Lower average heart rate when dieting - is that normal?

[ScubaAlex]

I got my fitbit and Pulsar heart rate monitor that I sync with digifit for Christmas and have been pretty good at wearing both every day and especially when I work out.  I'm 44 and in pretty good shape, working out almost every day.  My heart rate for cardio classes like a spin classes used to average around 164 bpm with peaks around 175 bpm.  I started to go on a diet a few weeks ago as I need to loose a few pounds (was 142lbs and trying to get down to 135lbs) and therefore eating around 1000 cals/day.  Since then, i've noticed a considerable drop in my average heart rate down to 150 bpm with my high being 165! I feel like I'm exerting myself and putting the same amount of energy in but for some reason I can't get my heart rate up there and disappointly don't burn as many calories.

I'm not sure what else changed in my routine besides eating less and not drinking as much alcohol so I was wondering if that contributed to lowering one's heart rate.

thanks!

[Colinm39]

@ScubaAlexI'm no expert and I trust those more expert in this field will comment.

I was on the understanding that eating less than 1200 calories/day would make you body go into "save" mode to prepare for a lack of food, and conserve, therefore slower metabolism, and possibly slower heart rate.

As I posted, I'm no expert and cannot recommend, and can only quote from those in the Fitbit Forums over the last 2 years.  Also, this link Read this but I'm sure you would have studied and discussed all of this with the Fitness programme you are on.

Keep us posted....

[Spang]

I am 65 and since I lost 100 plus pounds and got into cycling my pulse rate resting is 44. When I have been in the hospital they panic as my resting rate is 35. When I take a stress test they can not get my rate up to 132. It will go up there if I jog but they want walking.  With the heart rate monitor on when riding I have been able to get to about 135 for a bit and then it goes back down. I think that as you lose weight and get fit your heart does not have to work as hard and is more efficient.

[SunsetRunner · Accepted solution]

As your fitness improves your resting and working heart rate will go down as your body is becoming more efficient.

[ScubaAlex]

That is what I figured but I was surprised to see it change by such a noticeable difference and it seemed to be a pretty quick change.

[ScubaAlex]

Unfortunately in order to loose weight I have to eat around 1000 calories.  Calorie consumer when you get older is definitely not as high as when you're younger, and short of going to the gym, during the day I rarely get to 5k steps as I work in a small office. So my recommended normal intake is 1600-1800 meaning to loose weight I need to be around 1000-1200.

the interesting thing is that I didn't eat that much more before I noticed the change in my hear rate while excercising. It litteraly dropped an average of 15-20bmp over an hour work out in the span of a week.

-Alexandra

[Heybales]

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@ScubaAlex wrote:

Unfortunately in order to loose weight I have to eat around 1000 calories.  Calorie consumer when you get older is definitely not as high as when you're younger, and short of going to the gym, during the day I rarely get to 5k steps as I work in a small office. So my recommended normal intake is 1600-1800 meaning to loose weight I need to be around 1000-1200.

the interesting thing is that I didn't eat that much more before I noticed the change in my hear rate while excercising. It litteraly dropped an average of 15-20bmp over an hour work out in the span of a week.

-Alexandra

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Not true, you merely need to eat less than you burn.

And you can lose 1 lb weekly and therefore eat 1100-1300 if you still have 20 lbs to lose.

If 10 lbs or less, 1/2 lb weekly is more reasonable.

And it sounds like on workout days it should be awhole lot more.

Of course now with weaker body you burn less in your workout.

And you are correct, you did not improve your fitness level overnight like suggested with a big drop in HR immediately on changing diet.

One reason, you aren't getting enough carbs in your diet now to put in that effort.

Also, your muscles are weaker than normal likely, your ability to recover is impared when you go on a diet, so if you don't change your workouts to lighten up in frequency allowing repair, your body will force lightening up in intensity because they are just tired.

Neat ability the body has to adapt, huh.

Oh, better indicator of improvement in fitness is not during the workout but your resting HR. When that lowers in the morning after rest day, that's good indicator.

During the workout the indicator is hitting the same pace and effort, but the HR is lower - that's improved fitness during the workout.

