health and being fat

[Big McLargehuge]

I didn't know where this should go, so i figured this is a good place for it.

My weight fluctuates wildly, from abour 210 to 240 lbs. It can go from one extreme to the other in as little as two weeks. I remember reading that it is better to be overweight than to have your weight fluctuate alot. I don't do this on purpose and it seems to be totoally unrealted to my diet and excersize habits, i was wondering if any body has any advice on how i can keep my weight constant (preferably at the low end).