I am not anti supplementation. BUT, for the OP, having looked at some of his past posts before I commented, I note he is overweight, trying to lose weight and doing low milages, from this I conclude that IMO there simply is no point in supplementing, a basic well balanced diet would suffice. By this, I mean the food he would have to buy regardless would meet his needs (assuming he eats a half decent diet, which is a fair assumption if he is making a serious go at weight loss), the whey would be EXTRA, i.e. it would be additional protein above and beyond what is required and will have little to no effect and thus he can do without it and save himself a chunk of cash.
It is fair to say, he could get a low calorie serving of protein from such supplement's, so there is a flipside to supplementation. But it is still extra, most likely surpluss protein.
He says his legs feel fatigued, well maybe he just needs a rest! Fatigue is normal!