Effects of insulin resistance and obesity on lipoproteins and sensitivity to egg feeding.
OBJECTIVE
This study was undertaken to determine if insulin resistance without and with obesity influences LDL response to dietary cholesterol and saturated fat.


RESULTS
We fed 0, 2, and 4 egg yolks per day to 197 healthy subjects in a 4-week, double-blind, randomized, crossover design. Subjects were dichotomized on body mass index (<27.5 and > or =27.5 kg/m2) and insulin sensitivity (insulin-sensitivity index > or =4.2x1.0(-4) and <4.2x1.0(-4) min(-1) microU/mL), yielding insulin-sensitive (IS, n=65), insulin-resistant (IR, n=75), and obese insulin-resistant (OIR, n=58) subjects. Mean fasting baseline LDL cholesterol (LDL-C) levels were higher in IR and OIR subjects (3.44+/-0.67 and 3.32+/-0.80 mol/L) than in IS subjects (2.84+/-0.75 mmol/L) (P<0.001). Progressive triglyceride elevations and HDL-C decreases were seen across the 3 groups. Ingesting 4 eggs daily yielded significant LDL-C increases of 7.8+/-13.7% (IS) and 3.3+/-13.2% (IR) (both P<0.05) compared with 2.4+/-12.6% for OIR (NS). HDL-C increases were 8.8+/-10.4%, 5.2+/-10.4%, and 3.6+/-9.4% in IS, IR, and OIR, respectively (all P<0.01).


CONCLUSIONS
Insulin resistance without and with obesity is associated with elevated LDL-C as well as elevated triglyceride and low HDL-C. The elevated LDL-C cannot be explained by dietary sensitivity, because the LDL-C rise with egg feeding is less in IR persons regardless of obesity status, probably attributable to diminished cholesterol absorption. The results suggest that dietary management of insulin resistance and obesity can focus more on restricting calories and less on restricting dietary fat.
Knopp
Robert H
RH
University of Washington, Northwest Lipid Research Clinic, Seattle, Wash 98104, USA. rhknopp@u.washington.edu
Retzlaff
Barbara
B
Fish
Brian
B
Walden
Carolyn
C
Wallick
Shari
S
Anderson
Melissa
M
Aikawa
Keiko
K
Kahn
Steven E
SE
D000273:Adipose Tissue / Q000000981:diagnostic imaging; D001055:Apolipoproteins B / Q000378:metabolism; D001786:Blood Glucose / Q000378:metabolism; D002791:Cholesterol, Dietary / Q000008:administration & dosage*; D008078:Cholesterol, LDL / Q000378:metabolism*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000378:metabolism*; D010063:Ovum; D012016:Reference Values; D014057:Tomography, X-Ray Computed; D014280:Triglycerides / Q000378:metabolism
D001055:Apolipoproteins B; D001786:Blood Glucose; D002791:Cholesterol, Dietary; D008078:Cholesterol, LDL; D014280:Triglycerides