Guys have faster metabolisms and it's easier for them to lose weight. Also, when he's "working out" is he doing weight training? (I'm guessing he does, cuz that's a manly workout LOL) If so, THAT is really upping his metabolism even more. YOU could do the same.
The more muscle you build, the more fat you will burn, even when at rest.
Women, without steroid help, simply can't "bulk up", you will get toned and sexy looking even lifting HIGH WEIGHT with low reps.
Here are my first pictures posted last year from when I started weight training...just 6 weeks difference between the befores and afters.
http://www.atkinsdietbulletinboard.c...ad.php?t=28045 (Six weeks of weight training before/after)