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 p ressure aid macronutrient intake in Sprague-Dawley rats. Research Methods a nd Procedures: Female Sprague-Dawley rats (n = 62; 5 months old) were assig ned to an ad libitum (Con) or weight-cycled (Cyc) group. They were either s edentary (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 gr oups underwent 2 cycles of 3 weeks of 60% food restriction followed by 5 we eks of ad libitum refeeding using a macronutrient self-selection diet. Body mass and food intake were analyzed weekly. Systolic blood pressure (SBP) w as measured at baseline and during the first and fifth weeks of each refeed ing. Results: For both cycling periods, SEP was elevated in Cyc vs. Con gro ups at Week 1 of refeeding, but was similar among groups by Week 5 of refee ding. Both Con groups had greater total energy intake than the Cyc groups f or 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) (Cycl e 2: 2815.8 +/- 75.1, Con-Sed; 2938.8 +/- 49.4, Con-Ex; 2577.1 +/- 60.5, Cy c-Sed; and 2643.5 +/- 65.9 kcal, Cyc-Ex). Relative fat intake (percentage o f total kcal/week) was significantly less for Con-Ex and Cyc-Ex than Con-Se d and Cyc-Sed throughout both refeeding periods. Discussion: Weight cycling failed to produce significant sustained effects on SEP, body mass, or food intake. Exercise training, irrespective of diet, lowered dietary fat intake.