Changes in energy metabolism in response to 48 h of overfeeding and fasting in Caucasians and Pima Indians.
OBJECTIVE
Differences in the metabolic response to overfeeding and starvation may confer susceptibility or resistance to obesity in humans. To further examine this hypothesis, we assessed the changes in 24 h energy metabolism in response to short-term overfeeding and fasting in Caucasians (C) and Pima Indians (I), a population with a very high propensity for obesity.


METHODS
We measured the changes in 24 h energy expenditure (24 -EE) and 24 h respiratory quotient (24-RQ) in response to 48 h of mixed diet overfeeding (100% above energy requirements) and fasting in a whole body respiratory chamber in 14 male subjects (7 C/7 I, age 30+/-6 y, mean+/-s.d.). Results were compared to a 24 h measurement under eucaloric conditions.


RESULTS
Mean 24-EE increased in response to overfeeding and decreased in response to fasting (all changes P<0.01), with no differences between C (+9.1% and -9.1%) and I (+8.6% and -9.6%). Similarly, mean 24-RQ increased/decreased in response to overfeeding/fasting, respectively (all changes P<0.01), again with no differences between C (+0.06 and -0.05) and I (+0.05 and -0.05). The changes in 24-EE in response to overfeeding and fasting were positively correlated (r=0.70, P<0.01), whereas those in 24-RQ were not (r=0.40, NS).


CONCLUSIONS
Pima Indians do not appear to have an impaired metabolic response to short-term overfeeding and fasting that could explain their propensity for obesity. Individuals with a large increase in energy expenditure in response to overfeeding appear to have a small decrease in energy expenditure in response to starvation (spendthrift phenotype) and vice versa (thrifty phenotype).
Weyer
C
C
Clinical Diabetes and Nutrition Section, NIDDK, National Institutes of Health, Phoenix, Arizona 85016, USA. cweyer@phx.niddk.nih.gov
Vozarova
B
B
Ravussin
E
E
Tataranni
P A
PA
D000328:Adult; D001130:Arizona; D044466:Asian People / Q000235:genetics*; D001481:Basal Metabolism / Q000235:genetics; D004435:Eating / Q000502:physiology*; D004734:Energy Metabolism / Q000235:genetics*; D005215:Fasting / Q000502:physiology; D006801:Humans; D007198:Indians, North American / Q000235:genetics*; D008297:Male; D009765:Obesity / Q000209:etiology* / Q000235:genetics; D010101:Oxygen Consumption / Q000235:genetics; D013997:Time Factors; D044465:White People / Q000235:genetics*