The CLOCK Study - A Human Dietary Intervention Study on Peripheral Circadian Clocks and Energy Metabolism (CLOCK)

Interplay of Peripheral Circadian Clocks With Energy Balance and Body Weight Regulation

This human dietary intervention study with a cross-over design aims to investigate the effect of two different diurnal patterns of meal composition on peripheral circadian clocks and energy metabolism in healthy men.

Study Overview

• Status: Completed
• Conditions: Metabolic Response to Dietary Modification
• Intervention / Treatment: Other: Carbohydrate-rich (HC); Other: Fat-rich (HF)

Detailed Description

In this cross-over study, healthy male participants are randomly allocated to one of two study groups: In study group (A) participants consume isocaloric carbohydrate-rich meals (65% Carbohydrates; 20% Fat; 15% Protein) in the morning and fat-rich meals (35% Carbohydrate; 50% Fat; 15% Protein) in the evening for four weeks. After a washout-phase participants consume isocaloric fat-rich meals in the morning and carbohydrate-rich meals in the evening for another four weeks. Study group (B) receives the same interventions in the reversed order.

• Study Type: Interventional
• Enrollment (Actual): 32
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Germany
  • Potsdam, Germany, 14558
    • German Institute of Human Nutrition

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 70 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• BMI between 22 kg/m² and 34,9 kg/m²
• Normal glucose tolerance determined in a 75g-oral glucose tolerance test
• Impaired fasting glucose determined in a 75g-oral glucose tolerance test
• Impaired glucose tolerance determined in a 75g-oral glucose tolerance test

Exclusion Criteria:

• Shift workers or history of shift work
• Men suffering from diseases or conditions that might influence the outcome of the study. Of special interest are diseases that influence body weight regulation (enteropathy, malabsorption, hepatopathy, renal disease, endocrine disorders, diabetes mellitus, eating disorders, heart disease etc.). Also men suffering from coagulopathy, apoplexy and myocardial infarction are excluded from the study.
• Men suffering from psychiatric disease
• Planned changes in physical activity during the study
• Participation in other clinical studies within the last three months
• Weight changes > 2 kg within 2 months prior to screening day
• Men unable to give an informed consent
• Men unable to engage in the dietary interventions
• Men following a special diet

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Other: Carbohydrate-rich_Fat-rich (HC_HF); Isocaloric carbohydrate-rich meals in the morning (06.00 am - 01.30 pm) and isocaloric fat-rich meals in the evening (04.30 pm - 10.00 pm) for 4 weeks	Other: Carbohydrate-rich (HC); 65% Carbohydrate; 20% Fat; 15% Protein; Other: Fat-rich (HF); 35% Carbohydrate; 50% Fat; 15% Protein
Other: Fat-rich_Carbohydrate-rich (HF_HC); Isocaloric fat-rich meals in the morning (06.00 am - 01.30 pm) and isocaloric carbohydrate-rich meals in the evening (04.30 pm - 10.00 pm) for 4 weeks	Other: Carbohydrate-rich (HC); 65% Carbohydrate; 20% Fat; 15% Protein; Other: Fat-rich (HF); 35% Carbohydrate; 50% Fat; 15% Protein

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Dietary-induced changes of glucose and lipid metabolism	week 4
Effect of different diurnal patterns of meal composition on peripheral circadian clocks in blood cells and subcutaneous adipose tissue	week 4

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Dietary-induced changes of satiety and hunger scores	Measured via visual analogue scales	week 4
Effect of different diurnal patterns of meal composition on Lipopolysaccharide-induced cytokine expression		week 4
Dietary-induced changes of the human adipose tissue lipidome		week 4
Integrative analysis of dietary-induced changes of the human adipose tissue transcriptome	Microarray Analysis of adipose tissue samples	week 4

Collaborators and Investigators

• Sponsor: German Institute of Human Nutrition
• Collaborators: Charite University, Berlin, Germany; German Federal Ministry of Education and Research; Heidelberg University; Max-Planck Institute of Molecular Cell Biology and Genetics
• Investigators: Study Director: Andreas FH Pfeiffer, Prof. Dr., German Institute of Human Nutrition

Publications and helpful links

General Publications

• Kessler K, Hornemann S, Petzke KJ, Kemper M, Kramer A, Pfeiffer AF, Pivovarova O, Rudovich N. The effect of diurnal distribution of carbohydrates and fat on glycaemic control in humans: a randomized controlled trial. Sci Rep. 2017 Mar 8;7:44170. doi: 10.1038/srep44170.
• Kessler K, Hornemann S, Petzke KJ, Kemper M, Markova M, Rudovich N, Grune T, Kramer A, Pfeiffer AFH, Pivovarova-Ramich O. Diurnal distribution of carbohydrates and fat affects substrate oxidation and adipokine secretion in humans. Am J Clin Nutr. 2018 Dec 1;108(6):1209-1219. doi: 10.1093/ajcn/nqy224.
• Kessler K, Gerl MJ, Hornemann S, Damm M, Klose C, Petzke KJ, Kemper M, Weber D, Rudovich N, Grune T, Simons K, Kramer A, Pfeiffer AFH, Pivovarova-Ramich O. Shotgun Lipidomics Discovered Diurnal Regulation of Lipid Metabolism Linked to Insulin Sensitivity in Nondiabetic Men. J Clin Endocrinol Metab. 2020 May 1;105(5):dgz176. doi: 10.1210/clinem/dgz176.
• Kessler K, Hornemann S, Rudovich N, Weber D, Grune T, Kramer A, Pfeiffer AFH, Pivovarova-Ramich O. Saliva Samples as A Tool to Study the Effect of Meal Timing on Metabolic And Inflammatory Biomarkers. Nutrients. 2020 Jan 28;12(2):340. doi: 10.3390/nu12020340.

Study record dates

Study Major Dates

• Study Start: January 1, 2014
• Primary Completion (Actual): July 1, 2015
• Study Completion (Actual): August 1, 2015

Study Registration Dates

• First Submitted: May 28, 2015
• First Submitted That Met QC Criteria: June 30, 2015
• First Posted (Estimated): July 1, 2015

Study Record Updates

• Last Update Posted (Estimated): August 26, 2025
• Last Update Submitted That Met QC Criteria: August 20, 2025
• Last Verified: August 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: salmon gonadotropin
• Other Study ID Numbers: DFG grant KFO218 PF164/16-1; DDG021023 (Other Grant/Funding Number: Deutsche Diabetes Gesellschaft)