# How many calories are you burning in 45 min workout?

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Posts: 108 Member
I know that is a very broad question. I am 5’6” around 62kg and doing a circuit class including weight training and boxing for 45min - it is a tough workout can anyone similar let me know how much they are burning? I don’t have a fit bit.
Would 300 calories be alright to eat back? Don’t want to overestimate

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• Posts: 32,763 Member
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I'm 5'5", around 62kg (mid 130s pounds), and a 45-minute spin class (best intensity I can sustain) usually runs in the 280-300 calorie range, so my guess is that 300 wouldn't be crazy wrong. Weighted workouts tend to feel harder than purer cardio for the same number of calories, so maybe a little high.
• Posts: 9,524 Member
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I once created an interval workout entry for myself, based on logging data for a long time very precisely and doing such workouts. And logging data for a long time without any workouts. Thus I have a fairly good idea what my TDEE for sedentary is and how much calories such workout would burn. We're about the same size and currently about the same weight. So that was easy to check.

If I enter 45 minutes I get 294kcal. However, this is for 45 minutes without any breaks. If you work out for say 50 seconds and then do a 10 second break during those 45 minutes then the calories would only account for a 37.5 minute workout, thus just over 250kcal.

You're welcome to create your own custom workout entry with this,

• Posts: 10,009 Member
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I think it would depend a lot on how much time you're spending weight training and how much time you're spending boxing. 45 minutes of boxing, depending on intensity and your fitness level, could easily be anywhere in the 300 to 600 kcal range. 45 mins of weight training, with reasonable recovery periods between lifts? Maybe 150?
• Posts: 108 Member
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Thanks all - I am just trying to figure out the maths. So if my calories to lose 0.2 kg a week is 1650 and my maintenance is 1930

If I eat at around 2000 on workout days I won’t gain any weight hopefully
• Posts: 8,934 Member
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250 to 300. Ann had it right.
• Posts: 610 Member
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Depends on intensity. 250 to 400. 5'3", 157 lbs, 43 yo.
• Posts: 67 Member
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I am 5ft 7in around 140 lbs and with a high intensity workout (I work out with a small group at a private gym for 45-60 min) and I tend to burn around 350-400 cals. I would invest in a HRM watch whenever possible.
• Posts: 9,524 Member
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alondrakar wrote: »
I am 5ft 7in around 140 lbs and with a high intensity workout (I work out with a small group at a private gym for 45-60 min) and I tend to burn around 350-400 cals. I would invest in a HRM watch whenever possible.

How do you determine this burn?
HRMs are not suitable for this kind of interval but only for steady state as they tend to overstate slower moments or breaks as your heartrate doesn't drop down the moment you stop an exercise. Plus, many (not all) women tend to have a higher than normal maxHR, and as a result such device will record far too high burns unless one knows one maxHR and changes the settings. I would guess though that most people are not fit enough to really determine it properly.
• Posts: 32,763 Member
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Heart rate monitor may be particularly bad for circuit training that involves weights, as described by OP. You have the heart rate lag issue with heart rate not tracking effort accurately during interval work (and the amount by which it's off might vary based on fitness, so hard to evaluate), but also the issue with HRMs being bad at handling strength training, especially overhead moves, because the pressure/strain raises heart rate in a way unrelated to the work being performed and the calories being burned).

The fitness trackers with HRM that know what exercise you're doing (because you tell them) have the theoretical potential to do a better estimating job algorithmically, but I haven't seen any reasonable demonstration that they take advantage of that potential.

And yes, age-estimated max heart rate being so often wrong is a factor, as well.

Don't get me wrong, I think fitness tracking devices can be useful for training (i.e., managing fitness efforts) and I even think a fitness tracker can be an advisory input to thinking about calorie estimates for intervals, but I wouldn't take its estimate as gospel.

Too many people trust an electronic device to be spot-on accurate, but it's important to understand their limitations for calorie estimates.

Oldies, but still goodies: