Heart Rate & 'Fat Burn' Zones: The Truth About What You Really Need To Know

Fit with Frank
Jul 1
4 min read

Updated: Jul 8

Had a client stop mid-class to show me their apple watch and ask me if they were 'in the fat burning zone' and it got me thinking...

'How dare you stop squatting to ask me a question? Get down and gimme 10 burpees as for wasting time...' 😜

ha-ha, I jest, obviously, (no one needs burpees in their life) but it did get me thinking about how to answer this appropriately, so here we are with my best attempt to help you understand the 'zones' on your watches. and how they may or may not be appropriate for your fitness training right now.

Hope it helps....

🎧 First things first: Give the podcast a listen

Myself and Katie Bulmer-Cooke host a weekly fitness podcast and dedicated this episode to discussing everything with as much detail and honesty as we can.

Prefer to read? Keep scrolling...

📊 What Are Heart Rate Zones, Really?

Think of your heart rate zones like gears in a car, the higher the gear the faster you move.

Zone 1: Sunday stroll
Zone 2: Brisk walk or easy jog, can still talk without wheezing
Zone 3: Puffing a bit
Zone 4: Starting to sweat
Zone 5: Can’t talk, can’t think, definitely not smiling

Your Apple Watch or Fitbit guesses which zone you’re in based on how fast your heart’s beating. These zones can be useful for pacing yourself, building fitness safely, and sometimes just making things a bit more interesting.

But, chasing a particular zone won't magically burn fat or make you fitter overnight. Sorry.

🔥 What About the "Fat Burn Zone"?

Ah yes, the old chestnut. The fat burn zone is where your body uses a higher percentage of fat for fuel. That usually happens in lower intensity efforts (like Zone 2).

But here’s the kicker: Burning a higher percentage of fat doesn’t mean you're burning the most calories overall.

To put it bluntly:

You’ll burn a bigger slice of a smaller cake.

If you go a bit harder, you might burn less fat as a percentage, but more calories overall, including fat.

So don’t overthink it. All zones burn fat, and the best one for you is the one that gets you moving consistently and feels doable.

❤️ Is It Even Accurate?

Not really.

Those zones are based on a rough formula (usually 220 minus your age).
Your wearable’s heart rate monitor can be out by 10–15 beats, especially if it’s on your wrist and you're flailing around.
Chest straps are more accurate, but let’s be honest, not all of us are strapping up for a walk.

Moral of the story? Take it with a pinch of salt. Zones are a guide, not gospel.

🟢 So... Should You Bother With Zones?

Here’s my honest take:

Zones can be motivating if you like a target to aim for.
They can be informative if you’re training for something specific (like a 10K or a comeback from the sofa).
But they’re not essential for most over 40s who just want to move more, feel good, and keep joints working.

If chasing Zone 2 helps you get out the door, go for it. If it stresses you out or makes you feel like you’re failing, bin it.

Your body doesn’t care what zone your watch says you’re in. It cares that you’re showing up. Day by day, step by step.

🪜 Want to Test Your Fitness at Home?

Now we’re talking! If you’re curious about how fit you are, or need a baseline to test yourself from, I’ve got a simple way to do it at home right now, No Laboratory. No Lycra. Just a step and a stopwatch.

All you need is a low step, a timer, and a bit of gusto. You step up and down for 3 minutes, then count your heart rate for one minute afterwards. The lower your heart rate is afterwards, the fitter you’re getting.

It’s not NHS-approved or scientifically perfect, but it’s quick, free, and gets you moving. And that's what counts.

👉 How it works:

Step up and down at a steady pace for 3 minutes.
Rest for 60 seconds and take note of your heart rate (use watch or manually check)
Compare your result to the benchmarks below
Retest every few weeks to track your progress!

🧠 Fitness Level Benchmarks (1 Minute Recovery Heart Rate):

Men (Age 40+)•

< 90 bpm – Excellent

90–100 bpm – Good

101–110 bpm – Average

111–120 bpm – Fair

> 120 bpm – Needs improvement

Women (Age 40+)•

< 96 bpm – Excellent

• 96–105 bpm – Good

• 106–115 bpm – Average

• 116–125 bpm – Fair

• > 125 bpm – Needs improvement

⚠️ Don’t worry where you’re starting from, just write it down and aim to beat your own score next time.

👋 Final Word From Me

Whether you're stepping, walking, or just dancing around the kitchen, understanding

Heart rate zones can be a helpful nudge, but they’re certainly not magic by any means.

If you're moving regularly, breathing a bit heavier than usual, and smiling now and again, you're in the right zone.

So keep it going, and know you're doing better than everyone else sitting on their sofas right now.

Catch you next week :)

Frank

Your Personal Trainer / Zone 1 Specialist

🧩 PS: Want help making this all make sense in real life?

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