A rowing machine can help you lose weight but to lose weight using a rowing machine you need to use the rowing machine at least once per day everyday for 30 to 40 minutes at a time.
Rowing on a rowing machine for 30 minutes per day can help you burn off 300 to 600 calories depending on your weight.
The longer you can use the rowing machine and the more often you use the rowing machine the more weight you can and will lose.
A rowing machine workout not only helps you lose weight but also tones your body too so it's a win win.