Unfortunately, human body doesn't work like a mechanical engine which input fuel and output work.

If you increase your calories consumption by exercise, our body reduce the calories consumption of non-vital activities to keep the calorie consumption budget.

Unless you're running ultra marathon every day, you can't increase calorie consumption that much.

> What evidence is there for this? All the things that calculate approximate calories burned for various exercises tell me that it's not minimal.

Minimal meaning that the amount of exercise you need to do to burn substantial amounts of calories is quite high. Your example of 500cal would be something like an hour of moderate intensity jogging, which would be a lot of exercise for someone to do every single day.

Meanwhile, eating 500cal takes like... 5 minutes? Less?

> Obviously diet is the biggest factor, but if you just eat less and sit around all day, you body will adapt to the lower calorie intake and slow your metabolism down too and you will have to eat so little that you will never feel full or satisfied (so you will probably not be able to keep that up for long) and you will feel like crap and have no energy if you don't combine with exercise, at least in my experience.

Metabolic adaption is largely overblown. You definitely will burn less calories as you lose weight, but that would happen exercise or not. The only difference there is that exercise tends to build muscle, which would burn more calories and offset some of that loss. The fact of the matter is, if you end up losing substantial amounts of weight, you will need to eat fewer calories to maintain that same lower weight forever.

In my experience, if you're losing weight then you are often going to feel not full. It's just a natural human reaction to caloric deficit. There's tricks to making it not be as impactful (e.g., eat more whole foods, less junk, etc) or medication to make it less of a problem (i.e., GLPs), but expecting to be able to lose weight and always feel full just by adding exercise is wishful thinking.

When I trained for a half marathon, I didn't lose any weight. I just became very hungry.

(And, unfortunately, when I injured myself, I kept being hungry - and gained mass)

Calories in Calories out, but that is only accurately calculable if you have an accurate idea of how many calories you are sending out, and if you are obese or formerly obese, the online calculators are likely not accurate for you at all.

One thing that is overlooked is that losing weight can permanently or at least semi-permanently decrease BMR, your Basal Metabolic Rate.

Your BMR is the calories you burn just to be alive, and is the foundation of almost every calorie counting system in the world.

At my worst, as a 33 year old 250lb 6'1" man, my BMR was at 1,836 Calories/day when it should have been at 2,133 Calories/day as diagnosed by a dexa scan and calorimetry test.

A 300 calorie a day decrease in my BMR from losing 100 lbs meant that I have to either find a way to increase my total metabolic burn or I have to permanently cut almost an entire meal from my diet for the rest of my life.

This was helpful and harmful in a way. It explained why when I was eating 500 calories a day under what my calculator said I should be eating I was barely losing a pound or two a month instead of a pound a week like I should have.

I was also tired and hungry all of the time, no energy, irritable and unhappy because so much weight loss had changed the way I function.

But when I quit the diet, I put on weight like crazy. I put on like 20 lbs in a couple of weeks and I didn't eat that much more than usual.

I've been checked for thyroid issues and diabetes, fortunately clear there, just a literally slowed metabolism as a consequence of losing 100 lbs.

There are things I can do to speed it back up, like going to the gym and putting on as much muscle as possible, but that also takes time and effort and work and it requires overeating and gaining weight at the same time.

Basically, once you're on a diet, you're always on a diet for the rest of your life, and the more weight you lose, the harder it becomes to lose weight if your metabolism is altered by your diet in the process.

If you're having trouble losing weight, get a Dexa scan and calorimetry test. That will identify where the fat is in your body and how many calories your body burns just sitting there doing nothing.

Once you have that data you can more accurately plan your diet to stay close to the 500 calorie/day limit to healthily lose weight. Just make sure you get re-scanned every 20 lbs or 6 months, it's not that expensive and gives you good information.

I spent a year powerlifting and lost absolutely no weight, then spent 2 years powerlifting while restricting myself to 1800 cals/day and lost weight. If we're doing personal anecdotes.

If we're doing hard data, I think you're overestimating the impact of taking 500 calories a day off of the average American's diet, which comes in at around 3800 calories/day (https://www.ers.usda.gov/data-products/chart-gallery/chart-d...). Assuming 3300 net calories per day after exercise, one would have to be in the neighborhood of 400 pounds for that to be below maintenance level assuming 40 y/o moderately active based on the mayo clinic calorie counter (https://www.mayoclinic.org/healthy-lifestyle/weight-loss/in-...). Hell, I ride a bike 6 miles and lift weights every day, have done for two years, and my maintenance calories are still only in the 2200-2300 range, which means if my diet was average I'd be exercising every day and still putting on pounds rather quickly. Tldr - I think your results are an outlier because you've underestimated how much better your existing diet is than the average.