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

NCT07122778 | Not Yet Recruiting

• 2 other identifiers: 6854-11590345572
• Study Type: interventional
• Target: 20
• Locations: 1 country
• Sites: 1

Brief Summary

Recent research has suggested that increasing levels of physical activity are associated with a reduction in the independent components that contribute to total energy expenditure (such as resting metabolic rate and non-exercise movement) - this occurs to conserve energy required for physical activity where energy provision becomes scarce. There are potential deleterious health and performance consequences of a reduced energy supply to fundamental metabolic processes, putting individuals regularly undertaking high levels of physical activity, such as endurance athletes, at risk. However, this association is largely based on observational data in only moderately active populations, and it is currently unclear what role energy balance status and biological sex has on this relationship. This research intends to address these unknowns by assessing the impact of diet-induced manipulation of energy balance (conditions of energy deficit and energy surplus) in individuals undertaking habitually high levels of physical activity on independent components of total energy expenditure (resting metabolism, exercise and non-exercise movement). Male and female athletes conducting regular moderate-to-high training volumes will undertake a randomised crossover study with a 7-day state of energy deficit and a 7-day state of energy surplus. Participants will continue to live and train as normal, but their diet will be controlled by specific food provision over the intervention periods in order to facilitate both conditions. Independent components of energy expenditure, markers of health, metabolism and performance will be measured to allow for comparison of conditions.

Conditions

Energy Balance; Energy Deficit; Low Energy Availability; Relative Energy Deficiency in Sport

Keywords

energy deficit; energy balance; energy availability; physical activity

Outcome Measures

Primary Outcomes (1)

• Resting metabolic rate (RMR) in kcal/day

  The effect of a 7-day period of energy expenditure-matched diet-induced energy deficit versus energy surplus on RMR. Measured via indirect calorimetry using the Douglas bag method. Expired gas will be collected in a seated, fasted state under thermoneutral conditions, and oxygen consumption and carbon dioxide production will be used to calculate energy expenditure.

  Measured at lab visits 1-5 (baseline and pre- and post-interventions) from 0 to 12 weeks.

Secondary Outcomes (36)

• Total energy expenditure (from doubly labelled water) in kcal/day

  Measured during both 7-day interventions starting at approximately week 4 and week 9.

• Total energy expenditure ( from sum of independent components of energy expenditure) in kcal/day

  Measured during both 7-day interventions starting at approximately week 4 and week 9

• Peripheral blood mononuclear cell (PBMC) mitochondrial respiration

  Measured pre- and post-exercise at visits 2/3 (pre- and post-intervention 1) and visits 4/5 (pre- and post-intervention 2), approximately weeks 4-12.

• Sub-maximal exercise performance (during steady-state treadmill exercise)

  Measured at lab visits 1-5 (baseline and pre- and post-interventions) from 0 to 12 weeks.

• Free T3 in pmol/L

  Measured at lab visits 2-5 (pre- and post-interventions) from 4 to 12 weeks.

Study Arms (2)

Energy deficit

EXPERIMENTAL

Diet-induced 50% energy deficit (based on estimated average total daily energy expenditure) by allocation of pre-made meals and snacks over 7-days

Dietary Supplement: Controlled energy-deficit diet

Energy surplus

EXPERIMENTAL

Diet-induced energy surplus (approximately 500-1000kcal/day) achieved by allocation of additional snacks to be consumed on top of habitual free-living diet, to avoid inadvertent energy deficit

Dietary Supplement: Habitual diet with surplus snacks

Interventions

Controlled energy-deficit diet DIETARY_SUPPLEMENT

Participants receive a prepared diet providing approximately 50% of their estimated daily energy expenditure to induce a sustained energy deficit

Also known as: Energy deficit

Energy deficit

Habitual diet with surplus snacks DIETARY_SUPPLEMENT

Participants continue their normal diet with the addition of high-calorie snack items to achieve an approximate daily energy surplus

Also known as: Energy surplus

Energy surplus

Eligibility Criteria

• Age: 18 Years - 49 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Self-identified endurance-trained sport participants
• Training volume: \>7 hours per week endurance training
• Training frequency: at least 5 days per week

You may not qualify if:

• 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

Sponsors & Collaborators

• University of Bath: lead
• Royal Centre for Defence Medicine: collaborator

Study Sites (1)

University of Bath

Bath, BA2 7AY, United Kingdom

Location

MeSH Terms

Conditions

Relative Energy Deficiency in Sport; Motor Activity

Condition Hierarchy (Ancestors)

Feeding and Eating Disorders; Mental Disorders; Behavior

Central Study Contacts

Joshua J Bakker-Dyos, BSc(Hons) MBChB

CONTACT

+447740191473; jbd28@bath.ac.uk

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principal Investigator

Study Record Dates

• First Submitted: April 14, 2025
• First Posted: August 14, 2025
• Study Start: August 1, 2025
• Primary Completion (Estimated): August 1, 2026
• Study Completion (Estimated): May 1, 2027
• Last Updated: August 14, 2025

Record last verified: 2025-08

Locations

GB (1)