The effect of repeated episodes of dietary restriction and refeeding on systolic blood pressure and food intake in exercise-trained normotensive rats

Abstract

To explore the effects of weight cycling and exercise on blood pressure and macronutrient intake in Sprague-Dawley rats. Research Methods and Procedures: 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. Discussion: Weight cycling failed to produce significant sustained effects on SBP, body mass, or food intake. Exercise training, irrespective of diet, lowered dietary fat intake.