Adult female rats defend "appropriate" energy intake after adaptation to dietary energy.
OBJECTIVE
To determine if adult female rats adapt to lower and higher dietary energy density.


METHODS
Study 1 compared high-fat (56%), high-energy density (HD) (21.6 kJ/g) and high-fat (56%), low-energy density (LD) (16.0 kJ/g) diets before surgery (two groups, 2 weeks, n = 16) and after surgery [ovariectomy (O) Sham (S); 2 x 2 factorial, n = 8; 6 weeks]. The second study (no surgery) compared high-fat (60.0%), high-energy (22.0 kJ/g) and low-fat (10.0%), low-energy (15.1 kJ/g) diets (n = 8).


RESULTS
In study 1, food intake was similar for the first 2 weeks, but rats on the LD diet consumed less energy, gained less weight, and had lower nonfasted serum leptin (all p < 0.0001) than rats on the HD diet. After surgery, rats on the LD and HD diets had similar weight gain, but rats on the LD diet consumed more food (p < 0.0001) and less energy (p < 0.009). O rats consumed more food and gained more weight (p < 0.0001) than S rats. Results from study 2 were similar to those from study 1.


CONCLUSIONS
The results demonstrated that O and S surgery rats and rats with no surgery adjust their food intake to defend a level of energy intake. This defense only occurred after a 2-week adaptation period. The major differences in final body weights and abdominal fat resulted from the initial 2 weeks before adaptation to energy density. Rats fed higher-energy diets seemed to "settle" at a higher level of adiposity, and rats fed lower-energy diets consumed more food to increase energy consumption.
Louisiana Cooperative Extension Service, Baton Rouge, Louisiana, USA.
Heli J
HJ
Roy
Michael J
MJ
Keenan
Erika
E
Zablah-Pimentel
Maren
M
Hegsted
Lisa
L
Bulot
Carol E
CE
O'Neil
L Dwain
LD
Bunting
J Marcos
JM
Fernandez
D000222:Adaptation, Physiological / Q000502:physiology; D000818:Animals; D004040:Dietary Carbohydrates / Q000378:metabolism*; D004041:Dietary Fats / Q000378:metabolism*; D004435:Eating / Q000502:physiology*; D002149:Energy Intake / Q000502:physiology*; D005243:Feces / Q000737:chemistry; D005260:Female; D020738:Leptin / Q000097:blood; D009584:Nitrogen / Q000378:metabolism; D010052:Ovariectomy; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D016482:Urinalysis; D015430:Weight Gain
D004040:Dietary Carbohydrates; D004041:Dietary Fats; D020738:Leptin; D009584:Nitrogen