From my experience light exercise is not harmful (to me). Heavy cardio and anything that would lead to heat exhaustion are the most dangerous. Also I should clarify that by "shoulder exercises" I mean shoulder motions that work the different muscles in the shoulder as well as some exercises with a resistance band. These "exercises" would be akin to physiotherapy exercises. I'm not talking about dumbbell presses. I think you misunderstood what I said or it was my fault for not being clear. Also, If I have some inflammation in my shoulder and fasting is known to be anti-inflammatory, wouldn't a combination of these exercises and fasting be a beneficial combination? Why would it not, I'd like to see the facts that your basing your comment on.