Low- and high-carbohydrate diets: body composition differences in rats.
OBJECTIVE
To determine differences in adipose tissue mass, cell size, and lipid metabolism transcripts and differences in composition of body weight loss and energy expenditure (EE) after isoenergetic, energy-restricted intake of low-carbohydrate/high-fat/high-protein (LC) and high-carbohydrate/low-fat/moderate-protein (HC) diets.


METHODS
Ten-week old female Sprague-Dawley rats were fed a high-fat diet ad libitum for 8 weeks to induce weight gain and fat deposition. Weight-matched rats were then assigned to isoenergetic LC (Atkins) and HC (American Dietary Association Exchange) diets for 10 weeks at 65% of ad libitum energy intake.


RESULTS
There was no significant difference in the serum lipid profiles or amount of body weight lost between the HC and LC groups, whereas a higher insulin sensitivity index (p < 0.01) resulted from the HC compared with the LC diet. Compared with the post-restriction LC group, the HC group demonstrated (p < 0.05) higher EE during active hours, lower mRNA levels for the lipogenic genes peroxisome proliferator-activated receptor gamma2, lipoprotein lipase, and, adipocyte fatty acid binding protein, decreased adipocyte cell volume, and decreased fat mass.


CONCLUSIONS
Results indicated down-regulation of lipogenic genes, decreased fat mass, and, therefore, improved body composition in the post-restriction HC compared with the LC group. The small mean differences between the two diet groups (p = 0.11) in 24-hour EE over the 10 weeks of diet intervention would account for the majority of the lower mean body weights in the post-restriction HC group. These data suggest that macronutrient composition of the diet influences body composition and indicate a distinction between HC and LC diets.
McNeel
Ronald L
RL
U.S. Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030, USA. rmcneel@bcm.tmc.edu
Mersmann
Harry J
HJ
D000818:Animals; D001483:Base Sequence; D001823:Body Composition; D001835:Body Weight; D017931:DNA Primers; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004734:Energy Metabolism; D050556:Fatty Acid-Binding Proteins / Q000235:genetics; D005260:Female; D007333:Insulin Resistance; D008071:Lipoprotein Lipase / Q000235:genetics; D047495:PPAR gamma / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction
D017931:DNA Primers; D004040:Dietary Carbohydrates; D050556:Fatty Acid-Binding Proteins; D047495:PPAR gamma; D012333:RNA, Messenger; D008071:Lipoprotein Lipase