Eating calories you burn by exercise question

Copy and Pasted answer I just wrote on another thread asking almost the exact same question....

Short answer: Try Searching this topic, as it has been discussed ad nausea here on the site.

Longer (but not nearly long enough) answer:
Your body requires a certain number of calories in order for you to simply exist. In order for you eyes to blink, your heart to keep beating, your hair to keep growing, your organs to keep functioning, you have to feed it a certain number of calories. This number is caleld your BMR. (Use the tool on this site to check your BMR...) For example, my BMR is about 1490 calories. So say Ilay in bed allllll day, motionless. I would require 1490 calories just to keep my body alive.
The second I get out of bed, walk across the room, open the door to the bathroom, brush my teeth, pee, weigh myself, turn on the hot water,and hop in the shower...I have burned calories. Minimal...but still enough to start cutting into the 1490 my body needs in order to fuel its most basic functions.
So if I eat my BMR of 1490 a day, I am only giving my body enough to do its basic functions.
MFP gave me a number of calories based on my desire to lose 2 lbs a week. At my height and current weight, losing 2 lbs per week is not reasonable, but the lowest MFP will set someone's calories is 1200 (For many good reasons). 1200 is sort of an arbtrary number at this point but no one should really eat LESS than 1200, and there are likely very few people who could eat 1200 calories for the res tof their lives and maintain weight or stay satisfied. (opinion...sorry) I lost 20+ lbs eating 1200 cals a day. But the second I started eating "normal" again, I gained all 20+ lbs back, PLUS MORE. It might "work" in the short term, but for many here, 1200 calories isnt the lifestyle change needed to STAY healthy and thin.

OK, back to the exercise thing. If I eat my 1500 (1490) cals today, my body will already be at a deficit for weight loss since I got out of bed, functioned, walked, lifted my toddler countless times, etc. So if I were to workout and burn 500 calories this afternoon, my body would be at an even greater deficit, and risk pushing my body to panic. Once your body panics and your metabolism worries that you are not feeding it enough, you will start to store fat at a faster rate. Your body and metabolism will try to hang onto any extra store of fat in preparation for an upcoming "famine".

Another way to look at it: If you eat 1200 calories and then exercise 500 calories away, you are only holding onto 700 calories for your body to draw from for energy, organ function, eye blinking, etc etc. Its just not enough for your body to exist on withut causing longterm troubles.

It took me a looooong time to "get" this. I still have to consciously remind myself to eat my calories in order to lose weight. It seems counter-intuitive...but it WORKS. When I eat my BMR and at LEAST half my exercise calories, I lose weight. When I only eat 1200 calories, I am miserable, hungry, and i might lsoe some weight initially...but i gain it alllll back with a few extra for fluffiness.

Hope that helped!

It is so funny that all our lives we are taught in order to lose weight we must eat less and frankly that is the exact opposite in most cases. The first answer that was posted is an awesome explanation of how it works. I worked out tirelessly starting in May 2009 but I didn't change my eating. I was eating what I thought was fine, english muffin and hot tea for breakfast, big salad at lunch with fat free dressing (great by WW standards so far) then at dinner I might have a piece of chicken and some veggies.... when I finally got fed up with gaining weight (July 2010) I asked my Dr and a trainer about this and was told exactly what that article says. I tracked my calories, carbs, fats, and proteins and found that I was only getting 900 calories a day mostly consisting of carbs. I had very little protein at all in my diet. So I started eating more and tracking more and continued to exercise and the lbs melted off. I have lost 23lbs since July, yes it takes awhile, it should. It is healthier to lose 1 - 1 1/2lbs/week then to lose 10lbs a week. You have a better chance of keeping it off if you lose it the right way and it is a lifestyle change. We have to change our thinking as eating more is the answer in a lot of cases, eating more of the right types of foods of course. I hope all of the replys are helpful and that you find the same success that we all have by taking control.