Home / / How To Get Skinny Legs: Fat Burning HIIT Workouts

How To Get Skinny Legs: Fat Burning HIIT Workouts

By Rachael Attard, Updated May 2, 2019
How to get skinny legs: Use HIIT to get results quicker

In this blog post, I’ll explain how to get lean legs by using HIIT. I’ll show you how to tailor your HIIT to make it a fat burning activity that will assist you in getting those slim and toned legs!

You may know from my previous blog post on cardio that low to moderate intensity cardio is a fat burning activity, whereas HIIT and weights typically are not.

HIIT and weights are an anaerobic activity, which means your body uses glycogen (carbs) as the main fuel source, not fat.

Cardio is an aerobic activity, which means your body uses glycogen (carbs) and fat as the main fuel source. When you do cardio your body gets into the fat burning zone.

Note that HIIT and weights typically do not burn fat.

CARDIO (longer duration steady state exercise) –> AEROBIC–> BURNS FAT

HIIT (short bursts of high-intensity exercise) –> ANAEROBIC–> BURNS GLYCOGEN


HIIT is great because it increases your general cardiovascular fitness and your anaerobic threshold. This means that during exercise your body will remain in the aerobic (fat burning) zone for longer, before switching to the anaerobic pathway.

The result? You can exercise for longer and at a higher intensity and still burn fat.


My favourite HIIT burning exercise is interval running. It similar to sprinting but they are not quite the same. Let me explain :)


If you are sprinting for 15-30 seconds at your absolute fastest speed, with a 30-second rest, your body is using the anaerobic pathway and is using predominantly glycogen. 

Sprinting is a great workout. It engages your muscles more and focuses on muscular power. So you’re likely to build more muscles with sprinting than with just steady state running.

If you don’t mind a more muscular look, then this is probably a great style of workout for you. But if you prefer a more lean and slim look, it might be best to avoid this type of training and focus on interval running instead.


If you are running at a fast but not maximum speed for 90 seconds to 2 minutes, your body will most likely remain in the aerobic zone for the majority of the time. This means you’ll continue to burn fat.

The fitter you are, the longer your body will remain in the aerobic (fat burning) zone before switching to anaerobic.

The result? You’ll burn more fat!

fat burning hiit workout


Interval running is my favourite type of HIIT. I started to use this technique a couple of years ago when I was training for a triathlon.

I used fast pace interval runs (not a full on sprint) to help me develop my cardio fitness faster. And it definitely helped with my cardio fitness, as I expected. But I also noticed something else.

You see, I’m a mesomorph body type and I can build muscle fairly quickly, especially on my legs. And interval running actually helped me lean out my legs.

And since I prefer a more lean look, I love doing exercises that help me get toned and slim without making me bulky.


If your goal is to get slim and lean legs without the bulkiness and you want to achieve it a bit faster, interval running could work very well for you. 

This type of workout will help you burn a LOT of calories and is great if you want to challenge yourself.

But there are some things you should take into consideration:


Interval running may not be the best choice for endomorphs. It may cause their legs to bulk up.

If you are not sure about your body type, I have a special quiz you can take. It will help you learn your body type in just two minutes, it’s completely free and you will get tips on how to train and eat specifically for your body type :)


If you are already in pretty good shape and you would like to do it, I would do this once per week at a maximum.

I also need to warn that it is really difficult. If you are not already fit, I would not recommend it.

But if you are sure you want to try interval running as your fat burning HIIT routine, don’t do a proper sprint. It’s supposed to be a more of a fast-paced interval run. 

This shouldn’t cause bulkiness like short and intense sprints usually do.

Also make sure you do it on a flat surface. Hill runs are great but you will build more muscle that way.

fat burning hiit workouts


  • 5-minute warm-up walk at 6-7km/hr
  • 400m run at around 14km/hr (takes about 1 min 50 secs)
  • 60-second walk at 6km/hr
  • Repeat as many times as you can. If you’re a beginner, aim for 3-5 rounds. If you’re advanced, aim for 8-10 rounds.
  • 15 minute cool down walk at 6-7km/hr

NOTE: You do not have to do your 400m run at 14km/hr. However, it must be at a pace that is fast and quite difficult for you to maintain for 2 minutes. After the 2 minutes, you should be in desperate need of a rest. Choose a pace that suits you best. :)


You can apply this same principle to other forms of gym equipment such as the bike or cross trainer/elliptical even though I have to say that those are not as great as interval running.

But if you can’t run for some reasons, here are your alternatives.


Cycling can cause bulkiness, especially if you are an endomorph body type. And even if you are a mesomorph I would still do it probably once per week.

As for the cross trainer/elliptical, I don’t think that it will really cause bulkiness.

This machine engages your quads so you can gain more leg muscle than you would like. But it’s not the style of workout that will necessarily cause your legs to really bulk up.

If you can’t do interval running for some reason, the cross trainer is the next best thing.

fat burning hiit workouts


  • Exercise at a medium to high intensity for 90 seconds to 2 minutes.
  • Have a rest or reduce the intensity for 60 seconds. I recommend a 60-second break, but if you need 90 seconds, that’s OK. 
  • Repeat as many times as you can.
  • This does not need to be done at the gym either. You could cycle outside rather than on the treadmill or bike.


If you would like a more specific workout and nutrition program to target fat loss on your legs and to build lean muscle without getting bulky, check out my 3 Steps To Lean Legs Program. 

My program contains an 8-week workout and nutrition plan for each of the three body types.

Love Rachael xx

P.S. read this blog post for a body weight HIIT circuit that won’t bulk up your legs.

