Working out with a bad diet is like trying to gain muscle when you eat chocolate only, it simply will not work. You need to eat correctly if you want to see results. The only way that you will get any noticeable results from all your hard training is to eat correctly.
High intensity interval training or HIIT has been conclusively proven to work in many different studies done across the world. Sports science has now proven that the only way to get decent results is by training with a high intensity. It has been shown that you need to train using HIIT for a maximum of 45 minutes and no more.
But it is a lot more than just training correctly as you probably know. If you train at exactly the right pace and at the exactly the correct intensity you will more than likely not get the results that you are looking for by simply not eating correctly.
Good Nutrition is the basic building block that you need to build muscle or hypertrophy on long term basis. Without good nutrition your body will be forced to make up for the lack of amino acids required to adequately repair the muscle damage that you caused during your workouts.
It is all a delicate balance that you need to achieve muscle growth. The correct combination of water, sleep and nutrition and training is all set up in a very specific balance that is specific to you. It takes time and dedication to get larger muscles but it simply cannot be done without eating correctly.
Eating a ‘bad’ diet generally means that you are getting poor quality calories into your system. What that means is that you are eating simple sugar like fries and burgers which will raise your sugar levels, release too much insulin and make you store fat.
But worse is when you damage the muscle during an intense workout and your body is unable to find the required enzymes that it needs to repair the muscle. This will result in what many bodybuilders constantly keep a careful eye out for and that is over-training and reaching that dreaded plateau.
You will reach a plateau when you stop getting stronger no matter how hard you train because you simply do not have the required nutrients in your blood stream to fix the damage. Your body then goes into a self-protection mode where it makes sure that you stop any farther damage that you are causing.
So the answer to the question about whether you can exercise on a bad diet is that you can certainly exercise when you are eating incorrectly but it will eventually catch up with you. If it was that easy to gain muscle then everyone would have loads of muscle on them.
If you are currently training on a bad diet then you need to slowly teach yourself the required skills so that you can increase your productivity from those hard workouts that you do. It is a learning curve that constantly needs updating as you learn more and more about how your own body responds to exercise.