As far as workouts go, you can try anything as long as it's not too intense and adversely affects your body. But the workout that you have specified here is actually one that people use to gain weight and not lose weight! The three day workout is a very popular workout that bodybuilders indulge in three times a week, so as to pack some muscle and to tone their body. It's hard to lose weight under this workout. There are three day diets for losing weight, but these are also not very good options and they'll result in some drastic weight loss.