title: Alterations in energy balance from an exercise intervention with ad libitum food intake.
abstract: Better understanding is needed regarding the effects of exercise alone, without any imposed dietary regimens, as a single tool for body-weight regulation. Thus, we evaluated the effects of an 8-week increase in activity energy expenditure (AEE) on ad libitum energy intake (EI), body mass and composition in healthy participants with baseline physical activity levels (PAL) in line with international recommendations. Forty-six male adults (BMI = 19·7-29·3 kg/m(2)) participated in an intervention group, and ten (BMI = 21·0-28·4 kg/m(2)) in a control group. Anthropometric measures, cardiorespiratory fitness, EI, AEE and exercise intensity were recorded at baseline and during the 1st, 5th and 8th intervention weeks, and movement was recorded throughout. Body composition was measured at the beginning and at the end of the study, and resting energy expenditure was measured after the study. The intervention group increased PAL from 1·74 (se 0·03) to 1·93 (se 0·03) (P < 0·0001) and cardiorespiratory fitness from 41·4 (se 0·9) to 45·7 (se 1·1) ml O2/kg per min (P = 0·001) while decreasing body mass (-1·36 (se 0·2) kg; P = 0·001) through adipose tissue mass loss (ATM) (-1·61 (se 0·2) kg; P = 0·0001) compared with baseline. The control group did not show any significant changes in activity, body mass or ATM. EI was unchanged in both groups. The results indicate that in normal-weight and overweight men, increasing PAL from 1·7 to 1·9 while keeping EI ad libitum over an 8-week period produces a prolonged negative energy balance. Replication using a longer period (and/or more intense increase in PAL) is needed to investigate if and at what body composition the increase in AEE is met by an equivalent increase in EI.
authors.affiliation: Swiss Federal Institute of Sport , Magglingen , Switzerland.
authors.forename: Katarina
authors.initials: K
authors.lastname: Melzer
authors.affiliation: Swiss Federal Institute of Sport , Magglingen , Switzerland.
authors.forename: Anne
authors.initials: A
authors.lastname: Renaud
authors.affiliation: Swiss Federal Institute of Sport, Magglingen, Switzerland; Institute of Human Movement Sciences and Sport, Swiss Federal Institute of Technology, Zurich, Switzerland.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Zurbuchen
authors.affiliation: Institute of Human Movement Sciences and Sport , Swiss Federal Institute of Technology , Zurich , Switzerland.
authors.forename: Céline
authors.initials: C
authors.lastname: Tschopp
authors.affiliation: Faculty of Science , University of Freiburg , Freiburg , Switzerland.
authors.forename: Jan
authors.initials: J
authors.lastname: Lehmann
authors.affiliation: Faculty of Biology and Medicine, Institute of Sports Sciences, University of Lausanne, Lausanne, Switzerland; Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
authors.forename: Davide
authors.initials: D
authors.lastname: Malatesta
authors.affiliation: Swiss Federal Institute of Sport , Magglingen , Switzerland.
authors.forename: Nicole
authors.initials: N
authors.lastname: Ruch
authors.affiliation: Faculty of Biology and Medicine, Department of Physiology, University of Lausanne, Lausanne, Switzerland; Integrative Cardiovascular and Metabolic Physiology, University of Freiburg, Freiburg, Switzerland.
authors.forename: Yves
authors.initials: Y
authors.lastname: Schutz
authors.affiliation: Faculty of Biology and Medicine, Institute of Sports Sciences, University of Lausanne, Lausanne, Switzerland; Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
authors.forename: Bengt
authors.initials: B
authors.lastname: Kayser
authors.affiliation: Swiss Federal Institute of Sport , Magglingen , Switzerland.
authors.forename: Urs
authors.initials: U
authors.lastname: Mäder
keywords: AEE, activity energy expenditure; ATM, adipose tissue mass; Ad libitum food intake; Body composition; EE, energy expenditure; EI, energy intake; Energy balance; Energy expenditure; Exercise intervention; HR, heart rate; LTM, lean tissue mass; MET, metabolic equivalent; PA, physical activity; PAL, physical activity level; REE, resting energy expenditure; TEE, total energy expenditure; VCO2, carbon dioxide production; VO2, oxygen consumption; estVO2max, estimated maximal cardiorespiratory fitness