Low resting and sleeping energy expenditure and fat use do not contribute to obesity in women.
OBJECTIVE
Determine whether sleeping and resting energy expenditure and sleeping, resting, and 24-hour fuel use distinguish obesity-prone from obesity-resistant women and whether these metabolic factors explain long-term weight gain.


METHODS
Forty-nine previously overweight but currently normal-weight women were compared with 49 never-overweight controls. To date, 87% of the 98 women have been re-evaluated after 1 year of follow-up, without intervention, and 38% after 2 years. Subjects were studied at a General Clinical Research Center after 4 weeks of tightly controlled conditions of energy balance and macronutrient intake. Forty-nine obesity-prone weight-reduced women were group-matched with 49 never-overweight obesity-resistant controls. All were premenopausal, sedentary, and normoglycemic. Energy expenditure and fuel use were assessed using chamber calorimetry. Body composition was assessed using DXA.


RESULTS
At baseline, percent body fat was not different between the obesity-prone and control women (33 +/- 4% vs. 32 +/- 5%, respectively; p = 0.22). Analysis of covariance results show that after adjusting for lean and fat mass, sleeping and resting energy expenditure of obesity-prone women was within 2% of controls. Neither sleeping nor resting energy expenditure nor sleeping, resting, or 24-hour fuel use was significantly different between the groups (p > 0.25). None of the metabolic variables contributed significantly to patterns of weight gain at 1 or 2 years of follow-up.


CONCLUSIONS
The results suggest that when resting and sleeping energy expenditure and fuel use are assessed under tightly controlled conditions, these metabolic factors do not distinguish obesity-prone from obesity-resistant women or explain long-term weight changes.
Weinsier
Roland L
RL
Department of Nutrition Sciences, Clinical Nutrition Research Center, University of Alabama at Birmingham, Birmingham, AL 35294-1250, USA.
Hunter
Gary R
GR
Zuckerman
Paul A
PA
Darnell
Betty E
BE
D015502:Absorptiometry, Photon; D000328:Adult; D001481:Basal Metabolism / Q000502:physiology*; D001823:Body Composition; D001835:Body Weight; D002153:Calorimetry, Indirect; D005260:Female; D006801:Humans; D008875:Middle Aged; D009765:Obesity / Q000378:metabolism*; D012146:Rest / Q000502:physiology; D012890:Sleep / Q000502:physiology; D018709:Statistics, Nonparametric; D015431:Weight Loss / Q000502:physiology