xfimpg

Hi

I've done some searching and I've seen a lot of discussions on cycling and weight loss, but I haven't found my answer yet so here's the question.

If I rely on my Polar watch instructions, they advise that there is a fat burning zone between 55-75% of our cardiovascular capacity.

As opposed to riding in the 76% to 85% range for example, is a lower heart rate really conducive to fat burning?
Has anyone ever tested this out? Any first-hand experience to speak of?

gfactor

It means that your energy source is more fat than carbohydrates. It does not mean you'll lose more weight in that zone.

xfimpg

If fat is what you want to lose, which you have in excess, doesn't that mean you will lose more weight as you are burning fat?

pacificaslim

The fat burning zone is the zone at which fat is the highest percentage of fuel your body is using. Many people misinterpret this to mean it's where the most fat is burned. But this isn't correct. If your goal is total amount of fat burned, that will continue to rise as you move up out of the "fat burning zone" and go faster/harder.

xfimpg

Now this is interesting because my Polar tells me that at an avg. heart rate of 85%, 30% of my calories are from fat, as opposed to an avg. of 70%, it advises me that 50% of my calories are from fat.

Really interested to hear testimony from anyone who's experience supports either of these theories.

pacificaslim

Think of what your Polar is telling you this way. Over a given period of time:

70% of Max HR: 500 calories from fat, 500 other (i.e. 50% from fat)
85% of Max HR: 800 calories from fat, 1850 from other (i.e. 30% from fat)

So at 85% effort, even though the percentage of fat used was only 30%, the amount of fat burned was higher (and you lost a lot more weight overall, too).

ericm979

Lower intensity riding can burn more calories but only because you can do more of it without getting too tired. If you are limited by time then higher intensity riding will burn more calories.

It doesn't make much difference for weight loss where the calories come from. If you burn glycogen (carbohydrate) calories they still have to come from somewhere. If you are eating enough to replenish what you use, they'll come from food. Otherwise, they come from stored calories in the body, i.e. body fat.

chinarider

Right, but I think you overestimate the difference in total calorie burn for the 2 intensities (although that does help illustrate the principle). It might help to think about it this way. If your 70% effort is 13 mph and you ride for 1 hr, you'll burn ~400-to 500 calories, maybe half of which are from fat. If your 85% effort is 17mph and you go for 1 hr, you'll burn ~ 700 to 800 calories. If 30% are from fat, you will have burned about the same amount of fat, but more total calories. And for weight loss, it's total calories that really matter.

In addition, while there is some disagreement on this, studies seem to indicate that more intense exercise results in greater afterburn.

gregf83 

Fat oxidation peaks at around 65% of VO2Max. At higher intensities both the % and amount of fat burned decreases. So the Polar data sounds reasonable. You'll burn more calories at higher intensity but they will coming from stored glycogen.

chasm54

^^This. And the trouble with burning the extra calories but taking them from stored glycogen is twofold. First, until you're in good shape you won't be able to sustain that intensity of effort for very long, whereas staying in the fat-burning zone you should be able to keep going for a long time. So if you have the time, staying in the "fat-burning zone" may well result in your burning more calories simply because you'll be exercising longer. Second, the glycogen stores have to be replaced. If you deplete them, your body will demand carbs when you finish exercising and this can result in your eating more. Burning mainly fat does not result in such intense pressure to eat, because there is not the same physiological imperative to replace what has been burned.

So, if you want to lose weight and you have time to do extensive, as opposed to intensive, workouts, that is probably the way to go. If you want to both lose weight and get fit as fast as possible, do both - some extensive sessions at c.60% and some interval training on other days.

pacificaslim

Related article from Velonews twitter link: https://velonews.competitor.com/2010/...medium=twitter

gfactor

It's simplest to just think of weight loss as calories input vs. calories output.

xfimpg

thanks for posting.

Don in Austin

Polar might be good hardware, but there training theories etc. are crap. They actually sell a hear monitor with software that claims to calculate your VO2 max by measuring your heatbeat while you are sitting still.
What a scam! Interestingly, you have to enter your age, level of physical activity etc. which is mostly where the VO2 max number comes from. I have also seen them quote the "220 - your age" method of determining your maximum heart rate -- a formula that has been thoroughly discredited.

Use your Polar device for direct measurements and disregard all their other crap.

It actually pretty hard to go wrong exercising full tilt boogie if you have no special medical problems and use common sense.

Don in Austin

kmac27

Lower intensity exercise for longer periods of time does not yield a leaner body compared to higher intensity workouts for shorter durations of time. This is because there are calories burned during a workout, but after the workout the body still is replenishing its stores. And higher intensity workouts yield longer after burns.

