I really wonder if there is a reduction in metabolism with age. I ask because when I was younger (50 yrs. ago...now 71) I read that to determine your daily caloric intake you should multiply your target weight (current target for me is 180 lbs) by 15. FWIW, this is exactly what is suggested on a site posted here. This includes a factor for (in my case) moderate activity. I used moderate activity because it sort of fits and I ride about 30 mi./day 3 days/wk. So, for me 2700 cals a day. At this moment I weigh approx 187 lbs. I count calories and can guarantee that if I eat 2700 cal/day I will gain weight.