Fun and diet effect

I habde the tower now almost a year and am very satisfied. My cats find it still interesting and it is also only one time been overturned. However, the cats learn this: now is shaken off, so what falls out.
The diet effect I see in my overweight cat: you can no longer loops like crazy, but have to work every single piece of kibble. Anyway, I like to think that they no longer by eating as much and possibly also decreases time soon ..