Speaking is a good way to lose water weight. Nervousness causes sweating and public speaking induces lots of nervousness and lots of sweating.

The best way to manage nerves is probably to over-prepare. Go over your notes or outline several times and rewrite or reorganize as needed. Practice the speech a few times. Use a clock or watch to time yourself as well.

Knowing your audience well does help. If you know what listeners want and need, you can be more confident that your presentation will be interesting and useful for them.

Know the setting of your presentation. Visit the site beforehand if possible, to get a feel for what it will be like to get up there and talk. Know where to put your LED projector or laptop and where you could stand.

Have back-up plans. Power goes out. Computers crash. Audio-visual equipment breaks down, or isn't there as promised. Professional speakers always have an option available. If you know what could go wrong and how you might cope, your stress level should go down.