Some men have a penis that curves to the side, upward or downward when erect. This is common, and a bent penis in most men isn't a problem. Generally, a bent penis is only a cause for concern if your erections are painful or if the curvature of your penis interferes with sex.
When you become sexually aroused, blood flows into sponge-like spaces inside your penis, expanding and stiffening it. A bent penis generally occurs when these spaces don't expand evenly. Most often, this is due to normal differences in penis anatomy, but sometimes scar tissue or another problem causes a bent penis and painful erections.
The typical erect penis is usually 5 to 6 inches long with a circumference of 4 to 5 inches. There's more variation in the size of flaccid penises.
Some guys are genuinely smaller than that. In rare cases, genetics and hormone problems cause a condition called micropenis -- an erect penis of under 3 inches. Sometimes Peyronie's disease can reduce a guy's size.
Losing weight will reveal more of that hidden shaft that's buried beneath belly fat. It doesn't actually increase your size, but it will look that way...