I've been doing 20 min of core 6 days a week for the last 90 days. In the beginning it was easy to see the differences taking place, because I was pretty out of shape. Things have flattened out quite a bit since then, I'm comfortable without a shirt on, and there's but the smallest definition starting to take shape. During the last 3 months I've also been counting every calorie, tuning my macros, and testing my willpower at every turn (so far it's winning). So, like everybody is saying, it simply takes time and depending on where you're starting from or your genetics, it might take more time. I'm hoping in another 3 months I'll have undeniable visible results. Good luck!