This phenomenon, sometimes called metabolic rebound, explains why the first 4 to 8 weeks after stopping are the highest risk period for withdrawal symptoms and rapid weight regain
Cleveland Clinic 2015)
Koksal B, Yildiz S, Ozgocer T, Yildiz A, Vardi N, Barutcu O
Furthermore, research concludes that it might mediate NO release, inhibit infammation and trigger the synthesis of growth factors
Both medications also help reduce food cravings and suppress appetite to assist with weight loss
I've heard good things about the results from MK-667, but the guys I know who have used it said it increased their appetite significantly - not the best for cutting, so I didn't use it