How long should a workout be to lose weight?
The way fat loss works is that muscles are put under stress doing sets with repetitions. The last ‘rep' should completely tax your ability to complete it.
You breath often and hard, because your body needs oxygen to use up glycogen and fat stored energy. The ‘exhaust' is water vapor and carbon dioxide.
During the next 48 hours those muscles are ‘repaired' using up more fat energy to build muscle. More H2O and CO2 expelled - especially at night.
Along with stressing the larger muscles (below the belly button) a diet that has no white foods,( e.g., alcohol, sugar, bread )and fewer carbohydrates, more protein and little fat should be consumed during the day. 6 smaller meals of equal calories that total to your base metabolism plus 10% let your body know that it is not starving and maintains higher metabolism.
You need food so that you can perform your ‘exercise'. If at the end an hour (or so) you have enough energy to do aerobic activity, then you should be working harder moving the weights around during your exercise time.
If you don't have the energy to do your planned exercise, you need more food in order to complete your program. The main reason to eat is so that you can do your exercises. If you are hungry during the day increase the protein. You know you are consuming too much protein is that your work-out clothes smell of ammonia.