You are fat, about 120 kg IIRC. I am fat and old, almost 100 Kg. Let's say my FTP for arguments sake is 350 watts. All is fine and dandy on the flats or rolling terrain, but when the road tilts up, you are with 4-5 to maybe 5 W/Kg riders. You and I get smoked. It is kind of simple, really. I need to lose 20 Kg and 40 years, you just need to lose 40 Kg.