As much as we would like to think it would, no, jalapenos and other spicy foods do not help you lose weight.
There's some (small) evidence that eating really spicy stuff can give you a brief metabolic boost, but the effect is not permanent, and the more sensitized you are to it, the less it affects you. It's going to be such a minuscule amount that it would be silly to count on it for weight loss. :) Especially since you're unlikely to actually eat just a jalapeno, and will probably include it with something else that would offset the burn. So with a very, very big asterisk on that, yes, it can, but do not expect it to increase it enough to make a significant (or any) difference on the scale. ;)
For example, I eat a lot of spicy foods. At least twice a week, I'm getting some serious heat... but I assure you, I'm quite overweight!
Writer, mother, wife, and breadwinner. I love to run, but running doesn't love me, so I'm switching to my low-impact bike.
I'm not pregnant, just fat: My blog. fatnotpregnant.blogspot.com/
| current weight: 190.6