After finding out that a Quarter Pounder from McDonalds lost 35% of its weight during cooking, I had to find out if that was a typical change, or if McDonalds was using super-fatty mystery meat in their burgers.

The highest marked fat content I found for ground beef was this 80% lean, 20% fat ground beef.

In the market, this package of hamburger meat cost $4.11, making each 4 ounce burger worth 82¢ (price before cooking).

I had a theory that the 20% fat would melt away during cooking, leaving 80% of the weight behind.

I split the meat into four ounce balls and shaped them into burgers.

It was during this shaping process that I came to understand what a huge amount of moisture was in the beef. They were wet!

Of course. It isn't just fat leaving the burgers, it is water... a lot of water.

I cooked them in a hot pan, turning them occasionally.

I heated them up until the internal temperature reached 160°F. At the end, the pan was greased with a layer of melted fat, but it wasn't more than a tablespoonful. Most of the weight had escaped as steam, floating into the air. The burgers were cooked. I pulled them out an checked them one at a time on the scale.

All of the burgers had started at 4 ounces, and sure enough, they were each 2.6 ounces when I was finished.

McDonalds isn't using inferior beef, and they aren't using superior beef either. Their quarter pounder cooked down to the exact same weight.