title: Is a low leptin concentration, a low resting metabolic rate, or both the expression of the "thrifty genotype"? Results from Mexican Pima Indians.
abstract: BACKGROUND
  The high prevalence of obesity and type 2 diabetes in some populations is believed to be the expression of a "thrifty genotype," which conferred survival advantages during periods of harsh environmental conditions, but has become a liability in industrialized environments of abundance. Low plasma leptin concentrations and a low metabolic rate may be the phenotypic expression of this genotype.
  
  
  OBJECTIVE
  We hypothesized that plasma leptin concentrations and resting metabolic rate would be lower in Mexican Pima Indians not yet exposed to an affluent lifestyle than in non-Pima Mexicans living in the same environment.
  
  
  METHODS
  We studied 208 nondiabetic Pima Indians (105 women and 103 men) living a traditional lifestyle in a remote, mountainous area of northwest Mexico and 183 nondiabetic non-Pima Mexicans (90 women and 93 men) living in the same environment. A subset of 40 (17 women and 23 men) Pima Indians and 40 (19 women and 21 men) non-Pima Mexicans was selected for studies of energy metabolism with a ventilated-hood system.
  
  
  RESULTS
  Leptin concentrations were strongly correlated with percentage body fat in both groups (r = 0.83, P < 0.0001). There was no significant difference in plasma leptin concentration between groups in absolute value (P = 0.90) or after adjustment for percentage body fat, waist circumference, age, and sex (P = 0.40). Similarly, there was no significant difference in resting metabolic rate between groups in absolute value (P = 0.27) or after adjustment for fat-free mass (P = 0.32).
  
  
  CONCLUSIONS
  These results do not support the hypothesis that hypoleptinemia, a relatively low resting metabolic rate, or both are expressions of the thrifty genotype.
authors.affiliation: Phoenix Epidemiology and Clinical Research Branch, AZ, USA.
authors.forename: C S
authors.initials: CS
authors.lastname: Fox
authors.forename: J
authors.initials: J
authors.lastname: Esparza
authors.forename: M
authors.initials: M
authors.lastname: Nicolson
authors.forename: P H
authors.initials: PH
authors.lastname: Bennett
authors.forename: L O
authors.initials: LO
authors.lastname: Schulz
authors.forename: M E
authors.initials: ME
authors.lastname: Valencia
authors.forename: E
authors.initials: E
authors.lastname: Ravussin
mesh_terms: D000328:Adult; D001481:Basal Metabolism / Q000235:genetics*; D001786:Blood Glucose / Q000235:genetics; D002153:Calorimetry, Indirect; D003924:Diabetes Mellitus, Type 2 / Q000208:ethnology / Q000235:genetics; D005260:Female; D005838:Genotype; D006801:Humans; D007198:Indians, North American / Q000235:genetics*; D007328:Insulin / Q000097:blood; D020738:Leptin; D008019:Life Style; D016014:Linear Models; D008297:Male; D008800:Mexico; D008875:Middle Aged; D009765:Obesity / Q000208:ethnology / Q000235:genetics*; D011506:Proteins / Q000032:analysis* / Q000235:genetics
chemical_list: D001786:Blood Glucose; D007328:Insulin; D020738:Leptin; D011506:Proteins