Extended morning fasting, energy balance and human health

Abstract

Cross-sectional evidence associates breakfast omission with negative health outcomes. The present work aimed to examine if these cross-sectional associations have a causal component, by conducting randomised control trials in healthy humans. It was established using lean individuals that there are divergent hormonal responses to morning feeding and fasting, although increased energy intake at lunch following fasting incompletely compensated for breakfast intake. Hormonal and subjective appetite responses in the afternoon did not consistently provide evidence for increased hunger following fasting. In the same participants assigned to a 6-week free-living intervention of either 700 kcal pre 11:00 or fasting until 12:00 daily, it was found that energy intake was greater in those assigned breakfast consumption, but that physical activity was also greater than those fasting. Cardiovascular risk factors and measures of metabolic control were largely unaffected by either intervention. There was no adaptation of acute metabolic/hormonal responses to feeding following either intervention. In obese individuals, similar patterns of results were obtained for the hormonal and metabolic responses to acute feeding and fasting, but with no compensation for breakfast intake at lunch. Results from the free-living intervention demonstrated no difference in energy intake between groups or physical activity over the entire day, but greater energy expenditure during the morning in those consuming breakfast. Markers of cardiovascular health and metabolic control were generally not differently affected by either intervention. Neither intervention caused adaptation of the acute hormonal and metabolic responses to feeding. In summary, acute morning fasting does not cause complete compensation for breakfast intake at lunch, or result in greater hunger throughout the afternoon. Daily morning fasting does not affect acute responses to feeding or cause increased energy intake or weight gain relative to self-selected breakfast consumption, but seems to limit physical activity in lean, and to a lesser extent, in obese individuals.

Date of Award	22 Oct 2014
Original language	English
Awarding Institution	University of Bath
Sponsors	Biotechnology and Biological Sciences Research Council
Supervisor	James Betts (Supervisor) & Dylan Thompson (Supervisor)