There is no rule that says you must wear a heavy-weight gi... In the summer (or in the great state of Texas), I'd hang up the heavy-weight gi and put on a light-weight version. As for opening up, it sounds like you need a slightly different size and/or I hope that they allow light T-shirts or something under your gi. Many dojos will even suspend normal dress requirements during the summer and allow students to workout in a T-shirt and gi-pants.
My wife never liked the brute strength of kara-te styles and after awhile, went to studying ju-jitsu. There are styles of ju-jitsu that emphasize agility, pressure-points, leverage, and using your attackers strength against them. With both of us as Dan ranks, and me literally twice her size (I can bench her and we'll be making a snowman in hades before she could return the favor), I have ended up on the floor 10' away, looking up and thinking "damn" on more than one occasion.
It depends on what YOUR
I just want to encourage you to do the research and decide what you want. Also, to not delude yourself that you can defend yourself without some strength. While what I say about my wife is true, she's always worked to maximize her advantages and try to eliminate her disadvantages.
In other words, don't take "aerobic kickboxing" and think you can defend yourself. And don't think that the psycho punk who whats your money and more will do more than laugh if you throw a little fluff kick or soft punch. I studied pressure-points for years, and when I did my great shot on the street once, the fool didn't just stand there and let me smack the point(s)! Hmmmm... Not like the dojo.
If you want to learn some real self-defense applications, find someplace that does realistic scenerio training as a suppliment to the kata/kumite/etc... Once when the wife tried a ju-jitsu move on an attacker he just grabbed her "differently" and laughed (PCP...) She was fortunate that she knew strikes as well... her next technique worked just fine for her escape after she had "softened him up a touch".
Chances are you'll never need to use your art for self-defense, but it's best to understand where you're at before the proverbial "OH $hit" moment.
Good Luck... If there's anything we can do to help, just ask... we'll do our best.
[This message has been edited by Panther (edited November 08, 2000).]