Diet, Healthy, Body WeightPRNCT06263725
Protein Restriction (PR) for Weight Loss
A study testing Restricted dietary protein and Habitual diet in people with Diet, Healthy, Body Weight, run by University of Copenhagen at 1 site in Denmark.
Trial summary
Prolonged dietary protein restriction has been shown to increase energy expenditure in mice simultaneously with an increase in plasma FGF21 levels. In overfeeding studies, a protein-restricted diet reduces weight gain in both mice and humans compared with normal and high-protein diets. Read more about this study
- Who is it for?
- Ages 25 to 45 years, men onlyHealthy volunteers can take part
- Conditions the study is for
- Diet, Healthy, Body Weight
- What is being tested?
- Restricted dietary protein and Habitual diet
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 15 participants
- Where
- 1 siteDenmark
- Study dates
- 1 Oct 2021to 31 Dec 2023
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 25 to 45 years
- Men only
- Healthy volunteers accepted
- Adult
Who may be able to join
- BMI between 26 and 32 Low physical activity level Non-smoker Not using snuff Not suffering from diabetes, hypertension, or any daily medication use High protein intake (≥1,5 g/kg body weight/day)
Who cannot join
- -
Trial locations and contacts
1 site in 1 country.
About this study
Prolonged dietary protein restriction has been shown to increase energy expenditure in mice simultaneously with an increase in plasma FGF21 levels. In overfeeding studies, a protein-restricted diet reduces weight gain in both mice and humans compared with normal and high-protein diets. Further, in energy balance studies, when lean men are provided with a protein-restricted diet for five weeks, an increase in energy intake was necessary to obtain their body weight. However, whether the effect of a protein-restricted diet is the same when consumed by overweight to obese men has divergent results in both mice and humans.
Read the detailed description
The present study is a randomised intervention study. Inclusion criteria for the study are healthy males age between 25 and 45 years, BMI between 26 and 32, low physical activity level (low aerobic capacity with a VO2 - peak of 30 ± 10 mL/min/kg), non-smoker, not using snuff, not suffering from diabetes, hypertension, or any daily medication use and a high dietary protein intake (≥1,5 g/kg body weight/day). Before the intervention period, the participants complete a two-week run-in period. The run-in period is designed to collect more detailed information about the participant's habitual diet, body weight, and physical activity pattern, as well as habituate the participants in the various tasks they have to complete during the intervention. Then a five-week intervention period is initiated where the participants are randomized to follow one of the following diets for 5 weeks: 1) a diet reduced in protein, replaced by primary carbohydrates (11 E% Protein, 50 E% carbohydrates, 37 E% fat), and 2) a control diet comprising habitual protein content (21E% Protein, 40 E% carbohydrates, 37 E% fat).
In the five-week intervention period, all food and drinks (besides water and coffee) are provided for the participant. All food is weighed to 1 gram of accuracy in meal portions for a seven-day cycle and is delivered to the participant.
During the intervention the volunteers participate in six test days, one every week during the intervention. 48 hours prior to the weekly test, the participants are asked to abstaine from vigorous physical activity. On all the test days, the participants arrive in the morning in a fasted state (no food or drink after 10 pm the night before) by passive transportation.
On the first test day (WT0), body composition is determined by DXA scan, and the total body water content is measured using bioimpedance analysis. Then resting metabolic rate is measured. Still, in the supine position, a blood sample is obtained from an antecubital vein. Biopsies are taken at baseline and at the end of the intervention (WT5). A fat biopsy is obtained from periumbilical subcutaneous adipose tissue and a muscle biopsy from the vastus lateralis muscle. On test day 3, halfway through the intervention, body composition, body water, and resting metabolic rate are measured, and blood is sampled from an antecubital vein. On week tests 1, 2, and 4, resting metabolic rate is measured, and blood sampled. At all visits to the institute, body weight is also measured.
During the intervention the participants wear a Sens motion sensor to monitor daily activity level.
- Conditions
- Diet, Healthy, Body Weight
- Being tested
- Restricted dietary protein, Habitual diet
- Medical subject headings
- Body Weight
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Restricted dietary proteinOther
Participants will be allocated to 5 week isocaloric restricted protein intake
Habitual dietOther
Participants will be follow their habitual, high protein intake
| Study group | Role | What they receive |
|---|---|---|
| Restricted dietary protein | Experimental | 5 week intake of a isocaloric diet restricted in protein Receives: Other: Restricted dietary protein; Other: Habitual diet |
| Habitul diet | Experimental | 5 week intake of habitual, high protein diet Receives: Other: Restricted dietary protein; Other: Habitual diet |
What is being measured
The primary outcome is the main question the study is designed to answer.
Body weight
The effect of a prolonged moderate protein-restricted diet on body weight in obese participants.
Measured: 5 weeks
Secondary outcomes (1)
FGF21
study plasma FGF21 concentrations in relation to energy turnover
Measured: 5 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted16 Feb 2024
- Study start1 Oct 2021
- Primary completion31 Dec 2023
- Study completion31 Dec 2023
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Diet, Healthy, Body WeightStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 15 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Copenhagen
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Bente Kiens, D.Sci, Principal investigator, University of Copenhagen
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06263725
- Sponsor's protocol ID
- ALyster
- Acronym
- PR
- Status last verified
- Feb 2024
- First submitted
- 8 Feb 2024
- Last updated
- 16 Feb 2024
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Publications
Lyster AE, Frederiksen AS, Jensen JK, Lundsgaard A, Andersen NR, Jorgensen KS, Weber D, Nachtigall L, Richter EA, Fritzen AM, Kiens B. Dietary Protein Reduction During Isocaloric Conditions Reduces Body Weight in Men With Overweight or Obesity. Obesity (Silver Spring). 2026 Aug;34(8):1569-1582. doi: 10.1002/oby.70248. Epub 2026 Jun 16.
