What if you burned 3500 calories in a day?

To even burn near 3,500 in 3-4 hours... it is extensive abuse to your body. I have to put my stationary bike on an incline of 20, and it is terribly hard to push the pedals. Then I go as much as I can for as long as I can. My *kitten* will hurt of course after an hour or so. Have to take a short break of walking around. To move my arms, I use Wii Active Heavy Boxing. I do both exercises together which will burn fat no joke but the result is extensive.

I don't think a normal person could do it. My calves are huge from power lifting with the thousands of squats I did. Let alone, someone might get bored to exercise that much in that certain amount of time.

I'm not sure how accurate MFP is when it comes to calories burned. This afternoon I walked 10.5 miles in 3hrs around the streets, which is 3.5mph and which MFP says I've burned 803 calories. However, according to MFP if I had hiked for 3hrs, I would have burned 1,267 calories.

To me walking is just in light shoes, on pavements and not carrying anything more than my phone and house keys, whereas I consider hiking to be in boots carrying a rucksack (not a very heavy one, just a waterproof, water and food) and out in the countryside. However, I built up much more a sweat walking 3.5mph for 3hrs, than I ever do hiking across the countryside.

When I'm out in the coutryside I try and drink about 300mls of water every hour and eat a cereal bar every couple of hours. A couple weeks back I hiked 20 miles in just under 9hrs and I gained 0.4lbs from the morning to the evening and yet my calories eaten were just under 1600! It didn't seem fair, but my weight is going down and my stamina is going up, so walking is working for me

Incidentally, according to MFP, I would have to walk for about 15hrs at 3mph to burn 3,500 calories or about 8.5hrs hiking, but I can't image I would burn all that in that time, 15hrs maybe

Thanks for that link. You're right, when I'm hiking I'm on uneven ground and yes there are hills, and stiles/fences to climb over. When walking it is generally flat and even, so yes I can see how hiking would burn more. It's just walking the streets is a bit boring compared to being out in the countryside with all the fresh air and distant views, so that is much more enjoyable and the miles slip by.

If I use the METs value for walking 2.8-3.2mph and apply it to a BMR of 1843 (Katch-Mcardle for 300lbs. and 50%BF), I estimate walking 8 mph burns around 1400 gross or 1000 net calories. Meaning 400 of the 1400 you would've burned sitting at home those hours.

https://sites.google.com/site/compendiumofphysicalactivities/Activity-Categories/walking

So, yeah, 3500 is not even in the ballpark.

Where did that even come from? If I put in walking 3mph for 160mins. (comes out to 8 miles at moderate pace) in MFP for me it spits out around 600 calories.

The link you posted, are those realistic numbers? May I ask how you calculate with them. I'm trying to find out how much calories I'd burn with for example swimming laps at various intensities. Thanks.

If an activity has a MET value of (for example) 3, it means you are burning calories at 3 times your basal expenditure rate. So if your BMR/RMR is 2000, that's an hourly rate of 83 calories (this doesn't account for sleepy time, it's just rough), so an activity level of 3 would mean you burn 3*83 -> 249 calories in total. Or (3-1) * 83 -> 166 calories above your BMR/RMR.

METs tables here.

https://sites.google.com/site/compendiumofphysicalactivities/Activity-Categories/water-activities

Like everything else involving calories, understand that there are error bars are on all the numbers! Forest, trees, etc. :drinker:

Cool! That's what I needed! Now I only need to determine my bmr properly. Does the BMR include the part about sedentary vs. active lifestyle? I would guess not as the energy expenditure due to sport is part of that.

No, because the body doesn't gain/lose on a 24-hour cycle. It's a continuum.

sorry but I failed to see the logic here...if you burned 3500 calories, it should be a pound right? either it's within 8 hours or 8 days?

People here say that it's not like you can do a marathon everyday... This is possible... check out Dean Karnazes who did 50 marathons in 50 days and have ran ultra distances up to 500 KM non stop. He isn't the only ultra runner to burn so many calories... there are people out there that run ultras and train for ultras. I myself have burn up to 6000 calories one go. You may or may not lose weight depending on consumption... but one thing I do know is that your body becomes built to adapt.

The "Hiking - cross country" in MFP is pretty weird, it's set as double the calories of the "Walking 2.5mph". Perhaps it's meant to be hiking at an incredible speed, or something. I usually just enter the Walking with the time, even though that's probably understating things.

The OP might have been talking about total calories burned in a day... according to MFP, my resting calories burned are about 2600, so getting to 3500 would only be another 900 calories from exercise. Which, with that hiking calibration, would be an hour and twenty minutes.

Even just on the face of it, as 3500 extra calories from exercise, it's not impossible. I don't know if I've ever done that much, but I got to 2800 on Tuesday, and I know that's not the most I've done.

I haven't read all of the posts but my garmin said I burned 3600 when I ran my first marathon. My weight was pretty much the same the next morning but by the end of the week I was down a few pounds.

on a related note, I also wonder what happens to those who fast like a week or longer. even your metabolism is slowing down on the fourth day, it's still burning right? so if you fast 7 days or a month, you should lose a lot of weight, too. Is this right?

Maybe. But humans potentially can go months without eating (varies by person of course) so if calories in and calories out were true, why are those people not dropping dead rather quickly? With all the "establish your TDEE, and eat at a deficit" advice you'd think that's exactly what would happen and it doesn't. Because of the low calorie bs I now have a very slow metabolism (it can be fixed over time) and I'm currently eating well under my TDEE (supposedly) and I am gaining weight (but not really getting physically bigger). I know what I eat, I know what I do, but a bunch of people will be quick to assert that I'm lazy, lack willpower, am not tracking accurately, not tracking everything, not weighing my food, blah blah blah. They can go fly a kite.

This is really interesting thanks for answering my question! Just so everyone know I dont plan on trying this it was a thought that came up during an 8 mile walk where I almost unintentionally burned that amount.

A few months ago I accidentally burned that many calories. I had an old, out-of-date map with an error on it, so an 11 mile hike in the mountains ended up being 21 miles. It was dark when we got back to the car and I was super sore (felt a lot like what I feel like after running a marathon), but I don't remember any weight changes. (TBH, I wasn't really paying attention since I'm on maintenance and I don't weigh myself very often.) I was careful to eat a crap ton of food for a couple of days to make up for it, though. I don't think a single major calorie burning session does that much, especially not immediately. It's really something that takes place more over time. You wouldn't see it right away, unless it was water weight changes or something.