In my last post about the 350 Calorie Solution, I mention that a pound of body fat is equivalent to 3500 calories. However, if you know anything about fat calories, you might have been surprised by this statement. Why? A gram of pure fat contains 9 calories and there are 454 grams in a pound. As a result, the simple mathematics would suggest 9 x 454 = 4086 calories!
So, what is going on?
The good news is there is no discrepancy.
Human fat cells can store over 90% of their volume of fat; however, they also contain water, proteins, and carbohydrates. Remember: water has no calories so its presence reduces the total calories within the cell. Since adipose tissue (or body fat) is not pure fat, the calorie count for a pound of it is ~3500 calories. This means that adipose tissue is about 7.7 calories per gram, not 9 calories per gram.
However, a pound of pure dietary fat would indeed be 4086 calories.
I hope this explanation makes sense why it is appropriate to say it takes 3500 calories to burn a pound of adipose tissue, but when discussion the nutritional content of food that a pound of dietary fat would be 4086 calories.