Dr James Fleming is a Sport Nutritionist, academic, and practitioner with over 15 years’ experience working across sport, health, and performance. He is Associate Head of School (Nutrition) at St Mary’s University, London, where he has played a key role in shaping undergraduate and postgraduate education, including leadership of the MSc Applied Sports Nutrition programme.
Since beginning his career in 2008 after graduating in Sport Science from the University of Southampton, James has worked at the intersection of research and applied practice. He holds an MSc in Applied Sports Nutrition and a PhD focused on fuelling adolescent athletes, an area that continues to underpin his research, with a strong emphasis on supporting the health, wellbeing, and performance of young athletes.
Alongside his academic role, James works as a Performance Nutritionist supporting athletes across the full pathway, from grassroots to professional level, across a range of sports including gymnastics, football, tennis, and athletics. His applied experience includes roles with England RFU Women’s U20s and Harlequins Women RFC.
James is a registered Performance Nutritionist (SENR), a Senior Fellow of the Higher Education Academy (SFHEA), and an ISAK Level 3 Instructor Anthropometrist. He delivers body composition training internationally and contributes regularly to practitioner development.
He leads the Adolescent Athlete Research Community (AARC) and hosts the both of which aim to bridge the gap between research and real-world practice. With a growing publication record and regular appearances at international conferences, James is recognised for his work translating evidence into practical strategies that enhance athlete development and performance.
Key qualifications / certifications
PhD / MSc / BSc / PGCE / SENR Practitioner Registration / ISAK L3 Instructor Anthropometrist
Areas of expertise
- Adolescent athlete nutrition: fuelling, growth, maturation, and long-term development
- Translating nutrition science into practical performance strategies
- Health, wellbeing, and resilience in youth sport
- Energy availability, RED-S, and injury risk in athletes
- Applied performance nutrition across team and individual sports
- Specialism in tennis nutrition, with doctoral-level expertise in fuelling, recovery, and performance demands of the sport
- Body composition assessment and monitoring in sport (ISAK methodologies)
- Practitioner education and developing the next generation of sport nutritionists
- Bridging research and real-world practice in sport nutrition
Teaching responsibilities
James predominantly teaches on the MSc in Applied Sports Nutrition, alongside contributions to undergraduate programmes in Nutrition and Nutrition with Sport & Exercise. He also supports teaching across Physiotherapy and other interdisciplinary subjects within the faculty.
Content specialisation
- Applied sports nutrition
- Youth and adolescent athletes
- Athlete fuelling strategies
- Supplement safety and regulation
- Exercise performance nutrition
Research output, publications & media
Previous publications
Lawson, K., & Fleming, J. (2025). Time to ‘Power-Up’ Esports Performance Nutrition: A Systematic Scoping Review . International Journal of Esports, 1(1). Retrieved from
Fleming, J. A., Corr, L. D., Earle, J., Naughton, R. J.,
& Harper, L. D. (2022). Significant energy deficit and suboptimal sleep
during a junior academy tennis training camp.
Pediatric Exercise Science,
1–6.
Fleming, J. A., Naughton, R. J., & Harper, L. D. (2022). Nutrition and the elite and highly trained junior and young adult tennis player: A scoping review. International Journal of Sports Science & Coaching, 1–12. https://doi.org/10.1177/17479541221087687
Fleming, J. A., Field, A., Lui, S., Naughton, R. J., &
Harper, L. D. (2022).
The demands of training and match play on elite and highly trained junior tennis players: A systematic review. International Journal of Sports Science & Coaching, 1–12.
https://doi.org/10.1177/17479541221102556
Truax, S., Fleming, J. A., Cross, B. L., & Grosicki, G.
J. (2022).
Nutritional habits of
adolescent tennis players pre-, during, and post-match play.Minerva Pediatrics.
https://doi.org/10.23736/S2724-5276.22.06878-1
Contribution:
Second author (concept, design, data interpretation, manuscript drafting 50%).
Fleming, J., Ó Catháin, C., Harper, L., & Naughton, R. (2021). Dietary intake and daily distribution of carbohydrate, protein and fat in youth tennis players over a 7-day training and competition period. Journal of Sports Science and Medicine, 20, 413–420.
Ó Catháin, C., Fleming, J., Renard, M., & Kelly, D.
(2020).
Dietary intake of Gaelic football players during game preparation and recovery. Sports, 8(5), 62.
https://doi.org/10.3390/sports8050062
Contribution:
Second author (data analysis, results interpretation ~30%).
Cullen, S., Fleming, J., Logue, D., O’Connor, J., Connor,
B., Cleary, J., Watson, J., & Madigan, S. (2020). Anthropometric profiles of elite athletes. Journal of Human Sport and Exercise.
Contribution:
Co-author (concept/design, data interpretation, manuscript drafting ~30%).
Fleming, J. A., Naughton, R. J., & Harper, L. D. (2018). Investigating the nutritional and recovery habits of tennis players. Nutrients, 10(4), 443.
Media appearances / press features
Can discuss:
- Sports nutrition and fuelling athletic performance
- Nutrition for young athletes
- Diet trends and performance myths
- Supplements and sports science
- Health and nutrition in everyday exercise