Is it normal for a male's body confidence and self esteem fluctuate?

It seems like every day, I either feel super sexy and on top of the world, or that I'm just a fat loser that'll never get a boyfriend. I'm not sure why, because I'm not even that much overweight, maybe 10 or 15 pounds, and people always say that I'm not even that fat or unattractive. I've always been really harsh on myself and put pressure on myself in almost everything I do from academics to video games. I guess having these extremes about how I feel about my body is part of my personality?