I want to help women achieve bodies that are healthy and that they are comfortable in. One of the ways I do this is by teaching women how to lose extra body fat and weight in the most efficient way.

I believe that getting your body in the fat burning zone is a great way to burn more fat.

In this blog post, I’ll explain what the fat burning zone is, how it works and the best way to exercise to lose fat fast.


When you work out, most people think that you need to give the workout all the energy you have and to work out as hard as you can. After all, this is what makes you burn the most calories!

However, the fat burning zone theory says that you shouldn’t push your body all the way to 100. Instead, you’ll burn the most fat when you working at 60 to 70 percent of your maximum heart rate.

Basically, what this means, is that fat burning occurs when you limit the intensity of your workouts to a specific heart rate zone.


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In order to understand how the fat burning zone works, we need to understand how the body burns fat.

Our bodies are constantly turning carbohydrates and fat into energy that we can use. This energy is called adenosine triphosphate, or ATP. 

The ratio that your body uses carbs versus fat is going to depend on several things, including your activity level.

In general, though, our bodies are going to do what’s most efficient. In most situations, they are using a combination of fat and carbohydrates stored in our body to make energy and help us function.



Your body needs oxygen to convert fat into ATP. When you’re doing low to moderate-intensity exercise, you’re able to breathe easier and your body gets more oxygen than when you’re pushing hard in a HIIT or other intense workout.

The most efficient thing your body can do during lower and moderate forms of exercise is to turn to your stored fat into energy.

So according to the fat burning theory, you should do long low-intensity exercises in order to use up fat storage and to burn enough calories in order to see weight loss.


When you start to push your body into really hard workouts, your body needs to be able to find energy quickly. But when you’re working out hard and you’re struggling to breathe, your body doesn’t have enough oxygen to burn fat.

So instead, it turns to glycogen (or your body’s stored carbs) in order to get energy fast.

When you do a high-intensity workout, your body burns through your glycogen stores and may eventually turn back to fat burning depending on the length of the workout, and your body’s amount of stored carbs.

But if you eat before doing a high-intensity workout (and especially if your diet is high in carbs), your body will most probably burn way more carbs than fat.


There’s a direct connection between your heart rate and the intensity of your training. The harder you train, the faster your heart rate gets.

Depending on how hard you train, your heart rate can be in 5 different training zones.

For example, if you’re power walking for an hour, your heart is not going to pump as hard as it does when you’re doing something more intense like sprinting.

Knowing which zone you’re in will help you understand how your body is making energy and whether you’re burning mainly fat or carbs.

If you want to keep track of heart rate training zones, you need to know your maximum heart rate (more details below) and what each zone means.

Here are the 5 heart rate training zones and each of them can be estimated based on your heart rate!



In this zone, you’re working out at <60 percent of your maximum heart rate.

Your heart rate is in this zone when you’re just moving around without doing anything remotely challenging.

It’s like when you’re rewatching Friends and going to the fridge to grab a piece of cake. ;)


Just above the warm-up zone is your fat-burning zone. In this zone, you’re working out at about 60-70 percent of your maximum heart rate.

This level is all about endurance. Your body will be able to use oxygen to convert fat to energy, and you’ll find that you’ll be able to exercise for a while in this zone.

You’ve totally got this!

You’ll most likely be in this zone during low-intensity cardio like going to long power walks.

I have a really detailed blog post on how to use low-intensity cardio to burn more fat and get lean so make sure to give it a read. :)



We’re picking up the pace here!

In this zone, you’re working out at about 70-80 percent of your maximum heart rate.

You should be able to talk and be relatively comfortable. However, you might find yourself sweating and breathing harder during this stage.

So it’s challenging but still doable!

In this zone, you’ve also reached what’s called the cardio zone. You start to burn a lot of calories relatively quickly in this zone.

The calories you burn here split evenly between your fat stores and glycogen (carbs). However, the fitter you are, the more your body will be able to rely on fat for energy, and not carbs (this is known as the anaerobic threshold).

Although you may not burn more fat than carbs, you will still burn lots of calories overall. 

You’ll most likely get to the cardio zone when you’re jogging, swimming or cycling.


Now we’re getting serious!

You’re working out at about 80 to 90 percent of your maximum heart rate.

