{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,28]],"date-time":"2026-07-28T05:00:16Z","timestamp":1785214816739,"version":"3.55.0"},"reference-count":34,"publisher":"Wiley","issue":"12","license":[{"start":{"date-parts":[[2026,6,19]],"date-time":"2026-06-19T00:00:00Z","timestamp":1781827200000},"content-version":"vor","delay-in-days":18,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,6,1]],"date-time":"2026-06-01T00:00:00Z","timestamp":1780272000000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["physoc.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Physiological Reports"],"published-print":{"date-parts":[[2026,6]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>\n                    Metabolic flexibility (MetaFlex) reflects the ability to adjust substrate oxidation to changes in fuel availability and energy demand. How MetaFlex should be assessed under physiologically relevant metabolic challenges remains unclear. Data from two studies were analyzed in adults with contrasting adiposity and training status, known to influence MetaFlex: healthy lean inactive or trained adults (Ln\u2010inactive\/Ln\u2010trained, BMI: 19\u201325\u2009kg\/m\n                    <jats:sup>2<\/jats:sup>\n                    ), inactive adults with obesity (Ob\u2010Inactive, BMI: 30\u201340\u2009kg\/m\n                    <jats:sup>2<\/jats:sup>\n                    ), and weight\u2010reduced inactive or trained (RO\u2010inactive\/RO\u2010trained, BMI: 25\u201040\u2009kg\/m\n                    <jats:sup>2<\/jats:sup>\n                    , &gt;10% weight loss). Participants completed 24\u2010h stays in a whole\u2010room calorimeter under a low\u2010fat (20% fat, LF\u2010EB), high\u2010fat (50% fat, HF\u2010EB) diet, or acute moderate\u2010intensity exercise (EX\u2010EB) in energy balance, or resting in energy balance (REST\u2010EB), or acute exercise inducing 15% energy deficit (EX\u2010ED). MetaFlex was assessed using day\u2010night respiratory quotient (\u0394RQ\n                    <jats:sub>day\u2010night<\/jats:sub>\n                    ), nighttime RQ (RQ\n                    <jats:sub>sleep<\/jats:sub>\n                    ) and 24\u2010h variances of RQ and insulin. Linear mixed models were used. Compared with LF\u2010EB, HF\u2010EB increased \u0394RQ (Difference LSMeans\u2009\u00b1\u2009SE, 0.040\u2009\u00b1\u20090.016,\n                    <jats:italic>p<\/jats:italic>\n                    \u2009=\u20090.02) and 24\u2010h RQ variance (0.895\u2009\u00b1\u20090.345,\n                    <jats:italic>p<\/jats:italic>\n                    \u2009=\u20090.02) and reduced 24\u2010h insulin variance (0.65\u2009\u00b1\u20090.13,\n                    <jats:italic>p<\/jats:italic>\n                    \u2009&lt;\u20090.001) across groups. EX\u2010EB did not modify any MetaFlex index. During EX\u2010ED, 24\u2010h insulin variance differed by group, with higher values in Ob\u2010Inactive compared with Ln\u2010Inactive, RO\u2010Trained, and RO\u2010Inactive (\n                    <jats:italic>p<\/jats:italic>\n                    \u2009&lt;\u20090.022 for all). MetaFlex is challenge\u2010dependent. When EB is maintained, short\u2010term high\u2010fat feeding is more effective than acute exercise for probing MetaFlex. Exercise combined with an energy deficit reveals between\u2010group differences driven primarily by insulin dynamics. Individuals with obesity display reduced MetaFlex, whereas weight loss\u2014especially when combined with training\u2014partially restores MetaFlex.\n                  <\/jats:p>","DOI":"10.14814\/phy2.70979","type":"journal-article","created":{"date-parts":[[2026,6,20]],"date-time":"2026-06-20T04:15:27Z","timestamp":1781928927000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Assessing metabolic flexibility in adults under physiological conditions: Effects of dietary fat and exercise in whole\u2010room calorimetry"],"prefix":"10.14814","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0071-1190","authenticated-orcid":false,"given":"Carmen P.","family":"Ortega\u2010Santos","sequence":"first","affiliation":[{"name":"Exercise and Nutrition Sciences, Milken Institute School of Public Health The George Washington University  Washington DC USA"},{"name":"Division of Endocrinology, Metabolism, and Diabetes, Department of Medicine, Anschutz Health and Wellness Center University of Colorado\u2010Anschutz Medical Campus  Aurora Colorado USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Edward L.","family":"Melanson","sequence":"additional","affiliation":[{"name":"Division of Endocrinology, Metabolism, and Diabetes, Department of Medicine, Anschutz Health and Wellness Center University of Colorado\u2010Anschutz Medical Campus  Aurora