I just wanted to say that I generally agree with the above (was unsure whether to reply to the parent post or this one). My only real quibble is that I think the protein requirement is too high (even of lean mass). Possibly I'm a special case, but 0.6g per lb of lean mass has been enough for me to gain muscle.

The "ultra efficiency mode" is definitely one of the more unfortunate things to come out of the low carb camp, IMHO. generally speaking, unless you have a disease or physical disorder (like hyper thyroid) you are going to be burning/eliminating about 1400 - 2500 calories a day. It can be quite a bit higher for some diseases or disorders where you can't process food.

Running is a great exercise for counting calories because it expends a pretty predictable 80-110 calories per mile (depending on pace). Other exercises can be extremely variable (to the point where I have seen people overestimate the calories by factors of 3-5). Do not trust exercise machines for caloric output. Every single one I've seen is off by at least 50% (they flatter you so that you demand their machine).

But generally speaking, if you do aerobic exercise continually for 1 hour, you will burn 5-600 calories. If you eat 1600 calories, then you will have a balance of about 1000 calories, which will certainly be in deficit for the average person (if you are really small, then it might not be, but I suspect it will be even then).

So why do people hit plateaus?

- They vastly overestimate the calories burned from exercise.

- They vastly underestimate the calories eaten.

Mostly it is the latter. It is not hard at all to put 100 calories of butter on a slice of bread. It is dramatically easy to put 200 calories of salad dressing on a salad. It is easy to say, "I only had a muffin and a coffee for breakfast" without realizing that said muffin (with butter) and coffee (with cream and sugar) could easily be in the 500 calorie range. My friend used to go to subway for lunch and have a 6" salami sandwich, one of those small bags of chips, and a sweetened iced tea for lunch. He had no idea he was pushing 1000 calories for lunch (the muffin and coffee for breakfast, 6 inch subway sub for lunch and... sorry... maybe you can have half an apple for dinner).

So, it is quite easy to loose weight when you are 220 lbs and burning 2500 calories a day. But then when you get down to 170 lbs and are burning 1900 calories a day, suddenly that miscalculation for how much exercise you are doing, or the 300 extra calories you are eating, but didn't realize makes a massive difference. Similarly, if you have health issues (especially digestion) that cause you to eliminate food rather than digest it when you are heavier, it can make a dramatic difference later if you get healthier and start actually processing this food.

The overestimation of exercise is a bad one because it is often fuelled by industry lies. Go to a gym and someone will tell you that you are burning 1000 calories an hour lifting weights, or that adding a kg of muscle will increase your metabolism by 100 calories a day or some other such nonsense. My brother (who is otherwise a very intelligent person) once thought that he could burn 1600 calories an hour on a bicycle (possibly if he is in the Tour de France, but pushing 150 watts is more than most beginners can handle for an hour and results in 540 calories an hour). Stuff like that makes me fairly angry...