Nour Mansour, a 28-year-old mother of twin daughters, experienced significant hair shedding after achieving more than three stone of weight loss in less than seven months, primarily attributed to the medication Mounjaro. While initially thrilled with her weight loss journey, which addressed struggles since childbirth and boosted her confidence, a disturbing side effect emerged around six months in. Her once full, hip-length hair began shedding at an alarming rate, transforming from "glossy and thick to dry and frizzy." She reported clumps falling out when running her hands through her hair and noticed thinning at her temples, leading her to wear caps and headbands to conceal it.

Many women have reported similar experiences of hair thinning or shedding when undergoing rapid weight loss or experiencing hormonal changes while on medications like Mounjaro. However, experts clarify that the medication itself is not believed to be the direct cause. Dr. David Fenton, a consultant dermatologist and hair loss specialist at OneWelbeck, explained that rapid weight loss or sudden dietary shifts can lead to deficiencies in essential nutrients required for healthy hair growth. These vital nutrients include iron, vitamin B12, folate, zinc, and vitamin D. When individuals lose their appetite and reduce food intake, they risk not consuming enough of these key vitamins.

A lack of protein can also contribute to the problem, as hair is primarily composed of keratin, a tough, fibrous protein. Insufficient protein intake can make hair weak and brittle. Other side effects reported by GLP-1 users, such as brittle fingernails and slowed nail growth, have also been linked to these nutritional deficiencies. Dr. David Strain, a diabetes expert at Exeter Medical School, highlighted that participants in clinical trials are carefully monitored and maintained on nutrient-rich diets, whereas in real-world scenarios, many individuals may not know how to adequately meet their nutritional needs or identify necessary supplements for overall health.

Dr. Fenton advises anyone concerned about hair loss to consider a blood test, especially those following vegan or vegetarian diets. To boost iron intake, recommended foods include red meat, dark leafy greens like kale and spinach, nuts, and seafood. Dairy products such as yogurt and kefir, along with eggs and wholegrains, are good sources of zinc. Vitamin B12, predominantly found in animal products, is readily available in supplement form.

Normally, approximately 90 percent of hair follicles are in a growth phase, with 10 percent resting. However, stress on the body, whether from illness or significant weight loss, can alter this cycle, pushing a higher percentage of follicles into the shedding phase. Dr. Fenton emphasized that "the more weight you lose, and the faster you lose it, the higher the risk." This condition, similar to postpartum hair loss, is known as telogen effluvium and typically resolves over time. Nevertheless, steps can be taken to minimize damage, including slowing down the rate of weight loss to reduce stress on the body. Nour Mansour herself experienced a turnaround after consulting her GP, beginning supplements, and focusing on a well-balanced diet, which successfully halted the shedding.