NCT07847658

Brief Summary

Type of Study: Clinical Trial Goal: The goal of this clinical trial is to investigate whether combining the Buchinger Wilhelmi prolonged fasting program with a structured exercise program can improve physical fitness, body composition, cardiometabolic health, sleep quality, and health-related quality of life. The study will also investigate metabolic responses to prolonged fasting and whether these responses are influenced by exercise. Participant Population/Health Conditions: The study will involve adults attending the Buchinger Wilhelmi Clinic who undergo the prolonged fasting program and meet the study eligibility criteria. Main Questions:

  • Does structured exercise performed before and/or during prolonged fasting enhance its effects on physical fitness, body composition, and cardiometabolic health?
  • Does structured exercise improve sleep quality and health-related quality of life during prolonged fasting? Participants Will:
  • Undergo the Buchinger Wilhelmi prolonged fasting program.
  • Choose whether to complete an online exercise program before the clinical stay and/or a supervised exercise program during fasting.
  • Undergo physiological, physical fitness, and body composition assessments before and after the intervention.
  • Provide blood samples to assess cardiometabolic and metabolic responses.
  • Complete assessments of sleep and health-related quality of life. Comparison Groups: Researchers will compare the four study conditions to determine whether structured exercise performed before and/or during prolonged fasting enhances the physiological, metabolic, and functional effects of the Buchinger Wilhelmi fasting program.

Trial Health

63
Monitor

Trial Health Score

Automated assessment based on enrollment pace, timeline, and geographic reach

Enrollment
100

participants targeted

Target at P50-P75 for not_applicable

Timeline
37mo left

Started Jan 2027

Typical duration for not_applicable

Geographic Reach
1 country

1 active site

Status
not yet recruiting

Health score is calculated from publicly available data and should be used for screening purposes only.

Trial Relationships

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Study Timeline

Key milestones and dates

First Submitted

Initial submission to the registry

September 17, 2026

Completed
12 days until next milestone

First Posted

Study publicly available on registry

September 29, 2026

Completed
3 months until next milestone

Study Start

First participant enrolled

January 1, 2027

Expected
3 years until next milestone

Primary Completion

Last participant's last visit for primary outcome

January 1, 2030

Same day until next milestone

Study Completion

Last participant's last visit for all outcomes

January 1, 2030

Last Updated

September 29, 2026

Status Verified

September 1, 2026

Enrollment Period

3 years

First QC Date

September 17, 2026

Last Update Submit

September 23, 2026

Conditions

Fasting ConditionsMetabolic Health

Keywords

Prolonged fastingBuchinger Wilhelmi fastingPhysical exerciseCardiometabolic healthPhysical fitness

Outcome Measures

Primary Outcomes (1)

  • Handgrip Strength

    Change from baseline in mean bilateral handgrip strength (kg) to the end of the fasting period, assessed using a handgrip dynamometer. For each hand, three trials will be performed and averaged. The mean values obtained for the right and left hands will then be averaged to obtain one bilateral handgrip strength value per participant.

    Baseline and Day 4 to Day 28 (final fasting day, depending on participant)

Secondary Outcomes (17)

  • Fasting Blood Glucose

    Baseline and Day 4 to Day 28 (final fasting day, depending on participant)

  • Fasting Insulin

    Baseline and Day 4 to Day 28 (final fasting day, depending on participant)

  • LDL Cholesterol

    Baseline and Day 4 to Day 28 (final fasting day, depending on participant)

  • HDL Cholesterol

    Baseline and Day 4 to Day 28 (final fasting day, depending on participant)

  • Triglycerides

    Baseline and Day 4 to Day 28 (final fasting day, depending on participant)

  • +12 more secondary outcomes

Study Arms (4)

Prolonged fasting

EXPERIMENTAL

Participants will undergo the Buchinger Wilhelmi prolonged fasting program for at least 4 consecutive days without completing the study-specific online exercise program before the clinical stay or the supervised exercise program during fasting.

Behavioral: Buchinger Wilhelmi prolonged fasting

Prolonged fasting + supervised exercise

EXPERIMENTAL

Participants will undergo the Buchinger Wilhelmi prolonged fasting program for at least 4 consecutive days and participate in the study-specific supervised exercise program during the fasting period. Participants will not complete the online exercise program before the clinical stay.

Behavioral: Buchinger Wilhelmi prolonged fastingBehavioral: Supervised exercise program during prolonged fasting

Online exercise + prolonged fasting

EXPERIMENTAL

Participants will complete a 21-day study-specific online exercise program before the clinical stay and subsequently undergo the Buchinger Wilhelmi prolonged fasting program for at least 4 consecutive days without participating in the supervised exercise program during fasting.

