%0 Journal Article
%T Onset of the Thermic Effect of Feeding (TEF): a randomized cross-over trial
%A Christopher B Scott
%A Jill Fernandes
%A Maya Lehman
%J Journal of the International Society of Sports Nutrition
%D 2007
%I BioMed Central
%R 10.1186/1550-2783-4-24
%X Resting metabolic rate (RMR) and TEF were measured over 30-minute periods via indirect calorimetry using a ventilated hood technique. Eighteen subjects (7 men and 11 women) completed two randomized, double-blind trials. Data were collected in 1-minute measurement intervals. RMR was subtracted from TEF and the time of onset was obtained when two consecutive data points exceeded 5% and 10% of resting metabolic rate.At 5% above RMR the onset of TEF for CHO was 8.4 ¡À 6.2 minutes and was not different as compared to PRO, 8.6 ¡À 5.2 minutes (p = 0.77). Likewise, no differences were found with a 10% increase above RMR: CHO, 14.1 ¡À 7.5 min; PRO, 16.7 ¡À 6.7 min (p = 0.36). Several subjects did not show a 10% increase within 30-min.We conclude that the onset of TEF is variable among subjects but is initiated within about 5 to 20-min for most subjects after ingestion of a 1255 kJ liquid meal. No differences were found between CHO or PRO liquid meals.Antoine Lavosier (1743¨C1794) may have been the first to directly connect digestion with an increased heat production and oxygen consumption [1]. Later in the 20th century it was discovered that increases in energy expenditure after eating, called the thermic effect of feeding (TEF), varied depending on the composition of the meal [2]. Metabolic rate not only rises to a greater extent with an increased caloric intake [3,4] but there is a 6¨C8% increase in energy expenditure with carbohydrate meals, 3% increase with fat, and 25¨C40% with protein based meals [2]. Research tends to focus on the extent and timing of the peak TEF where measurements can go on for hours [5]. Measurement intervals too can be lengthy often occurring in 15 or 30-minute periods. Lengthy measurement intervals reduce measurement variability [6] but they also make it difficult to pinpoint precise time periods; for example, determining when TEF rises.Sports nutritionists have brought timing issues to attention where it has been recommended that nutrient ingestion pos
%U http://www.jissn.com/content/4/1/24