Okay. Please bear with me because a lot of people usually come in and ask these questions. I'm new to the whole weight loss thing. But I'm mostly concerned with body fat percentage, not actual weight.

Anyways. I was wondering the totals of calories and how it all boils down. I know that I ate a total of 1380 calories today. I did 2 hours of high impact aerobics totaling to 354 calories burned. Does that mean because I exercised today's total calories is 1026? Is that healthy?

If someone could explain to me exactly how this all works that would be wonderful. According to PUSH I should be having an intake of 1945 calories. (taking 2245 and subtracting 300 to lose weight) So I know todays was a little low. My resting Metabolic rate is 1449 calories. Does that mean I need to burn 496 calories a day? Thanks in advance to help me sort this out. =)

Well, you asked a lot of questions. I'll try to answer some of them.

First, if you ate 1380 calories, that's what you ate. The exercise doesn't subtract from what you ate.

Second, there are a million calculators, and they are all estimates. I think it's important to know that.

Your intake is made up of what you eat. Think of your output (calories burned) as made up of 3 parts:
- RMR -- resting metabolic rate. This is the calories you'd burn from basic functions -- if you slept all day.
- general activity. Everything you do burns calories. From brushing teeth to driving, to doing the dishes.
- exercise.

Theoretically, if you want to lose weight, your intake should be lower than your output. If you want to lose 1/2 pound a week, your intake needs to average 250 calories below the calories you burn (output) per day. The difference between the two is your calorie deficit -- provided intake is lower than output.

Now of course, it's hard to calculate the output exactly, as everything is an estimate. And you do not need to really know your deficit. Many people do some trial and error to figure it out. They write down everything, for a few weeks, and see how much they lose. You need to do it for a few weeks because lots of factors can affect the scale, especially water retention.


Does that help?

2245 is what your body burns in a normal state just existing (BMR of 1449), doing your normal daily activities, plus normal exercise. If that aerobic activity was IN ADDITION TO your normal exercise, you get to add that to that number = you burned 2599 calories that day. Since you only ate 1380 calories, that means you ran a calorie deficit of 1219 calories. You need to accumulate a deficit of 3500 calories to lose 1 pound. So you lost approximately 1/3 of a pound that day and will continue to if you keep up that activity/calorie level (you will continue to lose a that rate for a bit until you are lighter and have lower calorie needs, then you need to recalculate).

If you are comfortable at 1380, it's not too low a level as long as you make sure you're getting enough protein, fiber, and vitamins in your diet (ie, it's not 1380 calories of junk food!). The lower your calorie level, the quicker you will drop pounds and fat ... but the general consensus is that eating less than 1200 calories a day is unhealthy (you can't get enough protein/vitamins/other nutrients below that level).

1026 net calories is on the low-side. I think most doctors say try to eat atleast 1200. It's all a personal thing though and everyone is different.

If it was me I would add just a wee bit. It will help to prevent losing as much lean body mass if your body has enough calories to work with. That being said your not THAT much under recommended level so if your aiming for 3lbs a week I think you'll be fine at your current level if you're feeling good about it.

With everything I read, you don't want to cut your calorie intake very low because that slows your metabolism down.

the simplest fact I keep in mind is that 1200 cal is the MINIMUM your body needs to function normally. When my friend decided to stay at 1000 calories a day (for a few months), she lost weight but also lost a lot of hair, and i'm sure she was fatigued. however, she has gained some of it back already.
hope that helped! I just always try to remember 1200 as the minimum.

leda