Tip For Females to Adjust Cardio Calories Burned

I have a tip I use when figuring out how many cardio calories I have burned.  This stems from something I read in David Greenwalt's book "The Leanness Lifestyle", which I consider my fitness bible.  In the book he states that it's reasonable to assume that a man working very hard burns 10 calories a minute and a woman 8.  Since he goes off of scientific studies and not hunches, I trust David's book and the things he says in it.

I've always felt like cardio machines are a little generous when it comes to how many calories they say I burn.  I wanted to adjust it to be on the safe side of realistic for my logging purposes.  So, working off of the 10/8 rule above, it's fair to guess that we women burn about 80% of the number of calories men doing performing the same activity at the same intensity.  (8 is 80% of 10.)  I assume the machine thinks I am a man, since while I have had a machine ask my weight and age, I've yet to see one that asks my gender.  Given that, I take the total amount of calories it says I've burned and reduce it by 20% to give me 80%.  (This is easier mental math for me than multiplying it by 80%)

So if I worked out on the elliptical machine for 45 minutes and it says I burned 450 calories, I assume I burned roughly 360 calories. (20% of 450 is 90: 450 minus 90 is 360.)

To break it down even further for my usually-exhausted mind at the end of a tough cardio workout, I just double what 10% is to come up with the 20% number, since 10% is easier to tell at a glance.  So in the case of the elliptical workout above, 45 is 10% of 450.  45 times two is 90.  So 90 is 20%, or what I need to subtract from the total the machine is giving me.

Everyone following?

My personal method for logging my food and exercise is in my Weight Watchers tracker, which we all know uses a point system instead of calories.   I assume every 50 calories is 1 Weight Watchers point.  So I round the number I came up with (360) down (not EVER up- I am trying to err on the side of caution) to the nearest 50.  For the aforementioned elliptical workout, this would give me 350.  Then I just divide by 50 to come up with the number of Points to check off in my exercise tracker- in this case 7. (350 divided by 50 is 7.)

This is all very rough and by no means terribly accurate, but I've found it's a good way to guess.

If you are a man, forget it.  As long as you entered your age and weight into the machine, just go with the number it gives you.  If you are a man using the Weight Watchers system, round that number down to the nearest 50, divide by 50, and there 'ya got your exercise points.