Mighty Morphin Power Rangers...

First things first, to fuel yourself you need to know your body type, everyone bandies about different terms but there are three generally accepted terms (I've simplified them in my own unique way) and note that you may fit a composite of two types instead of neatly into one:

• Ectomorph: normally small framed, with light muscle structure and finds it hard to gain weight.
• Endomorph: large frame, good muscle structure and gains weight more easily.
• Mesomorph: large frame, gains weight easily and less defined muscle structure.

Now, you Endomorphs and Mesomorphs are jammy gits, I hate you, pretty much anything you do to your diet will result in your body coping with the training.

Ectomorphs find it difficult to gain weight if at all. Normally upping your calorie intake by 1000 to 2000 calories a day should suffice.

You need to make sure you are eating the right foods though, 1000 cals of fat is going to harm anyone that eats it. If you need to train and need to gain weight then you should increase the carbs dramatically, and up the protein too.

Another trick I have is to snack at night, your body will normally still digest whilst you are asleep (somewhat slower) but you are expending far fewer calories; pack away some simple carbs and protein before bed and you will gain weight and be able to train properly without risking muscle fatigue as much.