Colorado USA"},{"name":"Division of Geriatric Medicine, Department of Medicine University of Colorado Anschutz Medical Campus  Aurora Colorado USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Daniel H.","family":"Bessesen","sequence":"additional","affiliation":[{"name":"Division of Endocrinology, Metabolism, and Diabetes, Department of Medicine, Anschutz Health and Wellness Center University of Colorado\u2010Anschutz Medical Campus  Aurora Colorado USA"},{"name":"Denver Health Medical Center  Denver Colorado USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Pan","family":"Zhaoxing","sequence":"additional","affiliation":[{"name":"Department of Biostatistics University of Colorado School of Medicine  Aurora Colorado USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Corey A.","family":"Rynders","sequence":"additional","affiliation":[{"name":"Division of Geriatric Medicine, Department of Medicine University of Colorado Anschutz Medical Campus  Aurora Colorado USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1266-5144","authenticated-orcid":false,"given":"Audrey","family":"Bergouignan","sequence":"additional","affiliation":[{"name":"Division of Endocrinology, Metabolism, and Diabetes, Department of Medicine, Anschutz Health and Wellness Center University of Colorado\u2010Anschutz Medical Campus  Aurora Colorado USA"},{"name":"Institut Pluridisciplinaire Hubert Curien Universit\u00e9 de Strasbourg, CNRS Strasbourg  Strasbourg France"},{"name":"UMR 7178 Centre National de la Recherche Scientifique (CNRS)  Strasbourg France"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,6,19]]},"reference":[{"key":"e_1_2_13_2_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.pcad.2013.09.002"},{"key":"e_1_2_13_3_1","doi-asserted-by":"publisher","DOI":"10.1159\/000517589"},{"key":"e_1_2_13_4_1","doi-asserted-by":"publisher","DOI":"10.1152\/JAPPLPHYSIOL.00576.2019"},{"key":"e_1_2_13_5_1","doi-asserted-by":"publisher","DOI":"10.2337\/db19\u20100719"},{"key":"e_1_2_13_6_1","doi-asserted-by":"publisher","DOI":"10.1371\/JOURNAL.PONE.0030164"},{"key":"e_1_2_13_7_1","doi-asserted-by":"publisher","DOI":"10.1371\/JOURNAL.PONE.0094181"},{"key":"e_1_2_13_8_1","doi-asserted-by":"publisher","DOI":"10.1152\/japplphysiol.00698.2011"},{"key":"e_1_2_13_9_1","doi-asserted-by":"publisher","DOI":"10.1007\/s00125\u2010021\u201005535\u2010y"},{"key":"e_1_2_13_10_1","doi-asserted-by":"publisher","DOI":"10.14814\/phy2.14916"},{"key":"e_1_2_13_11_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.clnesp.2016.05.003"},{"key":"e_1_2_13_12_1","doi-asserted-by":"publisher","DOI":"10.1249\/MSS.0b013e31823f679f"},{"key":"e_1_2_13_13_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.clnu.2019.12.010"},{"key":"e_1_2_13_14_1","doi-asserted-by":"publisher","DOI":"10.1111\/OBR.13131"},{"key":"e_1_2_13_15_1","doi-asserted-by":"publisher","DOI":"10.2337\/db08\u20100043"},{"key":"e_1_2_13_16_1","doi-asserted-by":"publisher","DOI":"10.1152\/ajpendo.90558.2008"},{"key":"e_1_2_13_17_1","doi-asserted-by":"publisher","DOI":"10.3390\/nu13072230"},{"key":"e_1_2_13_18_1","doi-asserted-by":"publisher","DOI":"10.2337\/diabetes.52.9.2191"},{"key":"e_1_2_13_19_1","doi-asserted-by":"publisher","DOI":"10.1146\/annurev.nutr.7.1.187"},{"key":"e_1_2_13_20_1","doi-asserted-by":"publisher","DOI":"10.1038\/s41366\u2010020\u20100591\u2010x"},{"key":"e_1_2_13_21_1","doi-asserted-by":"publisher","DOI":"10.1096\/fj.14\u2010269852"},{"key":"e_1_2_13_22_1","doi-asserted-by":"publisher","DOI":"10.1152\/ajpendo.1999.277.6.e1130"},{"key":"e_1_2_13_23_1","doi-asserted-by":"publisher","DOI":"10.2337\/diabetes.49.5.677"},{"key":"e_1_2_13_24_1","doi-asserted-by":"publisher","DOI":"10.1002\/oby.23450"},{"key":"e_1_2_13_25_1","doi-asserted-by":"publisher","DOI":"10.1002\/oby.22982"},{"key":"e_1_2_13_26_1","doi-asserted-by":"publisher","DOI":"10.1002\/oby.24245"},{"key":"e_1_2_13_27_1","doi-asserted-by":"publisher","DOI":"10.1152\/JAPPLPHYSIOL.00958.2009"},{"key":"e_1_2_13_28_1","doi-asserted-by":"publisher","DOI":"10.3390\/ijerph191912913"},{"key":"e_1_2_13_29_1","doi-asserted-by":"publisher","DOI":"10.3390\/nu13124245"},{"key":"e_1_2_13_30_1","doi-asserted-by":"publisher","DOI":"10.1038\/oby.2007.572"},{"key":"e_1_2_13_31_1","doi-asserted-by":"publisher","DOI":"10.1002\/oby.20609"},{"key":"e_1_2_13_32_1","doi-asserted-by":"publisher","DOI":"10.1210\/jc.2017\u201002267"},{"key":"e_1_2_13_33_1","doi-asserted-by":"publisher","DOI":"10.1113\/JP273282"},{"key":"e_1_2_13_34_1","doi-asserted-by":"publisher","DOI":"10.1519\/JSC.0000000000004316"},{"key":"e_1_2_13_35_1","doi-asserted-by":"publisher","DOI":"10.1038\/s41598\u2010021\u201097301\u20108"}],"container-title":["Physiological 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