tina42, have you thought about switching to a different form of exercise? You said in your post that you're swimming for exercise. Swimming is great for your joints, but unless you're swimming many miles every day, it's not the best exercise in the world for losing fat, sadly -- though it's good for your heart, & stress level, life expectancy, etc.

One of the reasons (supposedly) is that when you swim, the body tends to be cold and will want to maintain a layer of subcutaneous fat to keep itself warm -- this is especially true for women. (??) I know, that sounds bizarre, and I'm not sure I totally believe it, but this is what a personal trainer said to me once, so take it for what it's worth. Or dismiss it as total hogwash (I've never heard anyone else say this about swimming).

Second (and this one makes more sense to me, and I actually DO believe it), swimming uses mostly your upper body. The muscles in your arms, back and shoulders are trivial compared to the muscles in your buttocks and legs. I mean, compared to the muscles in your lower body, there's just never going to be anything like as much muscle mass in your upper body. (This makes sense, when you think about it: your legs can support your weight all day, but if you were to try to "walk" on your arms you'd be able to do it for like, a few seconds, even if you were really strong).

Because the muscles in your lower body are so much more massive than the muscles in your arms, they burn many more calories when you exercise them. It just takes more fuel to power those big engines.

Third, if you've been doing the same exercise for a while, your body will become efficient at it. And the more efficient it is, the fewer calories it burns. When you switch to a different form of exercise, the new exercise will be less pleasant than your old workouts. You won't feel as strong or as graceful. You'll get tired faster. You might not get the euphoria. And it'll be harder to stick with than your old comfortable routine. But you'll burn more calories because your body is working harder.

Also there are low- and no-impact forms of lower-body exercise (stairmaster).

But, if for your temperament, it's "swimming or nothing!" then definitely swim! It won't slim you down as quickly as walking, stairmastering, aerobics, jogging, etc., but it provides a myriad of other health benefits and you will live a longer and happier life because of it.

Good luck. And don't worry. Stalls are part of the process.