Have you ever stopped to think that there might be an upper-limit to human metabolism?
Basically a ‘ceiling rate’ at which we can burn through calories?
Probably not, but don’t worry… I did for you!
I’ve heard rumors of people eating well over 10,000 calories during a single cheat day, or even every day during a period of intense training.
This got me thinking… can an average human being actually burn 10,000 calories in a single day..and what would that day look like?
Fortunately, when looking for research on almost inhuman circumstances we can always turn to the military!
I was able to find research on the daily energy expenditure found in marines undergoing the Crucible exercise.
Now..the Crucible isn’t just some pumped up CrossFit Workout.
It’s not eve football Two-a-days.
In fact, this is how my contact into the marines described it:
Before it even started, we had to hike to our camp site. Carrying a loaded ILBE pack with about 80 pounds of gear, we hiked about four miles from the barracks to the site. We set up “tents”, which were in fact two ponchos strung together with sticks, and then the event began.
Wearing a fully loaded down flak jacket with bulletproof SAPI plates, my platoon was made to run (at full speed) everywhere throughout the mountains with a daypack full of field and hygiene gear, as well as enough food for the event. If we weren’t running, our drill instructors were making us work out until we vomited, and if we weren’t throwing up, we were running to the next training exercise. The exercises included rope climbing, scaling walls, lifting other recruits over walls and into buildings, and a lot of PT involving our own body weight.
Other events included pugil stick matches, 5 minute boxing rounds, and lots and lots of pushups.
And, this is where it gets really fun…
This continues on for the ENTIRE day and night. In fact, it’s a 50 some-odd hour exercise with almost NO sleep.
The results of this research were very similar to what was found by other counties studying their military personal in extreme circumstances…
In extreme situations the body seems to top out at around 40 Calories per pound of body weight per day.
Obviously body composition, muscle mass etc come into play a bit here, but for a 200 pound man athletic man (think marine recruit), this means a daily energy expenditure of around 8,000 Calories. (For a 150 Pound women it would be about 6,000 Calories per day)
So what does this teach us?
Well most importantly, it shows us that unless you are a very large person to begin with, even the most INTENSE hour long workout is not going to make us burn 8,000 Calories in a day.
In fact, to burn bur 10,000 Calories in a day you would need to take part in an INTENSE 24 hour long workout, and that’s just not very realistic.
So bottom line –
It is actually difficult to eat 10,000 calories in a day (I’ve tried) but if you do, be aware, it’s going to take you a more than a couple hard workouts to burn it all off.