Health and Fitness: Shrink 2 Sizes by Summer

The ultimate shape-up plan to flatten your belly, firm your thighs, sculpt your butt, and get you swimsuit ready. See results in 4 weeks!

By Selene Yeager, Prevention

3 Fat-Burning Cardio Routines

High-intensity workouts burn more calories per minute than easy exercise; so to lose fat fast, you have to move fast. The good news is that even brief bursts are enough to get the job done. In a Canadian study, exercisers who did 30-minute workouts that included some short but hard efforts lost 3 times as much fat after 15 weeks as their peers who did similar 45-minute workouts without vigorous bouts.

Here are three 30-minute cardio workouts you can do while walking, running, cycling, swimming, using any cardio machine, or even just dancing in your living room. Each workout is based on an effort level of 1 to 10: 1 to 2: No effort; barely moving. 3 to 4: Easy effort; can sing. 5 to 6: Moderate effort; can talk in sentences. 7 to 8: Hard effort; can only talk a few words at a time. 9 to 10: Very hard effort; no talking, just breathing!

1. Pyramids Burns 145 to 240 calories*

Push for increasingly longer intervals with little recovery to go up the pyramid; then shorten the intervals on the way down. You'll keep your heart rate high to use more calories and improve overall fitness.

Minutes	Effort level
0-4	Warm up	3-4
4-5	Push	8
5-6	Recover	5-6
6-8	Push	8
8-9	Recover	5-6
9-12	Push	8
12-13	Recover	5-6
13-17	Push	8
17-18	Recover	5-6
18-21	Push	8
21-22	Recover	5-6
22-24	Push	8
24-25	Recover	5-6
25-26	Push	8
26-30	Cool down	3-4

2. Roller Coaster Burns 165 to 260 calories*

Like the carnival ride, this routine builds and builds until you hit your peak effort; then it goes back down for an easy recovery. These types of vigorous intervals give your endurance and metabolism a huge boost — even after your workout is over.

Minutes	Effort level
0-4	Warm up	3-4
4-7	Build	7-8
7-9	Build	8-9
9-10	Peak	10
10-13	Recover	5
13-16	Build	7-8
16-18	Build	8-9
18-19	Peak	10
19-22	Recover	5
22-25	Build	7-8
25-27	Build	8-9
27-28	Peak	10
28-31	Cool down	3-4

3. Chutes and Ladders Burns 155 to 245 calories*

Work as if you're climbing a ladder, then slide down to an easy pace for equal amounts of time. Because you get plenty of recovery, really push it during the intervals to maximize your cardio fitness level and fat-burning ability.

Minutes	Effort level
0-4	Warm up	3-4
4-5	Ladder	9
5-6	Chute	5-6
6-8	Ladder	9
8-10	Chute	5-6
10-13	Ladder	9
13-16	Chute	5-6
16-19	Ladder	9
19-22	Chute	5-6
22-24	Ladder	9
27-30	Cooldown	3-4