A randomized controlled trial to isolate the effects of fasting and energy restriction on weight loss and metabolic health in lean adults

Templeman, Iain; Smith, Harry Alex; Chowdhury, Enhad; Chen, Yung Chih; Carroll, Harriet; Johnson-Bonson, Drusus; Hengist, Aaron; Smith, Rowan; Creighton, Jade; Clayton, David; Varley, Ian; Karagounis, Leonidas Georgios; Wilhelmsen, Andrew; Tsintzas, Kostas; Reeves, Sue; Walhin, Jean Philippe; Gonzalez, Javier Thomas; Thompson, Dylan; Betts, James Alexander

Abstract

Intermittent fasting may impart metabolic benefits independent of energy balance by initiating fasting-mediated mechanisms. This randomized controlled trial examined 24-hour fasting with 150% energy intake on alternate days for 3 weeks in lean, healthy individuals (0:150; n = 12). Control groups involved a matched degree of energy restriction applied continuously without fasting (75% energy intake daily; 75:75; n = 12) or a matched pattern of fasting without net energy restriction (200% energy intake on alternate days; 0:200; n = 12). Primary outcomes were body composition, components of energy balance, and postprandial metabolism. Daily energy restriction (75:75) reduced body mass (-1.91 ± 0.99 kilograms) almost entirely due to fat loss (-1.75 ± 0.79 kilograms). Restricting energy intake via fasting (0:150) also decreased body mass (-1.60 ± 1.06 kilograms; P = 0.46 versus 75:75) but with attenuated reductions in body fat (-0.74 ± 1.32 kilograms; P = 0.01 versus 75:75), whereas fasting without energy restriction (0:200) did not significantly reduce either body mass (-0.52 ± 1.09 kilograms; P ≤ 0.04 versus 75:75 and 0:150) or fat mass (-0.12 ± 0.68 kilograms; P ≤ 0.05 versus 75:75 and 0:150). Postprandial indices of cardiometabolic health and gut hormones, along with the expression of key genes in subcutaneous adipose tissue, were not statistically different between groups (P > 0.05). Alternate-day fasting less effectively reduces body fat mass than a matched degree of daily energy restriction and without evidence of fasting-specific effects on metabolic regulation or cardiovascular health.

• Journal Article Type: Article
• Acceptance Date: May 10, 2021
• Publication Date: Jun 16, 2021
• Deposit Date: Oct 28, 2021
• Publicly Available Date: Oct 28, 2021
• Journal: Science Translational Medicine
• Print ISSN: 1946-6234
• Electronic ISSN: 1946-6242
• Peer Reviewed: Peer Reviewed
• Volume: 13
• Issue: 598
• Article Number: 00
• DOI: https://doi.org/10.1126/scitranslmed.abd8034
• Public URL: https://nottingham-repository.worktribe.com/output/5752663
• Publisher URL: https://www.science.org/doi/abs/10.1126/scitranslmed.abd8034
• Additional Information: This is the author’s version of the work. It is posted here by permission of the AAAS for personal use, not for redistribution. The definitive version was published in Science Translational Medicine on ; 16.6.21, Volume 13 DOI: https://www.science.org/doi/abs/10.1126/scitranslmed.abd8034