Hi Sojo

A quick run down of macros

Protein is the building blocks of all tissue, including muscle. When you break down muscle by weight training the amino acids in protein rebuild the muscle. Many of the amino acids are known as Essential Amino Acids, which means we will eventually die if we don't eat them.

Fat is used for all sorts of functions within the body. Within the fats we eat are Essential Fatty Acids and without eating these will eventually die.

Carbohydrates are a preferred source of energy for the body. However, we have no absolute need for carbs and if we didn't eat them we might not be in the best of health but we wouldn't die through a lack of them. Obviously many vitamins, minerals and other micronutrients come from carbs, so it's not wise to never eat carbs.

Fat has no effect on your insulin levels, protein if eaten in excess and especially if that includes fast acting protein drinks can have an effect, but it is carbs that will almost exclusively effect your insulin, blood sugar and eventually stored body fat levels.

Therefore it makes sense to cut down or manipulate your carb intake when cutting. That's not too say you should cut them out completely but if you cut down and especially cut down on fast acting simple carbs you should lose body fat while maintaining lean tissue.

To keep energy levels maintained many people eat their carbs pre and post workout, which is when by increasing insulin levels muscle repair is assisted and fat storage minimized and maybe first thing in the morning when blood sugar levels are usually lowest.

You will definitely notice strength and energy levels drop if you cut carbs too much, so it's a case of you finding the right balance for your body type and daily routine etc

If you have four months to your comp then you have plenty of time put your carb manipulating plan into action.

Good luck and hope this helps