High Intensity Interval Training (HIIT): Best Cardio to Burn Fat

When most people think of cardio, they think of long, boring jogs, or endless hours on the elliptical. I’ve got good news for you: there’s a method of cardio that takes much less time and is far superior to jogging to help you burn fat. It’s called High Intensity Interval Training (HIIT) and this article will give you the basics so you can take your body to a new fitness level.

The picture to the right shows an extreme example of the different training outcomes of a marathoner (“steady state” cardio) and sprinter (high intensity interval training cardio). While these people obviously have different body types and genetics, the photo is still revealing.

What is High Intensity Interval Training?

High Intensity Interval Training involves alternating between very intense bouts of exercise and low intensity exercise. For example, sprinting for 30 seconds, then walking for 60 seconds is high intensity interval training. HIIT can be used both anaerobically (in the gym with weights) and aerobically with cardio.

Why Is HIIT the Best Cardio to Burn Fat?

Exercise physiologists used to believe that “steady state” cardio was superior for fat loss because relatively more fat is used by the body as fuel at lower exercise intensities than at higher intensities. The “Fat Burning Zone” shown on most cardio equipment as only 60%-65% of max heart rate is really a myth and is NOT optimal for burning fat. Yes, you burn more fat relative to glycogen when going for a walk, but what we care about is total fat burn. At higher intensities, you are burning far more fat, even though the fat/glycogen ratio is lower.^1 2 In addition, interval training allows you to exercise at very high intensities for a much longer period of time than steady state, so you burn more fat.

As an added bonus, there’s also an afterburn effect known as EPOC (excess-post exercise oxygen consumption). You increase your metabolism and burn more calories for up to 24 hours after interval training, whereas going for a jog burns almost NO calories after.

Other HIIT Benefits

There are a number of great benefits to High Intensity Interval Training besides serious fat burn that include:

• Increased Aerobic Capacity – The amount of oxygen your body can use (oxygen uptake) is increased, so your overall aerobic capacity can increase faster than with low intensity endurance exercise³

• Increased Lactate Threshold – Your ability to handle increased lactic acid buildup in your muscles increases

• Improved Insulin Sensitivity – Your muscles more readily suck in glucose, instead of the glucose going to your fat stores^4 5

• Anabolic Effect – Some studies show that interval training combined with consuming slightly more calories than you burn creates an anabolic effect, which helps you put on muscle. The opposite occurs with steady state cardio, which for long durations is catabolic.⁶

Sample HIIT Workout

If you are a beginner, I would recommend only trying HIIT if you can do a session of cardio for 20-30 minutes at 70-85% of your max heart rate. You can still try interval training, but at a lower exercise intensity and beginners should always wear a heart rate monitor.

NOTE: Interval training should begin with a 3-5 minute warm up and end with a 3-5 minute cool down to prevent dizziness, or nausea.

Here’s a sample HIIT workout that’s simple, but effective:

60 Seconds Sprint/Fast Jog
120 Seconds Walk/Slow Jog

I do this HIIT workout all the time on a treadmill, elliptical, or outside. The duration of “work” is 60 seconds, and my “rest” is 120 seconds. The work/rest ratio in this case is 60/120, or 1 to 2. I shoot for 5-10 cycles, depending on the type of cardio I’m doing and if it’s right after strength training. The better shape you are in, the higher intensity you can handle and the higher the work/rest ratio. For example, well trained athletes can use a 2 to 1 work /rest ratio, so they are sprinting for 120 seconds and only resting for 60 seconds. That’s tough!

Any type of cardio can be used with interval training, but I would caution against running more than a few times per week, because the demands on your metabolic system and joints are significant. For beginners, I recommend the elliptical, which is lower impact. Swimming, jumping rope, cycling etc. can all work well as training modalities.

I rarely go for just a jog unless I just want to clear my head, or get a little sweat. Jogging is child’s play compared to HIIT, which is substantially more effective to help you burn fat in less time and take your body to a MUCH higher fitness level.