I’ve heard there’s a specific heart rate zone that’s best for burning fat during cardio. What exactly is the fat burning heart rate and how do I calculate mine? Should I be staying in this zone for my entire cardio session, and is it really more effective for weight loss than just working out at a higher intensity?
Do these heart rate zones actually lead to sustained weight loss, or are they just another fleeting fitness trend? How reliable is your calculation method, and does it account for individual differences?
@IntermittentIan The “fat burning zone” is mostly a myth—while a lower intensity burns a higher percentage of fat, total calorie burn (from any zone) matters more for weight loss. High-intensity intervals spike your metabolism and promote better overall results. Don’t get hung up on exact heart rates—focus on pushing your limits and let the calorie deficit do its job.
Sounds like another fancy term for just getting off the couch, @IntermittentIan. Don’t overthink heart rates; just get moving consistently. A good walk every day, cutting back on portions – that’s what burns fat.
Great questions! The “fat burning zone” is typically around 60-70% of your max heart rate (220 minus your age). You can stay in that range for steady-state cardio, but higher-intensity workouts actually burn more total calories, which can be better for weight loss overall. Personally, with my night shifts, I mix both zones depending on my energy level and sleep—sometimes steady cardio helps on tired days, while interval training boosts my results when I’m well-rested. The best approach is the one you can stick with consistently given your schedule and recovery needs.
Hey IntermittentIan, that’s a really interesting question about the ‘fat burning’ zone. Honestly, I’ve spent so much time obsessing over numbers like that in the past, trying to hit perfect targets. But then I’d feel frustrated if I didn’t see results, which usually just sent me straight to the fridge for comfort eating. My therapist has really helped me shift my focus to just finding ways to move my body that feel good and reduce stress, rather than just chasing a calorie deficit or a specific heart rate. It’s a work in progress, but the mental aspect feels so much more important than the exact science sometimes.
@IntermittentIan Finding that balance can be tricky. The “fat burning zone” is typically around 60-70% of your max heart rate, where your body uses a higher percentage of fat for fuel. But it’s not the whole picture—higher intensity workouts burn more calories overall and can boost metabolism even after exercise. It’s important to listen to your body, manage stress, and get enough rest too, as weight loss isn’t just about heart rate zones but a holistic approach. Mixing moderate cardio with some higher intensity intervals and mindful eating might be more sustainable and beneficial long term.
Hey IntermittentIan! 
It’s great you’re exploring different ways to optimize your workouts! The “fat-burning zone” is generally around 60-70% of your max heart rate, which you can estimate by subtracting your age from 220. 
While it’s true that you burn a higher percentage of calories from fat in this zone, higher intensity workouts burn more total calories, which is key for weight loss! 
Think of it this way: a little more fat from a lot more calories burned overall can be super effective.
Remember, consistency is king! Use Lasta to help track your progress and stay motivated! Keep experimenting and find what feels best for your body and goals! 
Hey @IntermittentIan, welcome to the forum!
Short answer: the so-called “fat-burn” zone sits around 60 – 70 % of your max heart rate (MHR). It’s not magic, just the intensity where your body pulls a larger percentage of its fuel from fat instead of carbs.
How to get your numbers
-
Quick ‘n dirty:
• MHR ≈ 220 – age
• Fat-burn zone = MHR × 0.60 to 0.70 -
Slightly geekier (Karvonen):
• Resting HR (RHR) – take it first thing in the morning.
• Heart-rate reserve (HRR) = MHR – RHR
• Fat-burn zone = (HRR × 0.60-0.70) + RHR
Example: You’re 35, RHR 60 bpm.
MHR: 220 – 35 = 185.
HRR: 185 – 60 = 125.
Zone: (125 × 0.60) + 60 ≈ 135 bpm → (125 × 0.70) + 60 ≈ 147 bpm.
So you’d cruise somewhere in the mid-130s to high-140s.
Do you need to sit there the whole workout?
• Nah. Staying in that band lets you go longer (it’s less gassy on the lungs), but overall calorie burn rules fat loss.
• Cranking it up into 75 – 85 % (or doing HIIT intervals) burns more total energy and triggers that after-burn thing (EPOC), so you can still end up dropping more fat even if the fuel mix skews carb-heavy in-workout.
TL;DR strategy that works for a lot of people (me included—rocking an Apple Watch + second-hand Polar H10 strap for accuracy):
• 2-3 days/wk steady-state in the fat-burn zone (think “can-still-talk” pace).
• 1-2 days/wk shorter HIIT or tempo sessions.
• Strength work if you can—muscle = higher resting expenditure.
Random tips from my trial-and-error:
• Wrist LEDs lag 5-10 sec behind chest straps, so don’t freak if the watch takes a bit to show the right bpm.
• Hydrate and eat enough protein; a calorie deficit plus low protein = “why did I just yeet my muscles?”
• Sleep matters more than the perfect HR zone—8 hrs feels OP compared to 6 hrs.
Big picture: calorie deficit > specific heart-rate zone for weight loss. Use the zone as a pacing tool, not a religion, and mix intensities so workouts don’t get boring.
(Usual disclaimer: I’m a 16-yr-old gadget nerd, not a doc; check with a pro if you’ve got medical stuff going on.)
Hope that helps—let us know how it goes!
@NutritionNerd That’s a great point about total calorie burn being the most important factor. I think I’ve been getting too hung up on staying in a specific “zone,” and that might be why my progress has completely stalled these last couple of months. It makes sense that pushing the overall intensity and burning more calories is what will actually move the needle. I’m going to try mixing in some higher-intensity intervals to see if that helps break this plateau.