The effect of repeated episodes of dietary restriction and refeeding on systolic blood pressure and food intake in exercise-trained normotensive rats.
OBJECTIVE
To explore the effects of weight cycling and exercise on blood pressure and macronutrient intake in Sprague-Dawley rats.


METHODS
Female Sprague-Dawley rats (n = 62; 5 months old) were assigned to an ad libitum (Con) or weight-cycled (Cyc) group. They were either sedentary (Con-Sed and Cyc-Sed) or exercise-trained (Con-Ex and Cyc-Ex) on a motorized treadmill (20 m/minute; 60 minutes/day; 6 days/week). The Cyc groups underwent 2 cycles of 3 weeks of 60% food restriction followed by 5 weeks of ad libitum refeeding using a macronutrient self-selection diet. Body mass and food intake were analyzed weekly. Systolic blood pressure (SBP) was measured at baseline and during the first and fifth weeks of each refeeding.


RESULTS
For both cycling periods, SBP was elevated in Cyc vs. Con groups at Week 1 of refeeding, but was similar among groups by Week 5 of refeeding. Both Con groups had greater total energy intake than the Cyc groups for both cycling periods (Cycle 1: 2882.2 +/- 75.1, Con-Sed; 2916.1 +/- 67.1, Con-Ex; 2692.2 +/- 58.7, Cyc-Sed; and 2780.5 +/- 52.4 kcal, Cyc-Ex) (Cycle 2: 2815.8 +/- 75.1, Con-Sed; 2938.8 +/- 49.4, Con-Ex; 2577.1 +/- 60.5, Cyc-Sed; and 2643.5 +/- 65.9 kcal, Cyc-Ex). Relative fat intake (percentage of total kcal/week) was significantly less for Con-Ex and Cyc-Ex than Con-Sed and Cyc-Sed throughout both refeeding periods.


CONCLUSIONS
Weight cycling failed to produce significant sustained effects on SBP, body mass, or food intake. Exercise training, irrespective of diet, lowered dietary fat intake.
Department of Nutrition, University of California at Davis, USA. millergd@wfu.edu
G D
GD
Miller
A G
AG
Dimond
J S
JS
Stern
D000818:Animals; D001794:Blood Pressure; D001835:Body Weight; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D004435:Eating; D002149:Energy Intake; D005260:Female; D005502:Food; D005508:Food Deprivation; D005082:Physical Exertion; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins