My understanding is this: the best way to keep your metabolism from slowing is to eat frequently, like say (if you could possibly handle it) 6 small meals at 250 to 400
calories each (so a total of 1500 for a small person trying to lose weight, and 2100 for a medium-to-largish person) AND combining weight training. When I was 19 (yeah, I know, my metabolism has changed since then) I got to 135 lbs and 18.5%
body fat (according to a pinch-test), from155 lbs (I'm 5'7") by
cardio and
weights--not
dieting. Mind you, I was lifting pretty heavy
weights and I was really strong! That was in 2002, and there was a lot of "new" research about muscle and metabolism. So when I reach my plateau, that's my gameplan. To lift heavier
weights--it worked last time!