[slysam]

As mentioned, heart rate will decrease with fitness improvements for a lot of people. But also, if you are having to eat very low calorie diet to lose weight... It makes me wonder whether all is fine with your hormones. For example, underactive thyroid will also cause a slower heart rate and lower body temperature (these are among the common symtoms). Sometimes very low calorie diets and a lot of cardio can apparently be a factor leading to underactive thyroid. If you have insurance, it might be good to have that looked at. But that is more a lower resting heart rate and lower heart rate in general throughout the day, I am not sure it is so much the exertion heart rate. Likely a 10bpm decrease in workout maximum sounds like a fitness improvement. 

[Spang]

There is a trick to balancing eating and exercise. You have to take your time losing weight, 1 to 2 lbs a week male. I have lost 42lbs in 32 days but that is not recommended. I find now that I have to have enough carbs with protein backing on work outs, cycling 1 to 3 hours, to keep my body going. If I do not have enough carbs my muscles are attacked and I bonk, lose too much sugar in the system. This leaves me without any energy. When I do it right an 8 ounce glass of choclate 2% or Skim milk is great for recovery.  I have also found that here in Texas that the summer is better with dill pickle juice.

[Mary]

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@ScubaAlex wrote:

That is what I figured but I was surprised to see it change by such a noticeable difference and it seemed to be a pretty quick change.

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Your high HR in spin class dropped 10 beats in 4 months?  I think that sounds normal.  The heart adapts quickly when you haven't been doing any cardio and then you start.  Your calorie or carb level didn't do it.  It's also possible your HRM is missing more beats than when it was new.  

[josephz2va]

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@Spang wrote:

I am 65 and since I lost 100 plus pounds and got into cycling my pulse rate resting is 44. When I have been in the hospital they panic as my resting rate is 35. When I take a stress test they can not get my rate up to 132. It will go up there if I jog but they want walking.  With the heart rate monitor on when riding I have been able to get to about 135 for a bit and then it goes back down. I think that as you lose weight and get fit your heart does not have to work as hard and is more efficient.

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If your heart rate is 35 BPM, you're in danger. 60 and below is a diagnosis for possible 

Bradycardia a life threatening symptom where the heart isn't having enough blood flow.

[Heybales]

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@ScubaAlex wrote:

I got my fitbit and Pulsar heart rate monitor that I sync with digifit for Christmas and have been pretty good at wearing both every day and especially when I work out.  I'm 44 and in pretty good shape, working out almost every day.  My heart rate for cardio classes like a spin classes used to average around 164 bpm with peaks around 175 bpm.  I started to go on a diet a few weeks ago as I need to loose a few pounds (was 142lbs and trying to get down to 135lbs) and therefore eating around 1000 cals/day.  Since then, i've noticed a considerable drop in my average heart rate down to 150 bpm with my high being 165! I feel like I'm exerting myself and putting the same amount of energy in but for some reason I can't get my heart rate up there and disappointly don't burn as many calories.

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Already in good shape, working out almost daily.

Got HRM in Dec to actually watch the HR and see stats.

Start a diet a few weeks ago creating a deficit of sounds like pretty good sized. 1000 calories daily with almost daily exercise?

Since that time few weeks ago, the avg HR has dropped 14 bpm and max HR 10 bpm you used to be able to reach in spin class.

Just wanted to lay out the facts that you mentioned, please correct me where wrong. Because sudden increase in fitness isn't going to happen starting a diet. Nor after already being fit and exercising daily.

Actually, the other issue besides lack of carbs, is the fact you didn't lighten up on your exercise routine.

When you go in a diet, especially a big deficit it sounds like you took, recovery is impaired.

There is Frequency, Intensity, and Duration to exercise. When you go in a diet, if you don't purposely back off one of those enough, the body will back off intensity automatically.

You just can't push as hard on muscles that aren't recovered. Especially when not eating as much, and I'm betting that includes carbs.

If you had some means of actually seeing your resistance on the spin bike, like you could see incline or pace on a treadmill, I'd bet you'd find it is less than before too.

The lower HR is just the manifestation of that.

You might try to purposely not go as hard as you can each day - that's counter productive. Make every other day a recovery day, walk, do slow ride, swim, ect. You'll find with muscles that can actually repair fully, you can make the hard days harder. Though a big deficit is still going to impact that.

