Weight Loss

For years I've been weighing myself first thing in the morning, before I start being more active and the muscles warm up with activity. Somewhere along the line I picked up the idea that muscles that are at rest/cold, whatever you want to call it, weigh less than muscles that have been worked. I can't remember where I heard this and I can't find anything about it on the Internet. Is this a myth? Or is there any truth to it?

Original Post by mageeg:

is there any truth to it?

No.

Actually, the muscles themself may weigh more, as active muscle receives a much larger percent of your blood supply than resting muscle. But this wouldn't make you weigh more when your muscles are warmed up, as the blood is just diverted from the rest of your blood supply that is already there. Any weight gain throughout the day is from food or water.

No. if you are talking about weight before vs. after workout, the extra weight from measuring is probably because of the water you drink during workout.

a physical thing will have the same mass no matter at what temperature, it's density might change if it expands etc. but it should be the same.