A half hour lactate threshold bout can leave one with an elevated metabolism for 1.5-3 hrs from my experience while long rides tend to last an hour to an hour and half. This is assuming that I am taking in nutrients during my workouts on both types of training.

chasm54

You're kidding. My standard loop takes two and a half hours. Four hours + would count as a long ride. An hour and a half would not qualify as extensive, low-intensity exercise as far as I am concerned.

And, of course, the increased efficacy of the higher-intensity session (which I don't dispute) depends on your being able to manage your calorie intake. And most people seems to find that more difficult when most of the calories burned have come from glycogen stores, which have to be replenished and that tends - ime - to encourage less controlled eating. Speaking for myself, I find that I am much more likely to lose weight while touring - four to six hours on the bike at moderate speeds, eating pretty much a normal diet - than when I'm "training" at higher intensities, which causes my appetite to markedly increase.

kandyredcoi

intervals: https://www.bicycling.com/training-nu...-fat-intervals

chasm54

Yeah, I know all that, and I agree. But look at the prominence given in that article to eating right, and therefore capitalising on the benefits of the calorie-intensive interval training. My argument is merely that most people will not maintain the discipline required in the face of the pressure to eat that is driven by workouts that burn mainly glycogen. Lower intensity, longer workouts burn mainly fat and do not result in such intense pressure to eat.

The correct answer is, of course, do both. But prescribing interval training as the principal route to weight loss for most people isn't going to be successful, imo.

kandyredcoi

understood, but you really need to do both to get great results, quickly, but if there is no rush...imho losing weight/burning fat can def still be achieved via intervals, if done right

tadawdy

You can't make someone who isn't even disciplined enough to do 45 minutes of cardio, or just doesn't/can't make extra time, to go out on a bike for a few hours. They want to come to the gym and get in and out with efficiency. If they're doing less than an hour of activity, you'd better make it count. This is one reason HIIT for the general population makes sense. It also makes sense for maintaining VO2 max, which influences fat metabolism at all levels of exertion, as one ages, though that isn't going to sell a lot of people for the short term.

If they aren't going to do LSD type rides, the question becomes not one of longer and slower vs. shorter and faster. It becomes short and slow vs. short and fast (puncuated). The choice is then pretty obvious.

I'd love for my clients to be able to go on 2+ hr rides each day, but it generally ain't happening. It is very different when dealing with people who lead truly inactive lives. Even getting them to walk places instead of driving can be big. One guy did walk 7 miles (round trip) to dinner the other night, which is progress.

Cycling is sometimes a little harder to implement, because it can seem foreign, dangerous, weird (lycra), there are many equipment issues, lack of equipment...

chasm54

I understand your problem. But it's asking a lot of any training, even interval training, to make much impact on someone's weight if they're only doing an hour or two a week and are sedentary the rest of the time. They'd better just eat a lot less, I'm afraid... and I guess you're going to tell me that plenty of them aren't disciplined enough to do that, either.

As for cycling, it has one big advantage for some people in that it offers the potential to get your cardio while commuting without using much time that wouldn't otherwise be spent in a car, on a suburban train or whatever. Efficient. But we're getting a bit off-topic..

Stig O'Tracy

There is a simple solution to that one, save your meals for after the ride. For my lunchtime and weekend morning rides, just a glass of water before, then a meal after. Also, for myself, I am bit less hungry after working out, and I don't like to eat before a workout.
Besides, depending on exercise alone for weight loss is a difficult road unless you can excercise a lot, and can resist the tempatation to increase calorie output.

chasm54

LOL, I can do that. But it isn't when to start, it's when to stop that is the problem!

And of course I agree that controlling input is the crucial thing. Very few of us can spend so much time exercising that we can eat whatever we like.

tadawdy

I don't disagree with you. Commuting saves some time, but it doesn't work for some people...those who have to get to multiple, distant locations for work, for example. As for volume of training, two hrs a week is a low estimate, and of course that wouldn't do much. I'm thinking of one client, in particular, who is in a Biggest Loser competition, and is therefore motivated to work hard. We have workouts 3x per week, and he does some form of dedicated cardio (often with intervals) on at least 3 other days. We're talking about 6 hrs total a week of dedicated exercise. That's about what he's able/willing to put in with his job and family. It's also enough to create a significant caloric deficit, but of course it has to be bolstered by dietary changes.

He has just recently been able to do this volume of work, and it's time to try increasing it. I'd like to get him cycling, since he's heavy and a mechanically poor runner, but he wasn't so receptive when I mentioned it before.

Lobs616

So for someone who is new to the sport and exercise in general and needs to lose about 50 pounds, what is the best method. Do I strive for riding for longer times at a slower speed, building up to going as fast as possible for as long as I can, or a form of interval training. I am finding this thread very interesting but am not sure what the conclusion is. Thanks