I love HIIT workouts for fat loss. Why? Because compared to steady state cardio (like jogging on a treadmill for an hour) HIIT can burn more calories in a shorter amount of time. It almost sounds too good to be true. Its not! By the way, HIIT stands for “high intensity interval training.”
If you want to understand why HIIT workouts are great for fat loss than you have to understand the “Afterburn Effect”
The afterburn effect is also known as “excess post-exercise oxygen consumption” or EPOC. You see, much like a car is still warm after taking it for a drive, your body is still warm after a workout session. This “warmth” or heat is your metabolism burning calories. How long your body “stays warm” after a workout is proportional to the intensity of that workout.
And to understand workout intensity it’s important to know the difference between aerobic and anaerobic respiration
Aerobic vs. Anaerobic Respiration
During a workout there are two forms of energy pathways that your body can use depending on the environment it’s in. There is aerobic respiration which utilizes oxygen to create energy (high oxygen environment), and then there is anaerobic respiration which does not use oxygen (low oxygen environment).
Going on a nice and easy jog utilizes aerobic respiration. The oxygen you breath can be transported into the muscles to sustain them, and the muscles utilize the oxygen at a rate that does not exceed the rate of oxygen consumption.
Doing a hard, intense sprint on the other hand requires immediate energy stored in the muscle for fuel. After a few seconds of sprinting, your body runs out of usable energy. Aerobic respiration can’t transport oxygen fast enough into the muscle tissue to sustain the energy demand. The muscle has to rely on anaerobic respiration instead, which, although is faster, is almost 20x less efficient when compared to aerobic respiration. Anaerobic respiration breaks down the glycogen in the muscle into lactate and ATP (usable chemical energy). During an intense workout, you can feel the burning, tightening sensation as the lactic acid byproduct builds in the muscles. This is a result of anaerobic respiration.e
The “Afterburn” Effect
Once a workout that utilized anaerobic respiration is completed your tissues are oxygen deficient and are in “catch up” mode. Think about your actions after completing an intense sprint workout: you’re bent over at the hips, gasping for air like a fish out of water. This is your body trying to get as much oxygen into the tissues as fast as possible and is exactly what excess post-exercise oxygen consumption is. EPOC is mainly caused from working your body at an intensity where oxygen absorption cannot keep up with the oxygen demand in the muscles.
Science has shown the more intense a workout is, the longer the EPOC duration. The longer the EPOC lasts, the longer your metabolism stays elevated. A prolonged elevation of metabolism results in more calories burned. And remember you continue to burn calories even after the workout has been completed.
HIIT has been shown to increase mitochondrial biogenesis in the muscle tissue. Having health mitochondria is key for a healthy metabolism. Mitochondrial health is also paramount when it comes to living a long and healthy life.
More Muscle Recruitment
During a n explosive HIIT workout, you engage your fast twitch muscle fibers first. As your fast twitch muscle fibers begin to fatigue, your muscles recruit your slower muscle fibers to pick up the workload. Therefore, during a HIIT session, you are effectively training all of the different muscle fibers. On the other hand, when you perform slower steady state cardio exercises, like jogging for example, your fast twitch muscle fibers are never engaged.
HIIT Workouts For Fat Loss Examples:
Sprints are a great HIIT workout for fat loss. Try doing 8-10 repetitions of 200m sprints on 120 seconds. The word on means that the rest period is dependent on how long the work period takes. So, if you complete the 200m sprint in 30 seconds, your rest period would be 90 seconds because 120-30 = 90. If it takes you 60 seconds to complete the sprint then your break period would be 60 seconds long.
If you want to UP the intensity try doing 10 reps of 200m sprints on 90 seconds!
I particularly find 200m sprints to be one of the toughest distances to run. A 100m sprint is over in 15 seconds or less, but a 200m sprint lasts close to 30-40 seconds. This is a long amount of time to be going 100%, all out, which is why it is such a challenging distance to sprint.
Tabata circuits are another great HIIT workout for fat loss. What is a tabata circuit? A tabata circuit is a particular type of interval workout that consists of 8 rounds of 20 seconds of work and 10 seconds of rest. In total the workout is only 3 minutes and 50 seconds long. That might not sound like much, but during the 20 seconds of “work” you are giving it your 100%, complete all. Whats great about tabata workouts is they can be applied to almost any cardio equipment like a treadmill, bike, row machine, or even body weight exercises like burpees.
Try this Tabata Workout: Head to the treadmill. Set the incline to 12.5%. Set the treadmill speed to about 7-9 mph (I like to use a 20lb weight vest and shoot for 7.5-8 mph for my speed). Hop onto the treadmill and begin your first 20 seconds of work. After the 20 seconds is complete, place your feat outside of the tread allowing the tread to still run while your feet are resting on the outside portion of the treadmill (Warning: This is dangerous; be careful). Try a slower test run to before going full tilt). Repeat this 7 more times to complete 8 rounds. You will be spent afterwards and will definitely be experiencing some EPOC.
The row machine is my favorite machine for fat loss. Why? You can do a multitude of HIIT workouts for fat loss on a rower. Pictured below are some example workouts from a great book called “Power, Speed, Endurance” by Brian Mckenzie
These row workouts are a great way to break out of the monotony of regular steady state cardio workouts. Try a few!
The assault bike or “fan bike” is another great fat loss machine. My favorite HIIT workout for fat loss using this machine is the following: 10 rounds of 30 seconds of 100% all out effort, followed by 1:30 of rest. This is one of the hardest cardio workouts I have experienced. It completely burns out the quads as well.
It takes some real mental toughness to push through all 10 sets at maximum effort. Whats great about this workout is not only will you burn fat, but you will also increase growth hormone secretion. I got this workout from Dr. Mercola’s Website which documents exactly why this workout works.
Cross-Fit Style Workouts
Say what you want about cross-fit, but from what I have personally experienced and based on what others have experienced, I believe it is the best way to get in shape. And by in shape, I mean muscle gain and fat loss; improved body composition. Cross-fit is comprised of fast paced, HIIT stye workouts. What makes it different is instead of only doing cardio, you are doing explosive lifts like power cleans or snatches that really get the metabolism firing to torch fat.
Here’s a crossfit workout example called the “Fran”
The Fran consists of…
- 21 reps of thrusters with 115 or 95 lbs
- 21 pull-ups
- 15 reps of thrusters with 115 or 95 lbs
- 15 pull-ups
- 9 reps of thrusters with 115 or 95 lbs
- 9 pull-ups
Do this as fast as possible.
It might not look like much, but doing thrusters for time really taxes your musculature and cardiovascular systems like no other workout.
Home HIIT Workouts For Fat Loss
At the end of the day, you don’t need fancy rowers, assault bikes, or cross fit memberships to achieve a great HIIT workout session. A workout comprised of push-ups, squats, burpees, jumping jacks, and tuck jumps performed at a fast pace can be killer. And remember when it comes to HIIT, the more you put into the workout the better your results will be!