> I've known very active cyclists that couldn't lose weight despite riding hundred mile rides weekly.

Isn’t this against the laws of physics? If you’re burning a ton of energy and not eating excessively, where are their bodies getting mass from to maintain weight?

100 miles weekly isn't THAT much in terms of kcal. 10 miles is about 600 kcal. 100 miles is 6000 kcal, let's say 7000 to round that to 1000 kcal a day.

Eating 1000 kcal more a day is pretty easy to do without noticing. Especially when you eat a lot on the day that you biked (cause "you earned it").

For example 2 liter bottle of coke is 800 kcal and 1 protein bar is about 250 kcal and you're already over the budget (assuming you also eat your "regular" food).

I think most people (especially people who think they're eating healthy) would notice a 2L bottle of coke.

I agree with your point. In fact I think it's even stronger as I don't think 10 miles on a bike is anywhere close to 600kcal unless we are talking very serious hills on a MTB. 10 miles on a flattish road is usually half an hour of moderate effort.

Paradoxically, pushing a larger body through wind resistance should burn even more calories! The people I knew weren't explicitly trying to lose weight, they were cycling for their cardiovascular health and on that front their doctors were happy. But, yeah, distance cyclists tend to eat their fill.

> Isn’t this against the laws of physics?

No because they were also eating a lot, the lower bound on this established by physics.

I've known a lot of roadies who sort-of-correctly believed they could eat as much as they could physically manage, as they were expending enough (3+ hour intense riding daily) that it was a chore to keep up. At least when they were 20-something and racing. Many struggle a bit when the a) get a bit older/metabolically slower and b) life gets in the way and they ride a lot less. All of a sudden a guy who was rail thin gains 30lb that "sticks".

> couldn't lose weight ... they were also eating a lot

So really it's that they weren't losing weight because they were eating too much... exactly like most people in modern western society. And really the moderate amount of cycling was irrelevant.

The operative word was "couldn't". If they didn't eat as much, they could lose weight

I would guess that they are very metabolically efficient bicyclists and that they underestimate how much food they eat.

I think this is pretty common for people who exercise intensely. If you don’t increase your eating, you’re going to 1) feel hungry all the time and 2) negatively impact your performance. I trained for a marathon two years ago after only doing half marathons. I basically couldn’t lose weight unless I trained less.

As someone who exercises a lot, the body ends up being extremely hungry all the time similar as to when I hit puberty as a child. `

Doing tons of endurance cardio gives you massive carb cravings and catabolizes muscle mass, slowing your metabolism. Especially when none of it is max effort. To keep your body fat percentage low and metabolism up you really need to combine endurance cardio with high intensity cardio and strength training. This is why things like Crossfit and HIIT are so popular.

Sorry I just don't agree with this. I run 50 miles a week and mix in some cycling too, and I actively have to make an effort to eat enough to maintain weight. Endurance cardio doesn't trigger hunger or cravings for me unless it's a long (90 mins plus) effort.