It's agreed that 3500 calories is roughly equal to one pound (i.e. if you eat 3500 calories more than what your body requires, you will gain 1 pound). But 1 gram of pure fat (lard) has 9 calories. 453 grams per pound means that 1 pound of pure fat has 4077 calories. Thus, if you eat 1 pound of lard, you will gain MORE than one pound of weight (about 1.16).

 

This defies what I know about conservation of mass. What am I doing wrong?

It's agreed that 3500 calories is roughly equal to one pound...

yeah, but one pound of what.

One pound of sacarose has less calories than one pound of proteins. And one pound of proteins has less calories than one pound of pure fat.

 

You have to define one pound of what!

2 possibilities leap to mind: 9 calories per gram is an appproximation, and/or the molecules bind with oxygen that you breathe in, adding mass.

 

edit: and molecules can bind to water, too. No calories, but there's more mass.

For one thing, fat cells are not pure fat. They have some structure to them, which adds weight. You may also need extra water. For example, chickens can lay more weight in eggs than they eat in dry food, because of the extra water. Just remember, calories are not mass, they are energy.

Inevitably, the answer is no. Fat is burned, wasted, and of course, stored. Besides the math of it, it is impossible to gain more weight than the food that you eat, but you can drink enough water to make up for the difference.

 

By the way, a pound of sugar or proteins only equals 1,812 calories.