I have a question I'm hoping someone on this board can answer.

Since July, I've had a pretty regular routine of doing 30 minutes of cardio on the elliptical (on a challenging level for running), plus 30-60 minutes of weight training on machines, at the school gym. The school gym closed for Christmas break a week and a half ago, so I started using the office gym (a room with a stationary bike, an elliptical, and a Bowflex).

Because I'm not familiar with the Bowflex and didn't feel like teaching myself for the two weeks I'd be using that gym, I ran on the elliptical only. I did it for 30 minutes, on a challenging level, 5 days this week.

Apart from the beginning of my weight loss journey, I usually lose somewhere between 0.5 - 2 lb. a week.

Somehow, I managed to lose 3.2 pounds in the first week of using the office gym equipment. I stayed within my "weight loss" calories (1,200 - 1,600) all week, minus one day that I ate maintenance calories. Nothing changed last week, except where I was working out.

Is there any explanation for this? I do feel like the office elliptical machine has challenged me more than the school gym in that I feel like I'm walking briskly up a hill instead of running. (On the school gym machine, I was more focused on my speed and distance.) Could it be that the office machine's higher resistance is burning more calories than the gym? Do you think I could replicate this experience by upping the level I do at the school gym?

I'm not interested in burning the same weight every week since I don't think a 3.2 pound loss is healthy for my size, but I am interested in understanding why this happened. Thanks in advance!

Would you really lose weight from losing muscle in only 10 days' time? That seems pretty fast. I've read through various sources that it takes much longer than people think to both gain and lose weight from muscle gain/loss. (I.e., people think they've gained weight because of muscle gain after only a week of working out when that's really unlikely.)

My calorie range has stayed the same, but I did eat a lot more chocolate last week with Christmas treats floating around. (Is it possible chocolate = more calories burned? I wish! )

But if that's the case, I'll be excited to get started again at the school gym when it opens on Tuesday! I'm not interested in losing weight through muscle loss. Thanks for the comment!

I've read that it takes 3-4 weeks for muscle deterioration to occur. Then again, I've only been able to find information about this on body builder forums, nothing scientific or professional.

I weigh in once a week, and the previous Friday only lost 0.6. Maybe my body was holding on to water weight that Friday, which was then released before my next weigh-in when I lost 3.2. It's just odd to me since I had two holiday meals in between those weigh-ins. I didn't binge or anything, but I did eat a bit, enough that a 3.2 pound loss seems crazy to me. That would explain a lot though. My workouts have been challenging, but nothing that would cause a 3.2 lb. loss in my mind.

Thanks so much for the help! I had not even considered that, but it does make a lot of sense. Happy New Year!

Any change in routine will change how you lose weight. Our bodies adapt to our fitness routines and become more efficient over time and burn less cals doing the same exercise.

I hear ya. I think a big part of my success in losing weight has been that I continuously up the intensity level once something becomes "easy" or at least "less hard."

I try to consistently challenge myself, but I could tell a major difference in going from level 9 on the elliptical at school to level 5 on the office elliptical. If I didn't have my pride standing in the way, I probably would have started at a 3 on the office machine, but I couldn't go lower than 5 without feeling ashamed. Ridiculous, I know. But more weight loss, so yay!

By no means am I an expert, but I do have a little experience with what you're talking about. While I was in the Army, I would regularly workout with both a cardio and muscle building regimen. However, when my fitness test was upcoming, I focused only on cardio because I was able to burn a few more pounds than normal during that time and it allowed me to be a bit more competitive. The muscle I'd already built didn't go away within that week (at least substantially), but a cardio focused training routine helped me to lose a few extra pounds. I'm not sure if the benefits were mostly in my head or not, but I seemed to feel like I could perform additional situps and pushups with the lesser weight and, of course, my run time was slightly better than usual.

I guess my point is that, yes, you may be able to lose a bit more weight in the short term, with strict cardio, but as some of the others mentioned a long term mix of cardio and weight training will support maintained weight loss.