2Thick,
What is the point of cardio for bodybuilders? To lose fat, right? We are not talking about anything else here, correct?
Since fat loss depends primarily on caloric deficit, then the more calories lost = more fat loss.
HIIT causes much greater caloric loss than low-intensity cardio. I don't care if low-intensity cardio preferentially burns fat calories-- that does not matter nearly as much in the overall picture as total caloric expenditure. You lose more calories and thus, more bodyfat when implementing HIIT vs. low-intensity cardio, all else being equal.
2 to 4 20-30 minute sessions of HIIT will not burn muscle unless you are lacking adequate nutrition and anabolic hormones. Neither will 2-4 60minute sessions of lowintensity cardio, ceterus parabus. However, since you burn more calories with HIIT-- it will cause more caloric/bodyfat loss.
Conclusion: HIIT is more effective for fat loss than low-intensity cardio. Owned.