Not always true. I'm now 40 and still struggle to keep my weight up. Same as OP I have to consume a large number of calories throughout the day, eating every two hours.

If I let my guard down I slide back to 145 lbs within a few weeks and have to climb the mountain all over again. Age has yet to cure me of this.

Time is not exactly a friend. After 30 parent might have the opposite problem...

Not to mention 40!

I must say that the bends in the graph is very noticeable.