The best advice I heard a long long time ago was you can't out train a bad diet. You can work your ass off in the gym, but you don't see the results. More then likely it is because you are eating like shit. You are only doing half of what needs to be done. You have to fuel yourself with the right food and the right amount of food in order to provide change to your body. Now for some people, mostly younger individuals, you may not have this issue yet. But trust me, your time is coming, age catches us all and you will too feel that double pound cheeseburger in your ass one day.
In our line of work it is very difficult to eat the right way all the time. The easiest and most effective way on the job diet tip I can give you, is track your calorie intake. Now a days it is easier then ever, smart phone apps make tracking your food easy and it works if you stick to you. My food dairy app offers tons of features and it is a great tool to help you get started. The company does charge a small fee per month, but you can cancel at anytime. Also you can try for a week to see if you like it.
Another calorie app is my fitness pal. I have used both, and I would suggest using the my food dairy app if you are just starting to get back in shape and you need extra help doing it. But if you have a pretty good handle on your diet and want to just lose a few pounds, my fitness pal will work.
Check them out and give it a try.