[Spang]

That has only been when I have been in the hospital and under meds. The nurses find that I am ok and have fun with it. My normal laying in be rest rate is 44 and then the sitting sometime walk in 55. I was able to get my heart rate to 143 on the bike the other day on a cat 5 hill. The average was 47% of the ride in max fat burn and 41% of the ride in elevated intensity. I do watch and make sure all is OK. If I had 36 sitting at home I would go to the EM.

[Spang]

To add a bit. There is a correlation to HR and both fat run and fitness. Both are variable based on the individual. There is one level that allows for the burning of fat more than onther areas. The thing that I have found is that is takes me about 20 min. to get to fat burn and I will stay there until 60 min. of exercise. If I have not eaten and made sure my electrolyte are OK I will then start burning muscle and bonking.

[CandyElektra]

My heart rate jumps to about 140bpm just standing still brushing my teeth. As soon as I lay down and put my feet up on a pillow (and rest for 10 minutes not moving) my resting rate sits at about 95-100. The crazy thing is that when I'm doing cardio to the state of being "winded" but not dizzy, my heart rate will actually drop from the standing/brushing teeth average to around 130bpm. I have tested this anomoly more than a few times. I think my body is rejecting the human expectations and ...it's just not normal. My google doctorate in medicine hints towards "POTS" but who knows. It makes it hard to stay active...or even standing. I have to tie a sock AROUND my calf/shins JUST to stand and do 5 minutes of laundry without bruises forming on my legs. Insane! I'm only 33!

[TandemWalker]

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@josephz2va wrote:

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@Spang wrote:

I am 65 and since I lost 100 plus pounds and got into cycling my pulse rate resting is 44. When I have been in the hospital they panic as my resting rate is 35. When I take a stress test they can not get my rate up to 132. It will go up there if I jog but they want walking.  With the heart rate monitor on when riding I have been able to get to about 135 for a bit and then it goes back down. I think that as you lose weight and get fit your heart does not have to work as hard and is more efficient.

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If your heart rate is 35 BPM, you're in danger. 60 and below is a diagnosis for possible 

Bradycardia a life threatening symptom where the heart isn't having enough blood flow.

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Not true. A normal resting heart rate for adults ranges from 60 to 100 beats a minute. A lower heart rate at rest generally implies more efficient heart function and better cardiovascular fitness. For example, a well-trained athlete might have a normal resting heart rate closer to 40 beats a minute.

[Spang]

The 35 rate is only when I am in the hospital with drugs in me. The normal sleep rate is 45 and waking rate 55. Yestrday I rode 20 miles on my bicycle with 10 of that into the wind and my average HR was 102 with nothing over 139. two weeks a go pushing hard I was able to get my HR upto 155 for a very short time.

[TandemWalker]

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@Spang wrote:

The 35 rate is only when I am in the hospital with drugs in me. The normal sleep rate is 45 and waking rate 55. Yestrday I rode 20 miles on my bicycle with 10 of that into the wind and my average HR was 102 with nothing over 139. two weeks a go pushing hard I was able to get my HR upto 155 for a very short time.

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Yes, these more or less mirror mine.

[Spang]

I believe that the reason mine are like they are -- is 20 years Army and PT with lots of 5 mile runs. Then when out of the military I started riding a bicycle most of the time 5 times a week for at lest 15 miles each ride. Now that I am teaching I ride once or twice a week 15 to 30 miles each time and in the summer 5 to 6 days 13 to 40 miles. I believe this has strengthened my heart and the cause of the low rate. My cardiologist says that that is the the reason that when I had a 95%+ blockage that he was able to find it before it ruptured -- the capillaries carried the oxygen around the blockage allowing the body to still work.

[Heybales]

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@Spang wrote:

I believe that the reason mine are like they are -- is 20 years Army and PT with lots of 5 mile runs. Then when out of the military I started riding a bicycle most of the time 5 times a week for at lest 15 miles each ride. Now that I am teaching I ride once or twice a week 15 to 30 miles each time and in the summer 5 to 6 days 13 to 40 miles. I believe this has strengthened my heart and the cause of the low rate. My cardiologist says that that is the the reason that when I had a 95%+ blockage that he was able to find it before it ruptured -- the capillaries carried the oxygen around the blockage allowing the body to still work.

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And I'll bet if you could have had your HRmax tested back then and now, you are no where near the 220-age downgrade in HRmax.

Besides which, sounds like you have a diesel heart anyway from those other stats, so formula is likely way off on 2 counts.