Nour Mansour, a 28-year-old mother of twins, experienced a significant transformation after losing over three stone in less than seven months with the aid of Mounjaro. Initially delighted by her rapid weight loss and boosted confidence, she soon encountered a distressing side effect: severe hair shedding and thinning. Her once-full, hip-length hair began falling out in clumps, turning from glossy and thick to dry and frizzy, particularly noticeable at her temples, leading her to cover it with caps and headbands.

This alarming hair loss is not an isolated incident; many women undergoing rapid weight loss or experiencing hormonal changes due to medications like Mounjaro have reported similar issues. However, experts clarify that the medication itself is not the direct cause. Dr. David Fenton, a consultant dermatologist and hair loss specialist, explains that rapid weight loss or sudden dietary shifts can lead to deficiencies in essential nutrients required for healthy hair growth. These include vital elements such as iron, vitamin B12, folate, zinc, and vitamin D. When individuals reduce their appetite and food intake, they risk missing out on these crucial vitamins and minerals.

A lack of protein is also a significant contributing factor, as hair is primarily composed of keratin, a tough, fibrous protein. Insufficient protein intake can render hair weak and brittle. Furthermore, other side effects observed in 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, highlighted that during clinical trials, participants are typically on closely monitored, nutrient-rich diets, a practice often not replicated in real-world scenarios where users may not know how to adequately meet their nutritional needs or identify necessary supplements.

For those concerned about hair loss, Dr. Fenton recommends considering a blood test, especially for vegans and vegetarians who may be more prone to certain deficiencies. To boost iron intake, dietary recommendations include red meat, dark leafy greens like kale and spinach, nuts, and seafood. Good sources of zinc can be found in dairy products such as yogurt and kefir, eggs, and wholegrains. Vitamin B12, predominantly found in animal products, is also widely available in supplement form.

Dr. Fenton elaborated on the hair growth cycle, noting that typically, about 90 percent of hair follicles are in a growth phase, while 10 percent are resting. However, when the body experiences stress—whether from illness or significant weight loss—this cycle is disrupted, pushing a higher percentage of follicles into the shedding phase. He stressed, "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 usually resolves over time. Fortunately, certain steps can help minimize damage, including slowing down the rate of weight loss to reduce bodily stress. Nour Mansour herself experienced a positive turnaround after consulting her GP, incorporating supplements, and focusing on a nutritious diet, which ultimately halted the shedding.