title: Low- and high-carbohydrate diets: body composition differences in rats.
abstract: 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.
authors.affiliation: 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
authors.forename: Ronald L
authors.initials: RL
authors.lastname: McNeel
authors.forename: Harry J
authors.initials: HJ
authors.lastname: Mersmann
mesh_terms: 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
chemical_list: D017931:DNA Primers; D004040:Dietary Carbohydrates; D050556:Fatty Acid-Binding Proteins; D047495:PPAR gamma; D012333:RNA, Messenger; D008071:Lipoprotein Lipase