The key to fat loss is HIIT.  HIIT is the most effective form of cardio. The key to HIIT is the high and low.

During the high you really need to go as hard as possible so I recommend counting your reps during the first round.  Then in the following rounds, try to match or beat those reps during each round of highs. If you are able to have a conversation while you are in your high period then you are not going hard enough.

The low is basically your active recovery period so you need to stay active even if it is just walking in place.  I have seen others recommend doing two equally difficult exercises for the entire duration of your HIIT. That will cause you to decrease your intensity over time. To get the most effective HIIT session you really want that up and down momentum.

My current HIIT routines for the next few weeks are:

40 seconds of no rope jump rope for the high and 20 seconds of toe touches for the low
30 seconds of skaters for the high and 30 seconds of high knees for the low

I rotate these routines.  I will switch out my HIIT routines each month for variety so my body gets a new challenge and you should do the same. With any exercise routine, when your body becomes accustomed to the exercise it starts to plateau.

You can pick one of the above routines or create your own from the lists below.  Set your interval timer to 30 second intervals for a total of 15 minutes.  For more challenging HIIT routine you can increase your high to 40 seconds and your low to 20 seconds. Because of the intensity of HIIT you do not want to do these more than three times a week.

There are many different exercises you can do, including:

Highs:

Mountain climbers
Jumping lunges
Jumping squats
Burpees
No rope jump rope
Kettlebell swings (see below)
Jumping jacks
Box jumping
Skaters or Lateral jumps (see below)

Lows:

Walking in place
High knees
Toe touches (swinging leg up and reaching toward toe)

Skaters or Lateral Jumps:

Kettlebell Swings:

Need an interval timer? You can purchase this cute pink Gymboss, download an interval timer for your smartphone, or use this free timer online. It all depends on what works for you.