Max amount of calories you should burn while exercising?

[cjchaps]

I'm a male, 6'0 tall, 200 pounds, and I was wondering what the maximum amount of calories I can burn without anything bad starting to happen with my body?
For instance, yesterday I used a machine at the gym and burned an estimated 750 calories. I assume that is a safe level of calories to burn in a single exercise session?

 

[yobarman]

personally, i dont think it matters. A lot of people can bike or jog a marathon pretty much forever. I used to play roller hockey until i was completely finished. My guess is you've only lost enough calories when you really can't work out anymore.

 

[Fausto]

Well, you won't do anything "bad" by exercising for long period of time. I'm a cyclist and it's not uncommon for me to do anywhere from 3-5 hours in the saddle on a weekend day...this is easily over 2500 calories. What will happen is that after enough time (usually about 1.5 hours) you will have used up all your body's glycogen stores. When this happens, your body will shift over to burning solely fat for energy. The problem with this, is that the process of extracting energy from fat is much slower that getting it from glycogen, so you start to feel lightheaded and weak because your bod can't supply energy to match your level of exertion (this is referred to as "bonking" by cyclists and others). The easy solution to this is to try to down about a pint of gatorate (or other energy drink) every hour and munch a Powerbar or two for every few hours of your workout.

Also remember to try to suck down a bunch of carbohydrates immediately after your workout to replenish your gycogen stores. Your body is much more efficient at refilling these immediately after a workout (the "glycogen window" is up to an hour after you stop the workout).

One other note: Clif bars are the bomb....taste like cookies. My faves are the apricot and mocha.

Cheers,
Fausto

 

[vi edit]

Unless you were on the machine for about ohhhh...3 hours I highly doubt you burned that many calories. I don't really trust the calorie counters on those machines.

250-300 would be a nice number to shoot for. Too bad that is negated by one 20 oz. soda or a candy bar

But, it's not the calories burned in the workout that make the difference, it's the muscle tone you gain while working out that rases your metabolism and ultimately increases the number of calories burned at rest that matters.

 

[Fausto]

<< But, it's not the calories burned in the workout that make the difference, it's the muscle tone you gain while working out that rases your metabolism and ultimately increases the number of calories burned at rest that matters. >>


This is only partially true. You will raise your BMR by gaining muscle mass and because your body is busy "rebuilding" tissue after a workout, but you will make a much larger difference in caloric expenditure via the aerobic output. Of course it all depends on how hard you're going during your workout, but 500-800 kcal in an hour is by no means an absurd number for moderate aerobic exercise (say heart rate at 60-80% of max). The more inefficient the workout (ie- running is much less efficient than cycling) the more you burn.

Theoretically, burning 500kcal per day for a week = 3500kcal which is what you need to burn to lose a pound of fat.

The increase in BMR thanks to daily workouts is more along the lines of 50-100 kcal per day...so 350-700 per week. Better than nothing, but still not nearly approaching what you burn aerobically.

Fausto

 

[vi edit]

Fausto1, your numbers just seem way high. Maybe my cross country coach was full of crap or something, but I don't think I came anywhere close to burning that many calories just from working out.

Also, I know there's a formula for figuring out how many calories muscle burns vs. fat and using that formula you could figure out your bodies caloric need per day based upon BMI. It's been years since I've had to figure that out though.

I guess personal expererience has proven to me that more muscle put on via weight lifting has kept me more trim than a moderate level of aerobic exercise. By moderate I mean 30 minutes a day, 3 or 4 days a week.

Everyone is different, and their bodies work in different ways. As always, YMMV.

 

[hevnsnt]

I have just started working out again.. And I have noticed that I am not losing any weight.. However I am shrinking.. I normally burn about 500-550 cal a workout (cardio) and then I lift for about a half an hour.. The biggest thing I have found is to cut off my morning Dr. Pepper.

 

[Fausto]

The numbers depend largely on how big you are, what you're doing and how hard you're doing it (that reads rather obscenely, doesn't it?). The rule of thumb for cycling (we're talking real cycling here, not a 5mph stroll in the park) is roughly 700kcal per hour assuming you're averaging around 16-18mph. You can add to this figure if you're going up and down hills.

The other difference in your view and mine is I'm assuming at least 60 min per day, 4-6 times per week. At 30x3-4days you are probably about even as far as aerobic vs raised BMR calories burned. The bottom line is that your body is like a bank: every kcal expended has to be recouped somewhere...either in food intake or by breaking down fat to restock the gylcogen stores. Any form of exertion will burn calories, but you can only do so much via increased BMR whereas you can burn thousands per day aerobically if you're so inclined. Riders in the Tour de France will consume something like 6000 calories per day and still lose a few pounds over the three weeks of the Tour. Granted this is an extreme example, but illustrates my point somewhat.

Fausto