Behavioral: Buchinger Wilhelmi prolonged fastingBehavioral: Online exercise program

Online exercise + prolonged fasting + supervised exercise

EXPERIMENTAL

Participants will complete a 21-day study-specific online exercise program before the clinical stay and subsequently undergo the Buchinger Wilhelmi prolonged fasting program for at least 4 consecutive days combined with the study-specific supervised exercise program during fasting.

Behavioral: Buchinger Wilhelmi prolonged fastingBehavioral: Online exercise programBehavioral: Supervised exercise program during prolonged fasting

Interventions

Buchinger Wilhelmi prolonged fastingBEHAVIORAL

Participants will undergo the medically supervised Buchinger Wilhelmi prolonged fasting program for at least 4 consecutive days. During fasting, participants will receive approximately 200-250 kcal/day, primarily from vegetable juices and vegetable broth, together with non-caloric fluids.

Online exercise + prolonged fastingOnline exercise + prolonged fasting + supervised exerciseProlonged fastingProlonged fasting + supervised exercise
Online exercise programBEHAVIORAL

Participants will complete a 21-day study-specific remotely delivered exercise program before admission to the Buchinger Wilhelmi Clinic. The program provides structured exercise training before the prolonged fasting period.

Online exercise + prolonged fastingOnline exercise + prolonged fasting + supervised exercise
Supervised exercise program during prolonged fastingBEHAVIORAL

Participants will complete a study-specific supervised exercise program during the prolonged fasting period at the Buchinger Wilhelmi Clinic. Exercise sessions will be conducted under professional supervision and adapted to participants' individual physical capacity.

Online exercise + prolonged fasting + supervised exerciseProlonged fasting + supervised exercise

Eligibility Criteria

Age18 Years - 80 Years
Sexall
Healthy VolunteersYes
Age GroupsAdult (18-64), Older Adult (65+)

You may qualify if:

  • Men and women aged 18-80 years.
  • Undergoing the Buchinger Wilhelmi prolonged fasting program at the Buchinger Wilhelmi Clinic in Marbella for at least 4 consecutive days.
  • Medically eligible to undergo prolonged fasting and to complete the study assessments.
  • For participants choosing an exercise condition, medically eligible to participate in the corresponding exercise program.
  • Able to understand the study procedures and provide written informed consent.

You may not qualify if:

  • Any medical condition or functional limitation that significantly restricts mobility or prevents safe completion of the study assessments or, when applicable, the exercise program.
  • Pregnancy or breastfeeding.
  • Cognitive or communication impairment that prevents adequate understanding of the study procedures or provision of informed consent.
  • Concurrent participation in another interventional study that could interfere with the study procedures or outcomes.

Contact the study team to confirm eligibility.

Sponsors & Collaborators

Study Sites (1)

Universidad de Almería

Almería, Almeria, 04131, Spain

Location

MeSH Terms

Conditions

Motor Activity

Condition Hierarchy (Ancestors)

Behavior

Central Study Contacts

Borja Martínez Téllez, PhD

CONTACT

+34 950215334borjammt@ual.es

Study Design

Study Type
interventional
Phase
not applicable
Allocation
NON RANDOMIZED
Masking
NONE
Purpose
OTHER
Intervention Model
PARALLEL
Model Details: This study will consist of a non-randomized clinical trial including adults undergoing the Buchinger Wilhelmi prolonged fasting program. Participants will self-select whether to complete an online exercise program before the clinical stay and whether to participate in a supervised exercise program specifically designed for the fasting period. This will result in four parallel groups: prolonged fasting alone; prolonged fasting plus supervised exercise; online exercise followed by prolonged fasting alone; or online exercise followed by prolonged fasting plus supervised exercise. During prolonged fasting, participants will receive approximately 200-250 kcal/day. Participants will be enrolled prospectively and continuously as they attend the clinic.
Sponsor Type
OTHER
Responsible Party
PRINCIPAL INVESTIGATOR
PI Title
Principal Investigator

Study Record Dates

First Submitted

September 17, 2026

First Posted

September 29, 2026

Study Start (Estimated)

January 1, 2027

Primary Completion (Estimated)

January 1, 2030

Study Completion (Estimated)

January 1, 2030

Last Updated

September 29, 2026

Record last verified: 2026-09

Data Sharing

IPD Sharing
Will share
Shared Documents
STUDY PROTOCOL, ICF, CSR
Time Frame
5 years after publishing the data
Access Criteria
Everybody
More information

Locations

ES(1)