I lift and cycle. Recently went to a naturopath. At 6'1", 155lbs, body fat is only 8%. They say with every decade, a man should gain ~1-3% body fat. Ain't happening for me. My %fat in college was 12%, no doubt due to crappy eating and beer. I'm going backwards. He said metabolically I am an anorexic. I try to eat more, but my metabolism just ends up finding it's equilibrium. I'd love to put on 10lbs, but it won't happen.