Maybe it gets hard to lose weight because, with more mass and volume, it takes less energy to stay warm.
The bigger you are, the lower your surface area to volume ratio is.
Your body has to maintain a temp of 37C (98.6F) so maybe a very large person’s body doesn’t have to work as hard to keep that temperature. Also fat insulates us.
Maybe someone that’s already lean burns more calories just to maintain body temperature.
For example, if two people were sitting still in a chilly 65F room, would the smaller person burn more calories?
FYI: shivering can burn 100 calories in 15 minutes.
Yes, different people can burn calories faster than others. And the same person can burn calories at different rates at different times. For a while, it was believed that exercise tends to raise your resting metabolic rate, but recent studies don’t support that claim. But it has been shown that drastically cutting back on food intake can cause your body to go into starvation mode where your resting metabolic rate drops. I don’t know what it takes to make it go up. Recent research is looking for links to microbes in your gut.
Also, not true that everyone maintains a body temperature of 98.6. Except in the middle of a heat wave, my body temperature tends to be maybe 97.2 or so and so is my wife’s.
It depends mostly on the amount of exercise a person is getting. Those skinny bicycle racers can burn more calories daily during something like the Tour de France than an NFL lineman weighing twice as much.
Cite? It’s true moderate exercise doesn’t, but it’s been verified that vigorous exercise will.
Yes, but both are burning between 5,000 and 10,000 calories/day. If exercise didn’t raise their metabolic rate, they’d both be putting on some serious pounds. (Note: despite the fact that linemen weigh a lot, they actually don’t put on significant poundage during the season.) The extra burn during their competitions/training isn’t enough to burn off those calories, which are double or more what non-athletes consume.
Correct - which means the energy expended by the larger person to stay warm is a lower percentage of total metabolic energy expenditure than for the smaller person. But in terms of absolute energy - total calories burned - it will be higher, due to a larger total surface area. This would be mitigated to the extent that larger people have a lower surface temperature, but I doubt that’s a big difference.
And of course pretty much any movement costs more energy for the larger person, due to the greater mass being moved.
Here is a paper published in 2007 which did a meta-analysis of several studies, some of which seemed to conclude that exercise increases RMR (resting metabolic rate) and others which fail to find such a link. Speakman and Selman noted that many past studies tested the subjects’ RMR within 24 hours of recent exercise, which could skew the results. A true measure of RMR requires that the subject not exercise for 36-48 hours before the test. Apparently, exercise burns more calories while you’re doing it and also increases your RMR by about 10% for the next day or two because of Excess Post-exercise Oxygen Consumption (EPOC), but your RMR will fall back down again after that and sometimes will actually fall below what it was before.
Apparently people with a higher muscle mass tend to have a higher RMR. But increasing your muscle mass by exercising more may have the opposite effect from what you desired. Here’s a quote from the study linked above (bolding mine):
OK, I think the problem is definitional. Or maybe it’s just my definition versus the academic one.
EPOC is raising one’s metabolic rate and you get that from exercising vigorously. And exercising every day, or close to it, will result in one being effectively in an elevated metabolic rate, what that quote calls “long-term EPOC”. So they only considered it the base metabolic rate if they have the people stop exercising for several days (probably have to wait about a week or so) before measuring it.
So it looks to me like they’re changing the definition. You can’t stop exercising; there is no finish line. You keep exercising and your metabolic rate will stay elevated. That should be the normal state of being for pretty much everyone. Instead they think being a couch potato is the normal state.
Ummm…hate to break it to you on which of those is the normal state, but I’d say this is one of those times they got it right.
Your “normal state of being” of vigorous physical activity 4-5 times a week without major breaks is probably true for between 0% and 10% of the population depending on age bracket. I’d say betting on the normality of couch-potatohood is one of the safest bets you can make at this point.
It was the normal state throughout the vast majority of human existence. In fact for 100% of all humans before 6 to 8,000 years ago. It’s only in the last 100 years that it has stopped being that for even a majority of people. We need to get back to that. Forget the “Neolithic diet”; try the Neolithic exercise regimen.
Most of your calories don’t go towards keeping warm, given central heating and clothing. You probably wouldn’t even shiver vigorously in a somewhat cool room while dressed, and wouldn’t burn close to 400 calories per hour.
But people follow bell curves and some small people may burn more calories than larger ones. They may be more muscular, use energy nor efficiently, be fidgety, have more active metabolism, be hyperthyroid, etc.
What about a small person drinking large amounts of ice cold water? The very first time i competed in a bodybuilding competition and had to drink gallons of water a day, i drank it extremely cold and was convinced that it helped me lose enough fat to get me down to the lowest bodyfat % that ive ever achieved (3%). I couldn’t tolerate the freezing cold water any time after that lol. The 20’s are an enviable decade.
Regardless of whether you consider RMR two days after exercising to be the default condition, the point remains that calories burned correlates very strongly with non-fat body mass. If you have a person who weighs 160 lb and has only 10% body fat, then their non-fat body mass is 144 lb. Find another person who weighs 200 lb and has 30% body fat, their non-fat body mass is 140 lb. If they have similar exercise routines (or lack thereof), the 200 lb person probably has a lower RMR than the 160 lb person does. Put the 200 lb person on a “boot camp” program and their RMR will drop even further.
