Objective: We evaluated the effects of two levels of dietary fat (0 and 20g beef tallow/100g diet) and two treadmill exercise protocols (low-intensity, high-intensity) on fat deposition in rats.
Design: Male Wistar rats (n = 50) remained sedentary or were forced to run 840 meters/day, 5 days/week, on a rodent treadmill. Those on the high-intensity protocol covered this distance in less time (38 min) than those on the low-intensity program (60 min). Responses to high-fat (HF) and low-fat (LF) diets were compared within each exercise group for this 8-week study.
Results: High fat feeding, as a single factor, did not affect energy intake, carcass fat, intramuscular fat, or fat associated with any tissue studied. The HF diet also did not affect responses to either exercise protocol. The high-intensity-exercised animals had less carcass fat (LF: 21% less; HF: 33% less), smaller omental fat pads (LF: 20% less; HF: 37% less), and retroperitoneal fat pads (LF: 19% less; HF: 38% less), and lower serum triglyceride levels (LF: 26% less; HF: 41% less) than sedentary rats. Those differences were less marked for the low-intensity-exercise rat. Neither mode of exercise or diet affected lipid concentrations in hindlimb muscles, livers, hearts, or kidneys.
Conclusion: Exercised animals generally had less fat deposition than sedentary rats but this was more pronounced for high-intensity than low-intensity-exercised rats, and was not affected by feeding a 20% beef tallow diet.