Circadian Rhythms in Resting Metabolic Rate Account for Apparent Daily Rhythms in the Thermic Effect of Food

Leonie Ruddick-Collins* (Corresponding Author), Alan Flanagan, Jonathan D. Johnston, Peter Morgan, Alexandra Johnstone

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Daily variation in the thermic effect of food (TEF) is commonly reported and proposed as a contributing factor to weight gain with late eating. However, underlying circadian variability in resting metabolic rate (RMR) is an overlooked factor when calculating TEF associated with eating at different times of the day.

This work aimed to determine whether methodological approaches to calculating TEF contribute to the reported phenomena of daily variation in TEF.

Fourteen overweight to obese but otherwise healthy individuals had their resting and postprandial energy expenditure (EE) measured over 15.5 hours at a clinical research unit. TEF was calculated for breakfast, lunch, and dinner using standard methods (above a baseline and premeal RMR measure) and compared to a method incorporating a circadian RMR by which RMR was derived from a sinusoid curve model and TEF was calculated over and above the continuously changing RMR. Main outcome measures were TEF at breakfast, lunch, and dinner calculated by different methods.

Standard methods of calculating TEF above a premeal measured RMR showed that morning TEF (60.8 kcal ± 5.6) (mean ± SEM) was 1.6 times greater than TEF at lunch (36.3 kcal ± 8.4) and 2.4 times greater than dinner TEF (25.2 kcal ± 9.6) (P = .022). However, adjusting for modeled circadian RMR nullified any differences between breakfast (54.1 kcal ± 30.8), lunch (49.5 kcal ± 29.4), and dinner (49.1 kcal ± 25.7) (P = .680).

Differences in TEF between morning and evening can be explained by the underlying circadian resting EE, which is independent of an acute effect of eating.
Original languageEnglish
Pages (from-to) e708–e715
Number of pages8
JournalJournal of Clinical Endocrinology and Metabolism
Issue number2
Early online date2 Sept 2021
Publication statusPublished - 1 Feb 2022

Bibliographical note

We would like to thank Barbara Fielding, Adam Collins, Hayriye Biyikoglu, Alice Brealy, and Paul Jefcoate as well as all the staff at the Surrey Clinical Research Facility for their assistance in running this study. We would also like to thank Graham Horgan from Biomathematics and Statistics Scotland, for input
on the modeling and statistical analysis. Financial Support: This study was funded by the Medical Research Council (grant No. MR/P012205/1, The Big Breakfast
Study). A.M.J. and P.J.M. acknowledge funding support from the Scottish Government, Rural and Environment Science and Analytical Services Division.

Data Availability Statement

Some or all data sets generated during and/or analyzed during the present study are not publicly available but are available from the corresponding author on reasonable request. Restrictions apply to the availability of some or all data generated or analyzed during this study to preserve patient confidentiality or because they were used under license. The corresponding author will on request detail the restrictions and any conditions under which access to some data may be provided.


  • chrononutrition
  • diet-induced thermogenesis
  • diurnal
  • breakfast
  • energy balance
  • energy expenditure


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