i used to be on the slightly chubby side in my early teens, but i lost a lot of weight in my freshman year of high school when i joined the wrestling team, and i've been slim (to varying degrees of skinniness) ever since.

exercise helps, but the amount of exercise it takes to work off a single big meal is a lot more effort than just eating something else in the first place. i like cycling, but that's does more for overall fitness than weight specifically.

i think weight has the most to do with what/how much you're eating on a regular basis. i don't have a great diet, but i try to limit myself to one shitty meal a day, or eat only half of something bad at a time. i lost 10 pounds over the course of 2 or 3 months a couple years ago just by eating a yogurt for lunch during the work week instead of having a mediocre supermarket sandwich. of course, i've gained almost 10 pounds over the past year by eating out for both lunch and dinner more often. i'm 5'8" and ~140 pounds, so your mileage may vary.

either way, huevos rancheros over a corn cake with sour cream and sriracha: mmm...