When your dress is a little tighter than you want it to be, you can help make it a little roomier without spending extra time in the gym. Here's how to get more bang from every workout bout.

1. Keep moving Do your strength moves as a circuit-perform one after the other without resting-and you'll burn as many calories as you would during a moderate cardio session. What's more, research shows that this type of training keeps your metabolism elevated for up to 16 hours after your workout.

2. Don't tune out when you run You push harder and move quicker (read: burn more calories) when you know how much farther you have to go, researchers say. So map your route and look for mile markers to cue you to sprint to the finish. Make it feel easier: Research shows that a workout session feels easier to people who are listening to music.

3. Get in the game during cardio A Medicine & Science in Sports & Exercise study found that people who rode stationary bikes with interactive programs torched more calories than those who used game-free bikes.

4. Use intervals to your advantage Amp up your heart rate by using intervals - that's when you alternate spurts of high-intensity exercise (for instance, increase your speed or incline for a minute) with moderate-intensity exercise (decrease your speed or incline for a minute) and repeat. Working at a higher intensity allows you to burn more calories both during your workout and for several hours afterward.

5. Breathe a little heavier on the elliptical machine Don't gauge your intensity on this machine by how fast you're going. "Because they're moving so much, most people think they're working much harder then they actually are," says Jay Blahnik, spokesman for the Nautilus health and fitness group. To exercise vigorously enough to get more calorie burn from this machine, you should find it tough to eke out more than a few words in conversation.