Abstract
Obesity is caused by a prolonged positive energy balance1,2. Whether reduced energy expenditure stemming from reduced activity levels contributes is debated3,4. Here we show that in both sexes, total energy expenditure (TEE) adjusted for body composition and age declined since the late 1980s, while adjusted activity energy expenditure increased over time. We use the International Atomic Energy Agency Doubly Labelled Water database on energy expenditure of adults in the United States and Europe (n = 4,799) to explore patterns in total (TEE: n = 4,799), basal (BEE: n = 1,432) and physical activity energy expenditure (n = 1,432) over time. In males, adjusted BEE decreased significantly, but in females this did not reach significance. A larger dataset of basal metabolic rate (equivalent to BEE) measurements of 9,912 adults across 163 studies spanning 100 years replicates the decline in BEE in both sexes. We conclude that increasing obesity in the United States/Europe has probably not been fuelled by reduced physical activity leading to lowered TEE. We identify here a decline in adjusted BEE as a previously unrecognized factor.
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Data availability
With respect to the IAEA database and the meta-analysis of BMR data, this work comprises a secondary analysis of data that are mostly already published and available in the primary literature. These data have been compiled into a database, access to which is free. Forms for requesting data can be found at www.dlwdatabase.org and should be directed to the lead corresponding author j.speakman@abdn.ac.uk or A.J.M.-A. at a.alford@iaea.org. The BMR data are available upon request to co-corresponding author A.K. (a.kurpad@sjri.res.in). The mouse data described in the paper are available upon request to co-corresponding author M.S.R. (matthew.rodeheffer@yale.edu).
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Acknowledgements
The authors gratefully acknowledge funding to directly support this work as well as funding for the original studies that contributed to the database that are not listed individually here. In particular, direct support grants CAS 153E11KYSB20190045 from the Chinese Academy of Sciences to J.R.S. and grant BCS-1824466 from the National Science Foundation of the United States to H.P. are gratefully acknowledged. The mouse work was supported by grants from the Swedish Research Council International Postdoctoral Fellowship (VR 2018-06735) to J.M.A.J., National Institutes of Health grants K01DK109079 and R03DK122189 to M.C.R. and grants R01DK090489 and R01DK126447 to M.S.R. A.K. is supported by the IA/CRC/19/1/610006 grant from the DBT-Wellcome Trust India Alliance. We are grateful to T. Goodrich for comments on earlier drafts of the manuscript. The DLW database, which can be found at https://www.dlwdatabase.org/, is also generously supported by the IAEA, Taiyo Nippon Sanso and SERCON. We are grateful to these companies for their support and especially to T. Oono of Taiyo Nippon Sanso. The funders played no role in the content of this manuscript. Individuals who submitted data to the database that were not used in the analysis in this paper are listed in Supplementary Information (part 3). We are grateful for their contribution to the database.
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J.R.S., K.R.W. and L.G.H. processed and analysed the IAEA data. J.M.A.d.J., J.L.K. and M.C.R. collected, processed and analysed the mouse data. S.S., S.G., J.R.S. and A.K. collected and analysed the retrospective BMR data from the literature. J.R.S., K.R.W., Y.Y., H.S., P.N.A., L.J.A., L.A., K.B.-A., S. Blanc, A.G.B., P.B., S. Brage, M.S.B., N.F.B., S.G.J.A.C., J.A.C., R.C., S.K.D., L.R.D., P.S.W.D., U.E., S.E., T.F., B.W.F., M. Gillingham, A.H.G., M. Gurven, C.H., H.H.H., D.H., S.H., A.M.J., P.K., W.E.K., R.F.K., W.R.L., M.L., A.H.L., C.K.M., E.M., A.C.M., E.P.M., J.C.M., J.P.M., M.L.N., T.A.N., R.M.O., H.P., K.H.P., J.P.-R., G.P., R.L.P., S.B. Racette, D.A.R., E.R., L.M.R., J.R., S.B. Roberts, L.B.S., D.A.S., A.J.S., A.M.S., E.S., S.S.U., G.V., L.M.v.E., E.A.v.M., B.M.W., W.W.W., J.A.Y., T.Y. and X.Z. contributed data to the database. J.R.S, Y.Y., H.S., S.S., A.J.M.-A., C.U., A.H.L., H.P., J.R., D.A.S. and W.W.W. created, curated and administered the database.
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Extended data
Extended Data Fig. 1 Representativeness of the IAEA database dataset included in the analysis.
Distribution of BMI in the sample data for a) females and b) males. Trends in body weight over the interval from 1982 to 2017 for c) males and d) females. There was a significant increase in weight over time in both sexes. For males (gradient = 0.015 kg/month F = 7.04, p = 0.009) reflecting an average weight increase of 5.4 kg over 30 years, and for females (gradient = 0.023 kg/month F 20.84, p = 0.000005) reflecting an average increase of 8.3 kg over 30 years.
Extended Data Fig. 2 Trends over time in unadjusted total, basal and activity energy expenditure in males.
Trends over time in a) unadjusted total energy expenditure, b) unadjusted basal energy expenditure, and c) unadjusted activity energy expenditure for males. All expenditures are in MJ/d and time is expressed in months since January 1982. Significant years are also indicated. Each data point is a different measurement of expenditure. The red lines are the fitted least squares regression fits. For regression details refer to text and Table 1.
Extended Data Fig. 3 Trends over time in unadjusted total, basal and activity energy expenditure in females.
Trends over time in a) unadjusted total energy expenditure, b) unadjusted basal energy expenditure, and c) unadjusted activity energy expenditure for females. All expenditures are in MJ/d and time is expressed in months since January 1982. Significant years are also indicated. Each data point is a different measurement of expenditure. The red lines are the fitted least squares regression fits. For regression details refer to text and Table 1.
Extended Data Fig. 4 Relationships of unadjusted total, basal and activity energy expenditure to body mass index in both males and females.
Relationships between energy expenditure parameters and Body mass index (BMI). In females the relationships were: a) for TEE vs BMI (F = 559.3, p < 10-16), c) BEE vs BMI (F = 242.6, p < 10-16), e) AEE vs BMI (F = 45.13, p < 10-10). For males the relationships were: b) for TEE vs BMI (F = 114.6, p < 10-16), d) BEE vs BMI (F = 79.4, p < 10-16), f) AEE vs BMI (F = 16.28, p = 6 ×10−5).
Extended Data Fig. 5 Trends over time in physical activity level in both males and females.
Trends over time in Physical Activity Level (PAL = TEE/BEE). PAL is dimensionless and time is expressed in months since January 1982. Significant years are also indicated. a) is for males and b) is for females. The red lines are the fitted least squares regression fits. For regression details refer to text.
Extended Data Fig. 6 Search strategy for systematic review.
Systematic review strategy. Flow diagram for selection of studies according to PRISMA guidelines.
Supplementary information
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Materials and methods, Supplementary Tables 1–4 and group authorship details.
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Speakman, J.R., de Jong, J.M.A., Sinha, S. et al. Total daily energy expenditure has declined over the past three decades due to declining basal expenditure, not reduced activity expenditure. Nat Metab 5, 579–588 (2023). https://doi.org/10.1038/s42255-023-00782-2
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DOI: https://doi.org/10.1038/s42255-023-00782-2