You’re struggling to breathe and may find that it is becoming difficult to hold a conversation.

Over time, working out in this zone should help you to push harder or go faster.

Here you’re definitely burning tons of calories and more carbs than fat.

Resistance training is considered to be a high-intensity activity. Also, resistance training raises your metabolism which means you’ll burn more calories while resting.

So, even though it may not help you burn more fat, it will definitely help with weight loss and increasing your fitness.



This zone feels like when your PT tells you to push through the last 30 seconds of your 3 rounds of HIIT!

In this zone, you’re working out at about 90 to 100 percent of your maximum heart rate.

You’ll probably only be able to stand this zone for a few minutes. Your body’s respiratory and blood system will be working as hard as possible, and you’ll be panting and unable to talk.

Doing interval training in this zone (such as during a HIIT workout or sprinting) will make it easier for your body to burn both carbs and fat. You’ll also continue to burn calories after the workout is over, and your metabolism will temporarily increase.

If you’re new to exercising or haven’t done much high-intensity workouts, you might find that you can’t handle this intensity at all. So it’s important to listen to your body and take it easy.


First, you’ll need to know your maximum heart rate. Your maximum heart rate = 220 minus your age. So for example, if you are 25 years old, your maximum heart rate is 220 – 25 = 195 beats per minute (bpm).

To calculate your fat burning zone of 60 to 70 percent of your maximum heart rate, follow these equations:

  • Maximum heart rate x 0.6 (60%)
  • Maximum heart rate x 0.7 (70%)


Here’s what this would be for a 25-year-old.

  • Maximum heart rate = 220 – 25 = 195 beats per minute (bpm)
  • 60% of your maximum heart rate is 195 x 0.6 = 117 bpm
  • 70% of your maximum heart rate is 195 x 0.7 = 136.5 pm

So for a 25 year old person, the fat burning zone is when your heart rate is between 117 – 137 bpm.

If this is too technical for you, I recommend you try to just notice your body’s signs. In the fat burning zone, you should be able to talk and continue at the pace you’re going for at least an hour.

When I go for walks, I try to be in the fat burning zone as I’ve found this really helps to keep my legs slim.

I aim to walk at a medium-fast pace, and my heart rate is in the right zone. I don’t need to go full speed and feel really puffed out. 


Different types of workouts give your body different benefits. To help you see how they can do this, let’s imagine a few scenarios:


Let’s imagine that after work, you decide to power through an intense HIIT workout or some resistance training.

This workout is intense, so your body needs a quick form of energy. Your body is struggling to use fat as an energy source because you’re breathing hard and aren’t getting enough oxygen to convert fat to energy.

But since you have eaten throughout the day, the carbs stored in your muscles are readily available, and your body doesn’t need oxygen to turn them into energy. You may eventually burn fat too, but the percentage of carbs burned will be higher than the percentage of fat.

This intense workout burns a ton of calories which is great for weight loss, helps boost your metabolism, and helps build some muscle that’s great for toning up.



Now, let’s say it’s morning and you haven’t eaten yet. Your body is low on carbs and you decide to go for a power walk to start your day. This is called fasted cardio and it’s great for fat loss.

Your body isn’t being pushed too hard, so you’re getting plenty of oxygen. This, along with not having too many carbs in your body, means that your body starts to use fat for energy.

Fat is more abundant and is a great source of slow-burning energy which makes it perfect for the times like these.

Going for power walks and doing other low-intensity workouts is great for getting slim legs, it prevents burn out, and helps you recover from more intense workouts. :)


Sticking to one form of exercise will prevent you from seeing the good results that the other forms can bring.

I believe the fat burning theory is based on scientific facts, but I still encourage you to do more than just low-intensity cardio. The best way to lose weight is to combine low and high-intensity cardio with resistance training. :)

This is why I designed my own workout program that combines fat burning exercises and resistance training. It’s designed to help you get lean and toned in just 8 weeks.

Here are some of the lovely girls who did my Lean Legs Program! :)

lean legs program results

Love Rachael xx

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.

