Impact of Diet-induced Change in Energy Balance on Metabolism in Endurance Athletes

Launched by UNIVERSITY OF BATH · Aug 11, 2025

Keywords

ClinConnect Summary

This clinical trial is looking at how changes in diet affect energy use and metabolism in endurance athletes—people who regularly do long-duration exercise like running or cycling. Researchers want to understand what happens when athletes either eat less than they burn (energy deficit) or eat more than they burn (energy surplus) while keeping up their usual training. The goal is to see how these different eating conditions impact the body’s energy spending during rest, exercise, and everyday movement, and how this might affect overall health and performance.

To take part, you need to be an endurance athlete who trains at least 7 hours a week, spread over 5 or more days. The study will last two weeks, with one week of controlled lower calorie intake and one week of higher calorie intake, while you continue your normal training. Your meals will be provided to make sure the diet matches the study needs. The researchers will measure how your body uses energy, along with health and performance markers. This study is open to both men and women who meet the criteria, but people with certain health conditions, injuries, or specific diets won’t be eligible. If you qualify, you can expect a carefully monitored but otherwise normal training routine with close attention to diet and energy use.

Gender

ALL

Eligibility criteria

• Inclusion Criteria:
• • Self-identified endurance-trained sport participants
• • Training volume: \>7 hours per week endurance training
• • Training frequency: at least 5 days per week
• Exclusion Criteria:
• • Diagnosis of Relative Energy Deficiency in Sport (REDs)
• • Active eating disorder (EDE-Q)
• • Active flare of a chronic disease (e.g. inflammatory bowel disease)
• • Type 1 or 2 diabetes mellitus
• • Untreated or undergoing active treatment of anaemia (any cause)
• • Current injury which precludes undertaking high volume endurance training
• • Individuals following a habitual low-carbohydrate, high-fat diet
• • Any medical diagnosis which precludes intense exercise (e.g. untreated cardiac arrhythmia)
• • Allergy or intolerance to study foods
• • Blood donation within preceding 8 weeks of study start date
• • Use of medications that affect substrate utilisation (e.g. statins, corticosteroids, thyroxine, HRT)
• • For females: current pregnancy, breastfeeding within past 6 months or post-menopausal
• • Unable to undertake a treadmill running test
• • Participation in any research study in the past 8 weeks
• • Participation in a research study within the past year involving more than one DEXA scan
• • Unable to provide informed consent due to impaired cognitive capacity or decision-making ability