lessthanhalf
GLP-1 Specialist
Research has been done on this , and in the short term in ultramarathons or cycling competitions, it can be as high as 10000 kcal/day. There was a study done in the race across the USA a 140 day race where energy expenditure started as high as 6000/day but it cannot be sustained long term and slowly drops to 2.5 times basal metabolic rate or about 4500 kcal/day, which is the same as the peak growth period in pregnancy, and is possibly limited by calorie intake and gut absorption, tissue repair and metabolic processes having limits. So the second law of thermodynamics is not being broken and someone will consume more calories walking 40km than 30 km, but the extra calories if it exceeds this limit will most likely be recovered over the next few days by being too tired to cover the 30km per day.
The process involved in limiting energy expenditure in low calorie intake situations is not going to be exactly the same, but it does indicate the body does have adaptive mechanisms to control energy expenditure over time. During weight loss energy expenditure is nowhere near this hard limit, but presumably the body can set different limits in different physiological states.
The process involved in limiting energy expenditure in low calorie intake situations is not going to be exactly the same, but it does indicate the body does have adaptive mechanisms to control energy expenditure over time. During weight loss energy expenditure is nowhere near this hard limit, but presumably the body can set different limits in different physiological states.