PubMed 42299884
Study at a glance
From the registry record, last updated by the sponsor on 16 Feb 2024. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Protein Restriction (PR) for Weight Loss
- ClinicalTrials.gov ID
- NCT06263725
- Acronym / sponsor ID
- PR / ALyster
- Conditions
- Diet, Healthy, Body Weight
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 15 participants (actual)
- Lead sponsor
- University of CopenhagenUniversity, hospital or other
- Study start
- 1 Oct 2021 (actual)
- Primary completion
- 31 Dec 2023 (actual)
- Study completion
- 31 Dec 2023 (actual)
- First posted
- 16 Feb 2024 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Prolonged dietary protein restriction has been shown to increase energy expenditure in mice simultaneously with an increase in plasma FGF21 levels. In overfeeding studies, a protein-restricted diet reduces weight gain in both mice and humans compared with normal and high-protein diets. Further, in energy balance studies, when lean men are provided with a protein-restricted diet for five weeks, an increase in energy intake was necessary to obtain their body weight. However, whether the effect of a protein-restricted diet is the same when consumed by overweight to obese men has divergent results in both mice and humans.
Detailed description
The present study is a randomised intervention study. Inclusion criteria for the study are healthy males age between 25 and 45 years, BMI between 26 and 32, low physical activity level (low aerobic capacity with a VO2 - peak of 30 ± 10 mL/min/kg), non-smoker, not using snuff, not suffering from diabetes, hypertension, or any daily medication use and a high dietary protein intake (≥1,5 g/kg body weight/day). Before the intervention period, the participants complete a two-week run-in period. The run-in period is designed to collect more detailed information about the participant's habitual diet, body weight, and physical activity pattern, as well as habituate the participants in the various tasks they have to complete during the intervention. Then a five-week intervention period is initiated where the participants are randomized to follow one of the following diets for 5 weeks: 1) a diet reduced in protein, replaced by primary carbohydrates (11 E% Protein, 50 E% carbohydrates, 37 E% fat), and 2) a control diet comprising habitual protein content (21E% Protein, 40 E% carbohydrates, 37 E% fat).
In the five-week intervention period, all food and drinks (besides water and coffee) are provided for the participant. All food is weighed to 1 gram of accuracy in meal portions for a seven-day cycle and is delivered to the participant.
During the intervention the volunteers participate in six test days, one every week during the intervention. 48 hours prior to the weekly test, the participants are asked to abstaine from vigorous physical activity. On all the test days, the participants arrive in the morning in a fasted state (no food or drink after 10 pm the night before) by passive transportation.
On the first test day (WT0), body composition is determined by DXA scan, and the total body water content is measured using bioimpedance analysis. Then resting metabolic rate is measured. Still, in the supine position, a blood sample is obtained from an antecubital vein. Biopsies are taken at baseline and at the end of the intervention (WT5). A fat biopsy is obtained from periumbilical subcutaneous adipose tissue and a muscle biopsy from the vastus lateralis muscle. On test day 3, halfway through the intervention, body composition, body water, and resting metabolic rate are measured, and blood is sampled from an antecubital vein. On week tests 1, 2, and 4, resting metabolic rate is measured, and blood sampled. At all visits to the institute, body weight is also measured.
During the intervention the participants wear a Sens motion sensor to monitor daily activity level.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Restricted dietary protein | Experimental | Other: Restricted dietary protein, Other: Habitual diet5 week intake of a isocaloric diet restricted in protein |
| Habitul diet | Experimental | Other: Restricted dietary protein, Other: Habitual diet5 week intake of habitual, high protein diet |
Who may qualify
- Ages
- 25 to 45 years
- Sex
- Male only
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (1 listed)
- BMI between 26 and 32 Low physical activity level Non-smoker Not using snuff Not suffering from diabetes, hypertension, or any daily medication use High protein intake (≥1,5 g/kg body weight/day)
Key exclusion criteria (1 listed)
- -
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Restricted dietary proteinParticipants will be allocated to 5 week isocaloric restricted protein intake | Other | Habitul diet, Restricted dietary protein |
| Habitual dietParticipants will be follow their habitual, high protein intake | Other | Habitul diet, Restricted dietary protein |
Primary outcome
Body weight
Time frame: 5 weeks
The effect of a prolonged moderate protein-restricted diet on body weight in obese participants.
1 secondary outcome
FGF21
Time frame: 5 weeks
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 16 Feb 2024.
- Derived from this study: PubMed 42299884Lyster AE, Frederiksen AS, Jensen JK, Lundsgaard A, Andersen NR, Jorgensen KS, Weber D, Nachtigall L, Richter EA, Fritzen AM, Kiens B. Dietary Protein Reduction During Isocaloric Conditions Reduces Body Weight in Men With Overweight or Obesity. Obesity (Silver Spring). 2026 Aug;34(8):1569-1582. doi: 10.1002/oby.70248. Epub 2026 Jun 16.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Bente Kiens, D.Sci principal investigator
University of Copenhagen
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Restricted dietary protein and Habitual diet in people with Diet, Healthy, Body Weight, run by University of Copenhagen at 1 site in Denmark.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 1 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 16 Feb 2024. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Denmark. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Body weight (time frame: 5 weeks). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT06263725, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 16 Feb 2024.