Milers can be big, strong people. Steve Scott weighed 165-170 at 6'1" when he ran 3:47! He had plenty of wins over Coe, Aouita, and the rest of the world's best 130-pound men. Walker, McMullen, Van Damme, Mottram...there are a lot of world-class guys who weigh considerably over 150. Yes, they're taller, but also proportionately heavier. People like Ovett, Webb, See, Batty, and lots more probably weighed 150 or more when they ran way under four minutes. (I think Erin Donahue ran about 4:22 weighing about 150, didn't she?) As for running 4:30-4:40, well, Allan Just ran a 2:18 marathon at 5'11" and 180, so there's not much chance that a 5'10"/150-pound runner's mile ability is going to be limited by weight. And as for cutting sugar to lose weight in high school, I hope the warnings already on here are enough to dissuade any serious runner from doing that.