24 Responses

    1. Hey lovely! Tracking your calories every day is a difficult task so it’s not always recommended. But if your goal is to slim down your legs or lose weight overall, it would be best to follow the right macros for your body type and apply a calorie deficit to your daily calorie intake. :)

  1. Hello Rachael! I’m 21 and I’m medical student. I got to know about your program a year ago and it helped me a bit during quarantine. But now we have to go to our practical classes at the hospitals and I’m also working as a nurse. Every day I come home late and I feel really tired. That’s why I can do exercises at least 2-3 times a week.Have you got any useful tips for me? Should I,for example, do exercises 3 times a week, but more than 45 seconds or something like that? Please help me.

  2. thank you so much for the info i’m a guy and found info helping me to lose weight i always ran or worked out since the army days i wanted to know why such a low heart rate weight when working out and now i’m 61 and now the science of losing weight is important to me and btw great smile

  3. Hello! I’ve just started! Before joining, I was doing a lot of HIIT and jumping rope. You advise to avoid jumping rope and do walking or running instead. I absolute hate running. I can skip for almost an hour without any problem, but running is not for me. So my question is, is it ok to only do power walking? But that means my heart rate will only stay at Zone 2. Also, when I follow the resistance training, 3-4 times a week, my heart rate is really only at Zone 2. So, am I going to achieve the results with my heart rate only staying at Zone 2, or do I somehow need to get to at least zone 3. With my previous workout plan, getting to Zone 3-5 was no problem (but have not slimmed down). Your guidance on where my heart rate should be and how many times a week is much appreciated!

    1. Hey lovely,

      It is so exciting that you are starting your fitness journey! :)

      Skipping is great cardio but can’t be a substitute for walking and running because it won’t slim down your legs. It does burn a lot of calories which is great, but the motion uses your calves heavily. Skipping will most likely contribute to bigger calves and can make your legs bigger all over.

      Since you are not a fan of running, Rachael suggests more power walking instead. It would be best if you’d double up on the time invested. E.g. if the run was supposed to be 20 minutes long, you should do a 40 minute walk.
      I know this sound like a lot of walking, but it is the best cardio method for slimming down. :)

      Don’t be that focused on the numbers, what matters more is that you do your activities and the result will come! :)

      Enjoy the process!


  4. Hi :) Thank you for this program! I have only been on it for 7 days, and already starting to see results!

    I am keen to continue, as the LISS workout is really working wonderfully for me. However, I am doing my LISS on the treadmill (my skin is very sensitive so can’t stand being out in the sun for too long!), but there are days when all the treadmills at the gym are taken! In that case, would you suggest that I get on the elliptical or the static cycle?

    Also, I have an upcoming overseas trip where I will be quarantined for two weeks there, then two weeks once I fly back home. Since I will not be able to leave the hotel room, are there any LISS workouts that I could do within a confined space? (I’m thinking jump ropes would be too loud)

    Cheers, thank you! :)

    1. Hey lovely,

      I am so glad that you are enjoying The Program! :)

      I suggest that, while you can walk outside, do the walks in the evening when it’s not too hot, and when all the treadmills are taken. :)

      I don’t think the elliptical will really cause bulkiness, but it won’t slim down your legs like running and walking will. The pushing down motion means you engage your quads more so it will build more muscle here.
      But it’s not the style of workout that will necessarily cause bulkiness.
      So feel free to try it out and see how it works for you.

      Here are the links to Rachael’s 2 amazing indoor cardio workouts that you can use as a substitute.
      Have in mind that these are just a temporary solution, and won’t show results as fast as walking would.
      But it is way better to practice these than none! :)


      Hope this helped! xx


  5. Hi Rachael,
    I’ve been taking your advice and doing fasted power walks 5-6 times a day as well as resistance training during the week. It’s been about 3 weeks, and I’ve already started seeing changes! Thank you<3 My only question is; I've been following this blog and making sure that when I power walk or do resistance training, my heart is in the right zone. But I started noticing in my third week that my heart no longer stays in the same zone when nothing changed with my power walks! It went from zone 2(as it should be), to zone 1 now. Could it be that my heart got used to the speed/pace? The same thing with resistance training, I went from zone 4 now to zone 3. Is my heart building tolerance? If this is the case for both power walking and resistance training, what can I do to ensure that I CONTINUE to stay in the fat burning zone? PLEASE HELP :( I get so discouraged seeing my heart bpm now and seeing that it is no longer in that fat burning category when my body is still working hard/even tired now. Thank you!!<3

    1. Hi, lovely<3

      Thanks for reaching out! :)

      I have some good news-your overall shape is getting better so it's not as difficult for you as it used to be and your heart doesn't have to "pump" as much :).

