A little while back, I made a stupid statement. I said, "muscle weighs more than fat". It's what I'd always heard and I accepted it as fact - just like why I put ketchup in the fridge. I grew up putting it in the fridge and so that's where it goes.
At any rate, a friend picked up on that and nicely gave me a (soft) slap upside the head. 5 pounds of weight will always equal 5 pounds of weight, yet it's MASS may be different. It was, for me a "duh!!" moment.
I am now regularly seeing on Facebook now people saying how muscle weighs more than fat and I laugh. Sometimes I chime in and explain the difference but it seems to be such a commonalty and universally accepted.
How many other things do we do because we've not questioned the thought, be it light silly things like putting ketchup in the fridge to heavier topics such as not needing to get your affairs in order because "I'm too young to die, I still have time"? Seems to me we need to take a look at our beliefs and not just blindly accept them.
By the way, ketchup does indeed have a shorter shelf life if left out.