a1 Brain, Performance and Nutrition Research Centre, School of Life Sciences, Northumbria University, Northumberland Building, Newcastle upon Tyne NE1 8ST, UK
a2 Department of Sport and Exercise Sciences, School of Life Sciences, Northumbria University, Northumberland Building, Newcastle upon Tyne NE1 8ST, UK
The present study examined the impact of breakfast and exercise on postprandial metabolism, appetite and macronutrient balance. A sample of twelve (blood variables n 11) physically active males completed four trials in a randomised, crossover design comprising a continued overnight fast followed by: (1) rest without breakfast (FR); (2) exercise without breakfast (FE); (3) breakfast consumption (1859 kJ) followed by rest (BR); (4) breakfast consumption followed by exercise (BE). Exercise was continuous, moderate-intensity running (expending approximately 2·9 MJ of energy). The equivalent time was spent sitting during resting trials. A test drink (1500 kJ) was ingested on all trials followed 90 min later by an ad libitum lunch. The difference between the BR and FR trials in blood glucose time-averaged AUC following test drink consumption approached significance (BR: 4·33 (sem 0·14) v. FR: 4·75 (sem 0·16) mmol/l; P= 0·08); but it was not different between FR and FE (FE: 4·77 (sem 0·14) mmol/l; P= 0·65); and was greater in BE (BE: 4·97 (sem 0·13) mmol/l) v. BR (P= 0·012). Appetite following the test drink was reduced in BR v. FR (P= 0·006) and in BE v. FE (P= 0·029). Following lunch, the most positive energy balance was observed in BR and least positive in FE. Regardless of breakfast, acute exercise produced a less positive energy balance following ad libitum lunch consumption. Energy and fat balance is further reduced with breakfast omission. Breakfast improved the overall appetite responses to foods consumed later in the day, but abrogated the appetite-suppressive effect of exercise.
(Received July 30 2012)
(Revised October 04 2012)
(Accepted November 14 2012)
(Online publication January 23 2013)
Abbreviations: AUCINS/GLU, serum insulin AUC to blood glucose AUC ratio; BE, overnight fast followed by breakfast and exercise; BR, overnight fast followed by breakfast and rest; FE, overnight fast followed by exercise without breakfast; FR, overnight fast followed by rest without breakfast; GLP-1, glucagon-like peptide 1; ISIMatsuda, Matsuda insulin sensitivity index; VAS, visual analogue scale