Yeah, you're ridiculous. It seems like you're trying to lose weight eating that much a day. The 2000 Calorie diet was arrived upon because it is the average number of calories that a person needs to consume to keep them energized and functioning during normal daily activity. Athletes however need more. I assume you've heard that swimmers consume upwards of 10-12k Calories a day during hard training periods? Though many of us don't swim 15k yards a day, running 12 miles or biking 50 burns calories, so if you're engaging in any supplemental physical activity you already need to eat more than the 2000Cal average. Fainting should have been the first thing that tipped you off that there's some kind of problem, I can't imagine just shrugging that kind of thing off. Your body is a machine, if you don't give it enough fuel it won't run. Though your workouts have not suffered yet, I expect that they soon will. Good luck.

I understand where you're coming from... I eat pretty/really nutritiously but don't really concern myself with caloric intake. When you step back and actually think about how much you're taking in especially eating fresh fruit, lean meats, whole grains, etc it can turn out to be a lot less than it seems. I had a very tired few weeks some years ago while swimming in college, and not from the yardage.

Base Metabolic Rate is pretty close to accurate. I'd say within a 150 or so calories. Definitely sounds like what you are doing is not eating enough. You don't necessarily need dense calories but you need to eat what you are burning or you will lose. And muscle at that if you're not careful.

I always know when I haven't eaten enough for the day when I get a bit light headed upon standing....EAT! Just don't overdo it.

I personally think the BMR calculators are full of shit.

Per calculator my BMR is 1408 and at 2-2.5 hours of training a day (my norm) it puts me at 2400-2600 kcal. I got my BMR from my RMR after a 12 hr fast at a sports nutritional clinic - my BMR is 1820, that would be sitting on my tail, and this is before I was training for am IM, or even an HIM. That's a 400 kcal deficit IF I went off of the online calculators.

I think I'd die if I only had 1400 kcal, that or I'd kill someone.

BMR (RMR) is a term. It is based, when predicted, on height and weight and gender and age.

It's "accuracy" depends on how you measure it. In this case you're not measuring it, you're predicting it. The "gold standard" is something called calorimetry. You can have this done at a hospital that does clinical research or you can have it done at some gyms using a handheld device like the Body Gem (I don't recommend the latter).

You can also use prediction equations like the one you mention (there are a few and they are based on large #s of patients and make certain assumptions). Their validity is limited, as CJ points out, by body composition.

I think there are a couple of issues here. One, it seems to me that you may not be eating enough, hence the weight loss. But you can be losing weight for other reasons as well and those should be investigated. 10# in 3wks is a fast rate of wt loss...have you changed your diet or training volume during this time?

The other, possibly unrelated, but more concerning issue is the fainting. Lots of things can cause fainting and this should be investigated by a medical doctor.

Why don't you go for a check-up then we can continue the discussion of BMR...

Walter