Picture of Rachael

Rachael is an Australian born certified personal trainer and nutritionist who holds a Bachelor degree in Science.

After struggling for years to find an exercise and diet program that is tailored to women striving for lean and toned body with no bulk she designed her Lean Legs Program. This program is tailored to each body type and focused on helping women get toned but feminine bodies, without getting bulky.

Her mission is to empower women and help them stay in shape in a healthy and balanced way.

Leave a Reply

Your email address will not be published. Required fields are marked *


This site uses Akismet to reduce spam. Learn how your comment data is processed.

159 comments on “How To Get Skinny Legs: Fat Burning HIIT Workouts”

    Katty says:

    Hi lovely!
    I am a mesomorph and I wondering how much the bike/elliptical circuit should be? 1 hour or 30 minutes? or more???

      Lean Legs Support says:

      Hi lovely,

      Thanks for reaching out!

      We recommend that you do this cardio for a minimum of 45 mins or 2 hours max to effectively burn a huge number of calories. If your goal is to slim down your legs, I would advise that you stick to light-intensity cardio like power walking. :)

      I hope that helps. xx

    Nina says:

    Hi… I lost 7 kgs at home.. But now my weight loss has stuck. I would like to lose more. How can I restart my fat loss?

      Len - Lean Legs Support says:

      Hi lovely,

      Thanks for reaching out! <3

      This is very common for some women that's why Rachael wrote a detailed blog post with tips on how to get out of a weight loss plateau. Feel free to give it a read whenever you can and if you have more questions, you can email us at info@rachaelattard.com. :)

      Wishing you the best of luck! xx

    Isabelle says:

    Hi, I’m an endomorph. If I choose to run 2 times a week how long should I run for to not get bulky shoulders or arms?

      Len - Lean Legs Support says:

      Hi lovely,

      We recommend that you run for only 20 minutes. Running burns a lot of calories but some endomorph women (especially shorter women) can get bulky
      legs from doing it. This is because running actually does build some muscle (but not as much as resistance training and HIIT). We recommend that you monitor your progress and if you think that you’re gaining unwanted bulkiness, feel free to replace it with more power walks instead. You just need to double up the time. For example, a 20-min run should be substituted with a 40-min power walk. :)


    Ally says:

    Hi, I’m an endomorph. At what speed / length of time should I run on the treadmill to lose overall body weight without bulking up? Are there any other HIIT exercises for this besides interval running since you say it may cause endomorphs to bulk up? I just want to save time but if not, what steady-state speed should I jog at if I jog every day?

      Sanja - Lean Legs Support says:

      Hi lovely,

      For endomorphs, Rachael strongly recommends walking. Try to do as much power walking as you can, at least 5 times per week for 45 minutes per walk. You should do 2-3 days of moderate-high intensity cardio (running) only. Rachael recommends a running speed of 10-12km/hr or 6.2-7.5mph and running on a flat surface. As for HIIT workouts, Rachael doesn’t include them in the endomorph Program because they tend to cause bulkiness. However, if you would like to give it a try and see how it works for you, you can read Rachael’s blog post on HIIT workouts here :)

      I hope this helps, let me know if you have any questions! xx


    Esther says:

    Hi Diana,

    Just wanted to follow up. Do we still need to take protein shake after running? I also thought for mesomorphs, the carbohydrates and protein intakes were similar in the 30percentages.. thank you!

    Esther says:

    Hi Rachael,

    So is it better for mesomorphs to run, or power walk? I want to lose weight overall and not just my legs! Also… do we HAVE to eat post workout meals/snacks even though we’re not hungry? Thank you so much!

      Diana - Lean Legs Support says:

      Hi lovely,
      Both walking and running are great for slimming down the legs, so we recommend both! :) If you’re unable to run for some reason, you can substitute it with more power walking. Walking is one of the best workouts for leaner legs, so you would still get results.
      You don’t have to eat post workout if you aren’t hungry, but I would suggest having a protein shake.
      Eating more protein post workout will also help your muscles recover. Ideally, carbohydrate to protein ratio should be 3:1. Our favorite post workout meal is a protein smoothie with fruit and protein powder (in the morning), or BBQ chicken with roast sweet or white potato and green vegetables (at night). xx


    Michelle says:

    The reason why I do hiit-workout is because I want to lower my body fat-pecentage and get those abs. If I do this instead of the hiit workout, will I still be able to get abs?

      Diana - Lean Legs Support says:

      Hi lovely,
      If you’re an ectomorph or mesomorph body type, you should be able to do some interval running without getting bulky. This will work great for lowering your body fat percentage, but I would do other type of HIIT for abs, like the workouts in this blog post.
      Wishing you all the best! xx


    Clarissa C Arkins says:

    Just wondering about Sprint Les Mills so Spin but 30min High intensity, I have been doing it 2x week.

      Diana - Lean Legs Support says:

      Hi lovely,
      This type of HIIT workout is great because it burns a lot of calories, but it will make your legs bulky. If you don’t mind that then you should keep going, but if you’d like to slim down your legs I would recommend light intensity steady state cardio combined with resistance training instead! :) xx


    Kaede says:

    Hi, Rachael
    I was wondering how would be a good way to try and balance these work outs with high school life, because I am in high school but desperately want thinner, smaller and leaner legs. Also because my mother calls me fat. Even though everyone else says I am skinny. What can I do???

    Ann says:

    Does swimming help get lean legs?

      Diana - Lean Legs Support says:

      Hi lovely,
      Swimming is a great cardio workout for fat loss, but nothing will slim down your legs like walking and running will. If you’re unable to run or you’d like to substitute it, I would definitely recommend swimming as the next best thing! xx