muffintop-less:

Numerous studies indicate that HIIT cardio is the most effective form of cardio for fat loss. If you aren’t already, I encourage you to incorporate HIIT 2-3 times a week to your exercise regimen! HIIT can be done on any machine at the gym, outside, at a track or even with a jump rope. =)  

A simple HIIT workout:
5 minute warm-up jog
30 second all-out intensity sprint
1-2 minute moderate intensity jog or walk to recover
Repeat the sprint/recovery cycle 6-10 times
5 minute cool-down jog 

I just want to add that to be effective don’t just go with what you think is “all-out.” The effectiveness research has demonstrated was for 30 second intervals (4-6 cycles) you must be at 100 percent of your maximum heart rate (MHR) and for 1 minute intervals (10 cycles) you must be at 90 percent of your MHR.

Many times people feel like they are working harder than they ever have, but in reality their heart rates are not where they should be for HIIT to be effective. To have an effective HIIT workout begin by calculating your MHR which is the maximum number of beats per minute. For example, using the simplest equation (MHR = 220 - Age) a 17 year old would have a MHR of 203 beats per minute. Divide 203 by 6 to get number of beats per 10 seconds, which is 33.8 (this allows you to check your pulse for 10 seconds versus 1 minute). So, after a 30 second HIIT interval at 100% MHR a 17 year old should have 33-34 beats per 10 seconds.