A Londoner who ran the London Marathon for the first time in 2025 has shared three mistakes she made, hoping to help other first-timers avoid similar pitfalls. Carla Casadei, founder of Casadei Foods, took to TikTok to recount her errors after completing the 26.2-mile race.
Casadei's first mistake was wearing a running vest over her t-shirt. While she had trained in the vest without issues, the warm weather on race day meant water was sprayed over participants, and she also doused herself to cool down. The moisture made the vest significantly heavier. "This was weighing like five kilos," she said. "It was so heavy." She recommends using a belt instead, which can carry essentials without becoming waterlogged.
Her second mistake involved a running belt that held her marathon bib. Casadei explained that the belt rotated around her body during the race, shifting the bib from the front to her side or back. She advises fastening the bib with pins in the traditional way to avoid this problem.
The third and worst mistake, according to Casadei, was avoiding energy gels. Many runners use gels to replenish glycogen stores during long runs, but she sought a 'healthier' option and ate fresh dates instead. "So there was me and my little dates," she said, showing footage of herself eating a date while running. She nearly passed out, acknowledging that gels are widely used for a reason. Her advice: "On marathon day, just stick to the basics, just have your gels, take for every 5k after every 10k, just really the bare minimum, because what you need the most is to be free so you can run at your best."
