IMO, depending on your body size 200-400mg wkly will not induce deca dick. In other words someone 5'1 and 110 lbs may experience sides from Deca @ 400mg a week. Someone 6'4" 260lbs may experience no sides @ 400mg a week. Each situation is unique. I think the best approach is to start with 200mg and work up over a three week period to desired dose (say500mg wkly), and take note of any sides and decrease your intake accordingly. If you start to notice sex drive or testes go down at 500mg then drop to 400mg and so on. I think Deca Only can work well if you are aware of the sides and know what to look for and how to respond. Also (if needed) you may be able to regulate testes function with HCG during the cycle and toward the end of the cycle before you start Post Therapy.