Hello and welcome!
I'll be frank, the waist trimmer belt isn't going to do anything for you except heat up your midsection and cause you to sweat more and thus lose water weight. This could be ok if you're going for a night out or something. I think fitness models purposely dehydrate themselves before competitions to better show off their muscles. But for you, and your goals, no it's not very useful and I don't think the claims are true. The average person will burn 75 calories in 15 mins if they keep their heart rate elevated.
Additionally, your body needs water to burn fat so I actually regard this tool as counter productive. It sounds like you're doing a good job at keeping hydrated though.
I hope you're not too disapointed but here are some tips on how you can boost your workouts without gimmicks (mostly regarding resistance training).
I'm not sure what kind of resistance training you're doing.... but here are some tips.
If using bodyweight as resistance only, do repetitions until the targeted muscles burn and it's somewhat painful, and you can't finish your reps.
Do the harder versions of the exercise, or, make up a harder version of the exercise. Just get to the point of exhaustion (and don't be afraid to rest for a minute before moving onto the next set or exercise).
If using weights, you may not be using enough weights. If you're doing 8-12 reps without feeling exhausted you aren't lifting the right amount of weight.
Start by increasing by 3 reps than normal. If you aren't getting to the point of exhaustion it's time to move up.
For small muscle groups add 3-5 lbs, for large groups add 5-10 lbs. Follow these guidelines until you find the weights for each exercise that will exhaust your muscles.
If using resistance bands, fold the resistance band over onto itself, or step on it (when doing standing-type exercises) to make it shorter, or gather up two or more resistance bands together, or buy a tougher band (less stretcy). All of these these have the effect of increasing the resistance, making you work harder, and making you get to the point of exhaustion.
Raise your heart rate, when doing your dvd, if it isn't already integrated, pause and raise your heart rate by doing something that requires an intense effort for a short burst of time (10-40 seconds). Do jumping jacks, ski steps, squats, squat jumps, jog in place, hop up and down, moutain climbers, anything! Anything you can think of that will make your heart rate go up. To get an intense level, do them as fast as you can, so fast that you are relieved when you stop after the 10-40 seconds. Take a short break for 10-30 seconds and repeat, or, go back to your dvd. Do this throughout your workout.
I hope this helps!
[DATE]: WEIGHT (CHANGE/TOTAL)
[Oct 07, 2010] 176.5 lbs (Start)
[Nov 22, 2010]: 173.9 lbs (-2.6/-2.6)
[Nov 30, 2010]: 173.8 lbs (-0.1/-2.7)
[Dec 06, 2010]: 171.2 lbs (-2.6/-5.3)
[Dec 14, 2010]: 172.5 lbs (+1.3/-4.0)
[Dec 20, 2010]: 169.8 lbs (-2.7/-6.7)
[Goal Weight Range]: 118 lbs to 126 lbs
Female, 22, Height: 5'3"