Okay, so I keep hearing that for every 30 lbs a guy loses (actually I've heard other versions where it's 10 lbs, which just strengthens my opinion on the subject) his penis gets an inch longer. To me, this freaking REEKS of BS, but I have friends who believe it or aren't sure. I've looked everywhere and can't find solid information one way or the other. Experts seem to agree that the ONLY thing that can increase penis size is time, which would run contrary to this story. Can you confirm or deny this?
Like any myth or urban legend, there's just enough truth involved to make something sound reasonable or make people question it.
Just like any other part of the body, when one's weight changes, it makes the body look different than it did before the weight loss or gain. So it would not be unreasonable to say that after a significant weight loss, a man's penis might appear to be larger than it did previously. This could be caused by a combination of things. First, if one's body is big in general, smaller parts may tend to look even smaller in relation to the rest of us. The same thing could be true for a person's hands or feet. Also, if the man in question is significantly overweight or has a great deal of belly fat (or what's sometimes referred to as an "apron" of fat and skin on the belly that hangs over the waist), it could obscure the penis to some extent. If that weight is lost, the penis will appear to come out further from the body or appear larger. This does NOT mean that any actual change in size has occurred, it just means that the part of the penis that is easily visible outside the body is more apparent. So no matter how much weight one gains or loses, it is not actually going to change the size of one's penis.
In essence, penis size is determined by the same things that determine the size and shape of any other of a person's body parts. Our genes determine a great deal of the way we look in general and this is true for our genitals as well. Also, where we are in terms of physical development is going to play a role. As puberty progresses, we generally see the genitals change as well. Otherwise, the only way to actually change the size of one's penis in any permanent manner is surgery. (You'll notice that I didn't say medication. The supposed pills, creams, and what have you that are sold are basically a bunch of bullocks. There is NO unbiased, scientific study to indicate that these products work. In fact, one of the main companies that manufactures and markets a well-known supposed "male enhancement" products is in litigation over the claims they made which have been shown to be scientifically false.) The surgical options for changing the size of one's penis are not particularly pleasant or effective either. Fat can be injected under the skin of the penis, but generally this ends up simply resulting in a lumpy penis since the fat tends to accumulate in spots. Some surgeons will also do things like cutting a ligament that holds the penis up so that more of it appears outside the body. This isn't so great either since the actual change is very small and it results in a penis that significantly droops (among other potential problems).
So in general, aside from some rather unfortunate surgical procedures, there's nothing that's going to change the size of the penis other than genes and normal physical development.
You may want to check out our article Anatomy: Man's Best Friend for more information about male sexual anatomy.