggy or wrinkled skin; others have chosen to embrace those changes publicly. "There isn't really a direct connection between weight-loss jabs and loose skin," said Kiran Jones of Oxford Online Pharmacy, stressing that underlying factors and the pace of weight loss are key.

Several specialists interviewed by reporters said rapid reduction in fat volume can leave insufficient time for the skin to remodel, increasing the risk of laxity. "Unlike traditional weight loss over time, these medications create dramatic reductions in fat volume quickly, leaving insufficient time to remodel," said Dr. Tijion Esho, a cosmetic doctor and aesthetician. He added that people with lower baseline skin elasticity—older adults, for example—are particularly vulnerable.

Clinicians and researchers point to a range of factors that influence whether someone will develop loose skin after weight loss. Genetics play a role, according to Hazim Sadideen, a consultant plastic surgeon at the Cadogan Clinic, who said inherited differences in collagen density and quality affect elasticity. Certain connective tissue disorders such as Ehlers-Danlos syndromes also predispose people to loose or hyperextensible skin.

The length of time a person has carried excess weight is another determinant. "People who have carried excess weight for a long time may also have more stretched or damaged skin," said Dr. Sheila Li, founder of Mediject. Ayesha Bashir, a pharmacist at Chemist4U, added that prolonged obesity can wear out collagen and elastin fibres that normally allow skin to retract after fat is lost.

Experts gave varying numerical thresholds for when loose skin becomes more likely. Dr. David Jack, an aesthetics specialist, said observable loose skin typically follows loss of at least 15 to 20 percent of starting body weight, or a drop of five to eight BMI points, while Dr. Esho suggested that losing more than 20 to 25 percent of body mass in a short time may precipitate sagging.

Sex, age and hormonal changes also matter. Women often have thinner dermis and a higher fat-to-muscle ratio than men, making laxity more apparent, Dr. Li said. Postmenopausal women may face higher risk because lower levels of estrogen are associated with reduced collagen production and skin quality, Dr. Jack added. Basal metabolic rate and muscle mass were cited as additional influences because muscle provides structural support beneath the skin.

Although no method guarantees prevention of loose skin, most experts recommended moderating the pace of weight loss and maintaining or building muscle. Pharmacist Kiran Jones suggested a conservative pace of about 2 percent of total body weight per week or less. Clinicians emphasized strength and resistance training to preserve lean mass, which "gives the skin something to contour to," Dr. Jack said.

Dietary measures included adequate protein intake and nutrients that support collagen production. Dr. Jack recommended about 1.2 grams of protein per kilogram of ideal body weight per day for people losing weight. Hazim Sadideen advised diets that include healthy fats, collagen peptides from foods such as beef, chicken, fish or bone broth, and vitamin C, which assists in collagen synthesis. Several experts also highlighted hydration and sufficient sleep as general supports for skin health.

Specialists noted that lifestyle factors such as smoking, prolonged sun exposure, poor nutrition and dehydration can accelerate collagen breakdown and impair elasticity. "Staying well hydrated is crucial for maintaining skin elasticity," Sadideen said, while Dr. Tina Tian of Stratum Dermatology Clinic Oxford warned that ultraviolet exposure and tobacco use worsen long-term skin quality.

Some people who develop loose skin after rapid weight loss accept it as part of their weight-loss journey. Weight-loss influencer Lexi Reed, 34, told reporters she remains confident in swimwear despite being "covered in loose skin," saying it reflects the battles she has faced and won.

Surgeons and dermatologists said that, where laxity is pronounced and affects quality of life, surgical and clinic-based options exist to remove or tighten excess skin, but those interventions carry their own risks and costs and were not the primary focus of the experts consulted. Physicians emphasized individualized care decisions and recommended that patients discuss expectations, timelines and strategies to preserve skin health with prescribing clinicians and qualified dermatology or plastic-surgery teams before and during treatment with weight-loss medications.