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Completed

NCT Number: NCT06267235

Dietary Protein Restriction and Health

The incidence of type 2 diabetes worldwide has increased significantly over the past decades, which is associated with changing dietary habits and physical inactivity. According to the diet, so far there has been a great focus on the quality of carbohydrates and fat in relation to metabolic health, while the importance of protein has been neglected. The Danes' average protein intake is 1.5 g/kg/day, which is at the high end of the recommendations (0.8-1.5 g/kg/day) from the Nordic Nutrition Recommendations (NNR 2023). Recent studies in rodents have shown that protein restriction has positive effects on health, including improved glucose and insulin homeostasis and reduced fat mass, while a high intake of protein has a negative effect on insulin sensitivity. Previously the investigators have shown, in healthy young men, that consuming a diet low in protein (0.9 g/kg/day), compared to the participants usual diet (1.5 g/kg/day), over 7 days, resulted in an increased insulin sensitivity as well as a marked increase in the plasma fibroblast growth factor 21 (FGF21) concentration. The increased insulin sensitivity is thought to be mediated by the increase in plasma FGF21 concentration. However, the effect is not yet fully understood. It is also not clear whether the increase in plasma FGF21 concentration, as well as the mentioned metabolic effects on insulin and glucose homeostasis, will take place if the participants are kept weight stable on a eucaloric diet.

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Key information

Conditions

Protein Diet Healthy

Age range

25 year–35 year

Sex eligibility

Male

Study type

Interventional

Phase

Not applicable

Primary location

University of Copenhagen

Copenhagen, 2100, Denmark

About this study

A three-arm protocol was performed. In protocol 1, participants ingested either a low-protein (LP) meal or a higher protein (HP) meal in a randomized order, separated by 72 h, followed by a 5-week low-protein, high-carbohydrate (LPHC) diet. In protocol 2 and 3, participants ingested either a LPHC diet or a low-protein, high-fat (LPHF) diet for 5 weeks followed by a higher protein diet (HPD) for another 5 weeks. All diets were eucaloric. Resting metabolic rate (RMR) was measured pre, during and post the protein-restricted interventions. A hyperinsulimic-euglycemic clamp was performed post the protein-restricted interventions and post the HPD interventions. A basal subcutaneous abdominal fat biopsy was obtained post the protein-restricted interventions and post the HPD interventions. In a run-in period over 14 days, the participant records the daily number of steps and physical activity, in order to determine their habitual activity level. During this period, a 4-day dietary record is performed, where all ingested food was weighed and recorded. During the experimental period the participant followed the supplied diet. All food consumed during the interventions was handed out to the subject at the institute. All food was packaged and weighed to 1 gram of accuracy. During the dietary intervention, a weekly test in the morning was performed, where the resting metabolic rate was measured and blood samples taken from the arm vein. At week 0, 5 and week 10 body composition was measured by dual energy x-ray absorptiometry scanning (DXA), and the fat biopsy was obtained . At all tests participants arrived fasting at the institute at 8:00 a.m. in the morning. The participant arrived by car or public transport.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • BMI≤25
  • Maximal oxygen uptake ≤42-51 ml/kg/min) • non-smoking

Exclusion criteria

  • The use of medicine

Treatment and study plan

Dietary protein restriction

Other

The consumption of different diets restricted in protein replaced by either carbohydrate or fat and an habitual diet.

Primary outcomes

  1. Energy balance

    Time frame: from week 0 to week 10.

    Energy balance was measured in an over-night fasted state via indirect calorimetry expressed in MJ/day

    prolonged eucaloric dietary protein restriction compared with a higher habitual protein intake

  2. Insulin sensitivity

    Time frame: Measured at week 5 (low protein, high carbohydrate diet) and week 5 on habitual diet and at week 5 (low protein high fat diet) and week 5 on habitual diet

    Insulin sensitivity was measured by the hyperinsulinemic, euglycemic clamp procedure

Secondary outcomes

  1. Adipose tissue proteomics

    Time frame: After 5 weeks low protein, high carbohydrate and 5 weeks low protein, high fat. On the tenth week on habitual diet

    Mass spectroscopy

  2. Plasma FGF21

    Time frame: Every week from week 0 to week 10

    Measured by Elisa

Sponsors and collaborators

Lead sponsor

University of Copenhagen

Other

Registry information

Official study title

Dietary Protein, FGF21 and Glucose Homeostasis

Acronym: LOWPRO

Important dates

Study start
2018
Primary completion
2020
Study completion
2024
First posted
Feb 20, 2024
Registry last updated
May 7, 2024

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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