Metabolic response to a mixed meal in obese and lean women from two South african populations.
OBJECTIVE
Lower lipid and insulin levels are found during a glucose-tolerance test in obese black than obese white South African women. Therefore, beta-cell function and lipid metabolism were compared in these populations during a mixed meal.


METHODS
Blood concentrations of glucose, free fatty acids (FFAs), insulin, lipograms, and in vivo FFA oxidation were determined at fasting and for 7 hours after oral administration of a mixed emulsion containing glucose-casein-sucrose-lipid and [1-(13)C] palmitic acid in 8 lean black women (LBW), 10 obese black women (OBW), 9 lean white women (LWW), and 10 obese white women (OWW). Subcutaneous and visceral fat mass was assessed by computerized tomography.


RESULTS
Visceral fat area was higher in OWW (152.7 +/- 17.0 cm(2)) than OBW (80.0 +/- 6.7 cm(2); p < 0.01). In OBW, 30-minute insulin levels were higher (604.3 +/- 117.6 pM) than OWW (311.0 +/- 42.9 pM; p < 0.05). Total triglyceride was higher in OWW (706.7 +/- 96.0 mM x 7 hours) than OBW (465.7 +/- 48.2 mM x 7 hours; p < 0.05) and correlated with visceral fat area (beta = 0.38, p = 0.05). Palmitate oxidation was higher in lean than obese women in both ethnic groups and correlated negatively with fat mass (beta = -0.58, p < 0.005).


CONCLUSIONS
The higher 30-minute insulin response in OBW may reflect a higher insulinotropic effect of FFAs or glucose. The elevated triglyceride level of OWW may be due to their higher visceral fat mass and possibly reduced clearance by adipose tissue.
Punyadeera
Chamindie
C
Department of Chemical Pathology, National Health Laboratory Service, University of the Witwatersrand Faculty of Health Sciences, Johannesburg, South Africa.
Crowther
Nigel J
NJ
van der Merwe
Maria-Terésa
MT
Toman
Marketa
M
Immelman
Andrew Ronnie
AR
Schlaphoff
Glen P
GP
Gray
Ian Peter
IP
D000273:Adipose Tissue; D044383:Black People; D001786:Blood Glucose / Q000032:analysis; D001823:Body Composition; D001824:Body Constitution; D002247:Carbon Isotopes; D002364:Caseins / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage; D004655:Emulsions; D005215:Fasting; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005502:Food; D005947:Glucose / Q000008:administration & dosage; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood; D008055:Lipids / Q000097:blood; D008875:Middle Aged; D009765:Obesity / Q000378:metabolism*; D010084:Oxidation-Reduction; D019308:Palmitic Acid / Q000008:administration & dosage; D013019:South Africa; D013395:Sucrose / Q000008:administration & dosage; D014057:Tomography, X-Ray Computed; D014280:Triglycerides / Q000097:blood; D014781:Viscera; D044465:White People
D001786:Blood Glucose; D002247:Carbon Isotopes; D002364:Caseins; D004041:Dietary Fats; D004655:Emulsions; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D008055:Lipids; D014280:Triglycerides; D019308:Palmitic Acid; D013395:Sucrose; D005947:Glucose