1000 calorie deficit?

I know they say 500 cal deficit. Typically I am about 500 deficit. I have a desk job and burn about 1700-2000 a day just walking through the office. I eat from 1200-1500 cals per day. But on days (about three to four) out of the week that I go to the gym I burn 400-1000 calories in cardio but I don't up my calories for the day. So, last night I burned about 3000 calories including the workout and I ate 1300 calories. I'm thinking this is bad. But why? Wouldn't this just help me lost weight faster?

My understanding is BMR X activity level equals your burn calories per day How are you burning 3000 calories? ? typo, 300 perhaps? (choosing the right activity level is to include what exercise you do right?) Newbie here, just trying to understand.

oh, it's no typo. 3,000 cals daily on workout days. Meaning, at my job, running around the office I burn typically 2000 daily. Then I hit the gym for an hour or so of intense cardio and burn approx. 1000. So, yea, some days 3000 throughout the entire day.. But, cals are still about 1500 intake. So actually I was 1500 cals deficit. But yea. I'm a newbie kind of too so it's okay! I joined in December but never actually did anything on here until the past few weeks. I'm learning too.

I assume she meant 3000 calories TOTAL burned for the day, not just in the workout. :-)

If you have more than 1000 calorie deficit, you risk sending your body into starvation mode. Your body will know it's not getting enough calories to support the exertion it needs to do, and will start holding onto fat. Our bodies are hard-wired to keep us alive even in extreme conditions. You have to trick it into letting go of fat by having a smaller deficit every day. 500-800 is a safe, reasonable deficit.

So the 1500 calories deficit yesterday was a HUGE no no huh. Noted, thankyou!

"If you have more than 1000 calorie deficit, you risk sending your body into starvation mode. Your body will know it's not getting enough calories to support the exertion it needs to do, and will start holding onto fat."

 

I think it matters more that you eat at least your BMR more than it matters the deficit with regards to the dreaded "starvation mode."  On days I go to the gym, I frequently will burn between 4,000 and 4,500 cal.  My BMR is 2230.  If I eat 2630 calories (as I did today) and burn 4,290 (as is projected today), my body will most assuredly not think there is famine and start storing.  That is a 1,660 calorie deficit, but I'm getting plenty of calories.  

Your 'safe' deficit is the amount of calories you can have as a deficit before your body starts to burn lean body mass - which is bad. You want to burn only fat.

Determine your safe deficit to burn only fat by multiplying your body weight by your body fat percentage (which gives your you fat weight), then multiply by 31 calories per fat pound. This is your maximum safe deficit.

The same source tells me that a safe, healthy rate of loss is a deficit of 20% of your maintenance calories. Source:

http://www.mindandmuscle.net/mindandmuscle/pr int/printview.php?artID=35

This source doesn't talk specifically about eating back exercise calories, but I wouldn't go past the 'safe' deficit at any rate, as the reason for doing so (above) doesn't have anything to do with the starvation response. I disagree with kalebr above that you only need to cover maintenance calories, because your body doesn't know how it's burning energy, just that it is. However, I do agree that when I have a high burn day, I don't need to eat it all back, but will if my body asks for it. 

So, on high burn days, I would recommend the 'safe' deficit, otherwise the 20% (which often translates to 500 cals for the 'average' among us. 

the other thing to remember is that the 500-1000 calorie deficit is a PER DAY thing, and that in reality your body doesn't count by day, it kinda averages things.  So if you were at a 1500 deficit every day, your body would begin to rebel, losing muscle mass, reducing fat burn, etc.  But once in a while isn't going to trigger starvation mode.  if you have 500 deficit 4 times a week, 1000 2 times and a 1500 one day you are fine.  2000+2000+1500 = 5500/7 =~ 785 which is fine. 

 

hkd bear - I just did your calculator for myself and I got 3317.  Does that mean that since I have so much fat to get rid of it is safe to have a higher than 1000 calorie deficit?  For example I put in my workout this morning and now my burn meter shows and estimate for today of 3560.  2500 calories seems like alot to me now that I have started this.   I usually eat around 1600 a day.