Diurnal influences of fasted and non-fasted brisk walking on gastric emptying rate, metabolic responses, and appetite in healthy males

McIver, Victoria J, Mattin, Lewis R, Evans, Gethin H and Yau, Adora MW (2019) Diurnal influences of fasted and non-fasted brisk walking on gastric emptying rate, metabolic responses, and appetite in healthy males. Appetite, 143. p. 104411. ISSN 0195-6663

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Abstract

Growing evidence suggests circadian rhythms, nutrition and metabolism are intimately linked. Intermittentfasting (IMF) has become an increasingly popular intervention for metabolic health and combining IMF withexercise may lead to benefits for weight management. However, little is known about the diurnal variation offasted exercise. This study aimed to investigate the diurnal influences on gastric emptying rate (GER), metabolicresponses, and appetite to fasted and non-fasted exercise. Twelve healthy males completed four 45 min walks ina randomised order. Walks were completed in the morning (AM) and evening (PM) and either fasted (FASTED)or after consumption of a standardised meal (FED). GER of a semi-solid lunch was subsequently measured for 2 husing the13C breath test. Blood glucose concentration, substrate utilisation, and ratings of appetite were mea-sured throughout. Energy intake was also assessed for the following 24 h. GER Tlagwas slower in PM-FASTEDcompared to AM-FASTED, AM-FED, and PM-FED (75 ± 18 min vs. 63 ± 14 min,P= 0.001, vs. 65 ± 10 min,P= 0.028 and vs. 67 ± 16 min,P= 0.007). Blood glucose concentration was greater in the FED trials incomparison to the FASTED trials pre-lunch (P< 0.05). Fat oxidation was greater throughout exercise in bothFASTED trials compared to FED, and remained higher in FASTED trials than fed trials post-exercise until 30 minpost-lunch ingestion (allP< 0.05). No differences were found for appetite post-lunch (P> 0.05) or 24 h post-energy intake (P= 0.476). Thesefindings suggest that evening fasted exercise results in delayed GER, withoutchanges in appetite. No compensatory effects were observed for appetite, and 24 h post-energy intake for bothfasted exercise trials, therefore, increased fat oxidation holds positive implications for weight management.