You cannot out train a bad diet

With all the will in the world, if your diet is "wrong" then no matter how much exercise you do, you will never achieve a lean body.

Of course there will be those who say I've eaten (insert chocolate, fast food and alcohol - here) all my life and I'm not FAT. Maybe not, but what is your Fat to Lean Mass composition? More importantly perhaps - what do the blood tests say? How high is your cholesterol? Are you bordering on Diabetic? How good is your liver function? and a final question - How fit are you, can you climb a flight of stairs without getting out of breath?

It does depend what your goal is, but if you want to achieve a lean body (reduce your body fat / increase lean body mass) then you do need to ensure what you are putting into your body as fuel is helping you achieve that.