title: Energy expenditure and activity among Hadza hunter-gatherers.
abstract: OBJECTIVE
  Studies of total energy expenditure, (TEE; kcal/day) among traditional populations have challenged current models relating habitual physical activity to daily energy requirements. Here, we examine the relationship between physical activity and TEE among traditional Hadza hunter-gatherers living in northern Tanzania.
  
  
  METHODS
  Hadza adults were studied at two camps, with minimal intervention so as to monitor energy expenditure and activity during normal daily life. We measured daily walking distance and walking speed using wearable GPS units for 41 adults. For a subset of 30 adults, we measured TEE using doubly labeled water, three indices of work load (foraging return rate, maternal status, and number of dependent children), and urinary biomarkers of metabolic activity and stress (8-hydroxydeoxyguanosine, cortisol, and testosterone).
  
  
  RESULTS
  Fat-free mass was the single strongest predictor of TEE among Hadza adults (r(2)  = 0.66, P < 0.001). Hadza men used greater daily walking distances and faster walking speeds compared with that of Hadza women, but neither sex nor any measure of physical activity or work load were correlated with TEE in analyses controlling for fat-free mass. Compared with developed, industrial populations, Hadza adults had similar TEE but elevated levels of metabolic stress as measured by 8-hydroxydeoxyguanosine.
  
  
  CONCLUSIONS
  Our results indicate that daily physical activity may not predict TEE within traditional hunter-gatherer populations like the Hadza. Instead, adults with high levels of habitual physical activity may adapt by reducing energy allocation to other physiological activity.
authors.affiliation: Department of Anthropology, Hunter College, City University of New York, New York City, New York.|New York Consortium for Evolutionary Primatology, New York City, New York.
authors.forename: Herman
authors.initials: H
authors.lastname: Pontzer
authors.affiliation: School of Anthropology, University of Arizona, Tucson, Arizona.
authors.forename: David A
authors.initials: DA
authors.lastname: Raichlen
authors.affiliation: Department of Anthropology, Yale University, New Haven, Connecticut.
authors.forename: Brian M
authors.initials: BM
authors.lastname: Wood
authors.affiliation: Department of Anthropology, University of New Mexico, Albuquerque, New Mexico.
authors.forename: Melissa
authors.initials: M
authors.lastname: Emery Thompson
authors.affiliation: Program in Physical Therapy and Department of Medicine, School of Medicine, Washington University in St. Louis, St. Louis, Missouri.
authors.forename: Susan B
authors.initials: SB
authors.lastname: Racette
authors.affiliation: National Museums of Tanzania, Dar es Salaam, Tanzania.
authors.forename: Audax Z P
authors.initials: AZ
authors.lastname: Mabulla
authors.affiliation: Department of Anthropology, Cambridge University, Cambridge, United Kingdom.
authors.forename: Frank W
authors.initials: FW
authors.lastname: Marlowe
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000652:urine; D001835:Body Weight; D004734:Energy Metabolism; D005191:Family Characteristics; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D009043:Motor Activity; D012737:Sex Factors; D013636:Tanzania; D016526:Workload; D055815:Young Adult
chemical_list: D015415:Biomarkers