Obesity due to medical problems. Rare? Common?

Definitely. I’ve posted before how amazed I was (and continue to be) at the number of calories I consumed through beverages through highschool and early college. I drink like a fish, and I don’t drink water all that much. It would not be uncommon for me to have a 20 oz. bottle of soda or “fruit juice” (not really juice, but one of those fruit-flavored drinks) or two at lunch, another when I got home from school, and still another one or two over the course of the evening. In college, I would frequently have one or two of those fancy Starbucks carmel latte fancy-named things (we had a cafe that served Starbucks in the dorm, and we could use meal points there). It is probably not an exaggeration to say that some days I might have gotten half of my recommended calories from beverages, if not more.

Aside from drinks, people tend to vastly underestimate portion size as well. If you look at the calorie amount on the box and it says “100,” and the serving size is tiny… For example, I’ve got a package of glazed walnuts here. It says “140 calories,” which isn’t great, but it isn’t bad. The serving size is 1 OZ. (about 1/4 cup). That’s tiny.

This argument assumes that all people metabolize equally efficiently. Why does my truck get worse mileage than my car, which weighs the same?

Of course people don’t metabolize equally efficiently – but that argument only holds within a certain range.

Taken as a given that people have a relatively stable body temperature (though of course that is different for different people), it takes a minimum amount of calories to maintain that temperature, no matter how efficiently or inefficiently your body processes food. You MUST be using some energy (whether from stored fat or from food intake) to maintain that temperature, else your temperature would be declining. Likewise, it takes a minimum amount to maintain brain function, and to perform physical movement.

And that’s why I just can’t wrap my head around the “I only eat 800, 900 or -1000 calories per day” claims some people make. Metabolic diseases or not, you start getting much below 10 calories per lb of bodyweight per day, and you’re not going to be able to maintain body temperatures (asuming no substantial fat reserves) . PCOS and related diseases may screw up the way your body processes food, but it’s not going to let you live on a reptile level energy intake. It cannot be done.

And that’s why I just can’t wrap my head around the “I only eat 800, 900 or -1000 calories per day” claims some people make. Metabolic diseases or not, you start getting much below 10 calories per lb of bodyweight per day, and you’re not going to be able to maintain body temperatures (asuming no substantial fat reserves) . PCOS and related diseases may screw up the way your body processes food, but it’s not going to let you live on a reptile level energy intake. It takes X amount of energy to keep the big bag of water that is the human body heated up and running. It cannot be done unless your body temperature is being substantially lowered somehow.

Or, and this shouldn’t be discounted, the individual has turned themselves into a perpetual motion machine.

Well, I dunno. I actually use Fitday, and I measure food (which is super fun!) so I know almost exactly how many calories per day I get - 900 at the most - 700 is usual.

Now, my normal body temperature is quite a bit below “normal” - around 96 degrees. If that’s making all the difference, great.

But I know how much I eat, I know how much I exericise, and I know how big I am. Perhaps I defy physics - it wouldn’t be the first time I’d heard that… :wink:

FWIW, the Dr. just increased my medication, despite getting “normal” test results, and I’m actually starting to feel like myself. That’s one thing with thyroid disorders - the range of “normal” is huge - you can get test results that fall within the appropriate guidelines, and still not be functioning normally, which is obviously very frustrating.

http://www.thearc.org/faqs/pwsynd.html

Prader-Willi Syndrome effects only 1 in 14000 so is a rare medical problem associated with obesity. PCOS is much more common.