walking...to lose weight?

I LOVE to exercise. Cycling and weights, specifically...but in my busy life, those things rarely happen, if ever. In addition to the fun I have exercising, due to my body type/metabolism/genes (probably), it is somewhat of a neccesity. In fact, compared to some I know, I seem to need to exercise a bunch more for seemily less "effect". Sure, I am not really psycho with my diet, and that likely plays a part, but I generally try to watch at least somewhat wvat I eat...

So a few years back I tried jogging. If you must know, it isn't my favorite thing, but I figured I got "more bang for my buck" (you know, run really hard for 20-30 min, etc.). It did help me lose a bit of weight and I felt better/more fit overall, but I have essentially "lived" in the 180s for a few years...despite regular exercise. Well, a couple weeks I pulled my left calf muscle. I tried to tough it out on a couple runs, but both times I had to stop about 15 min. in as I could no longer continue...

So, I decided to start walking instead (you know, "speed walking"). All last week, I would get up at my normal time (6 am), get dressed, fire up the ipod, and go walk. Only main difference is that I would go for longer, more like 40-45 minutes. On Friday (my day off), I even went out to a trail nearby and walked for an hour or so.

Well a funny thing happened: I lost 3+ pounds since Friday! And I certainly didn't eat "good" over the weekend...

What is going on????

I am the king of yo-yo weight...it is obviously easier to gain, but I can gain like 5 lbs. over thanksgiving, but i can lose it all back in a couple weeks... I even have a history of big swings. In 1994, I went all psycho (diet and exercise) and lost over 50 lbs. I stayed in usually decent fitness for like 7 years, until I (of course) got engaged, and for some reason I "forgot" all that discipline when I moved to houston pre-marriage (Missy was still in Ft. Worth) and popped up like 40 lbs again. I basically ballooned due to less exercise and a lack of discipline. So thankfully (and slowly...probably a better method) I did drop about 30 again...and have been able to stay generally there for 5 years or so. So we'll see...