      You're becoming stronger!

      You can try walking a bit faster to get to the desired heart rate zone and add some light ankle weights for the resistance training possibly!

      Please let me know if there's anything else I can help you with!


  6. Hi Rachael,
    I love your program, and thank you so much for putting this together :)
    You mention that the heart rate should be at zone 3 while running, however, my heart rate always ends up at the extreme zone, zone 5, for most of my running time. I run at an average pace of 8.7 km/h, and I’m afraid that if I slow down to keep my heart rate at zone 3, then it is not going to be at a pace that you recommend. Do you have any suggestion for this situation?
    Thank you!

    1. Hey lovely,

      I am happy that you are enjoying your fitness journey! :)

      It is better that you listen to your body and take it easy – it is more important to get in the right zone in terms of your heart than to run fast.
      When you get used to this and your body starts to feel comfortable with running you can start working on your pace. xx


  7. Hello,
    I started the program a week ago and am already seeming amazing results. My body type is endomorph. I am doing a fasted cardio 60-90 minute power walk each morning, resistance training 4 times a week (doing the 3 recommended workouts as well as the fourth booty video) and doing another afternoon walk instead of a run because I did find running was bulking me up. My question is…is it ok to still take walks on the recommended “rest day”?
    Thank you.

    1. Hey lovely,
      That’s great! I’m soo happy to hear you’re already seeing results! :)
      And as for your question, that really depends on how you feel. If you feel like you would enjoy a good walk, then go for it! But if you feel like your body could use a bit of rest, feel free to rest :)
      Let me know if you have any other questions! xx

  8. Hi, I really want to slim down my hips and would really like for my butt to be smaller, I’m following the programme but just wondering if there is any exercise I should be avoiding or doing more of? Thank you!

    1. Hey lovely,
      If you want to slim down your hips and butt, just avoid additional booty workouts from the program. That will do the trick :)
      Let me know if you have any other questions! xx

  9. Hi Rachel,
    I have this question; with a pretty busy school schedule (and with a lot of homework, so I am not active for most of the day) it’s a challenge to fit exercise into my daily routine. This has also made it harder to stay motivated to start; as a result I’ve been less active, which has left me feeling horrible both physically and mentally. It’s been very difficult to find the balance, and I was wondering if you had any suggestions? If I’m in my mid-teens, how much exercise would you recommend would be enough to either maintain my weight (or slim down a bit) each day, and which type of exercise is best?
    Also, I can’t thank you enough for all the tremendously helpful information I’ve come across on this blog so far – it has changed my perspective and has boosted my motivation to make good choices concerning my health.
    Thank you in advance!
    – C. M.

    1. Hi lovely,
      I know how challenging it is to stick to a workout routine when you are so busy!
      If you are a teenager and your body is still developing, it is best that you consult with your parents and your primary care doctor in order to figure out the best nutrition and exercises for you.
      Good luck! Xx

  10. Thank you so much for the reply but my main question was what is the recommendation on what to eat after a cardio workout and prior to a walk if my workout is done fasted, it’s too much for me to walk fasted still afterwards. Thanks again!

  11. I do barre blend or lifting workouts early in the morning, fasted, before my kids wake up. Once my husband is up with the kids I go for a long walk but I feel in between those two things I need to fuel my body. What do you recommend having in between?

    1. Hi lovely <3
      I don’t know whether you know this, but Rachael is not lifting (she used to do it and she didn't like the changes to her body, you can learn more about it here so she is all for body-weight exercises because she prefers a leaner look. But if you love the way your body looks – go for it! As for barre, if the session includes lots of squat-like elements, you can also expect your legs to bulk up since it will activate your quads to a great extent.
      As for your question, I personally think that two activities a day is enough but in general, if you are looking for a way to mix it up or substitute the barre/lifting on some days, you can do some HIIT or go for a run.
      I hope this helps!

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