Recently I've decided to amp-up my weight routine from once a week to several times a week and as close to an hour of lifting as possible.

Now what happens is that after a while of lifting, usually 40-45 mins (today it started at the 25 min mark) I start to gag while lifting. I get that gagging feeling in my throat, like if I'm going to throw up. I notice this only happens while I'm doing the lifting, it gets to the point where by the second rep I have to stop, and I usually have to end my work-out.

Does anyone know why this is happening and what I can do to avoid it?

I would talk to you're Dr. about this to get the correct diagnosis.

What are you eating before you lift? And how much are you eating on a daily basis?

Also what is your lifting routine?

I've been lifting in the morning after breakfast, which has been a bowl of cereal and a banana, and another fruit or two.

On a daily basis I am eating good, I don't count calories, but I don't let myself get hungry and strictly stick to grilled chicken, turkey, fruit, veggies, rice, healthy stuff basically and only drink water.

My lifting routine, (as of last week, before I didn't really lift much) is basically I alternate between upper body and lower body, and each of those days I try to do as many exercises as I can in an hour (though I haven't been able to go the whole hour) by using either free weights or machine, basically I move around rapidly all over the weight room working the designated muscles of the day.

Hope that helps....

Are you getting enough water? It could be a minor result from dehydration.

You could be eating too close to your workout. Your breakfast should be had about 2 hours pre-workout. If it's closer than 2 hours, try eating sooner and see if that solves the issue.

I would suggest eating more proteins too since you are lifting and everything you can afford the extra calories.

definitely drink lots of water

Also I know if youre not getting ENOUGH calories per day you can start to feel super sick..so maybe you need to be eating more

yeah would totally agree, would definately make sure you are well hydrated throughout your work out. i doubt it is anything to with the type of lifting etc that you are doing, something to do with food and water intake in and around exercise, and yes make sure there is some protein in that breakfast, after all that is the building blocks for muscle!

Also- if you are beyond your "noob gains" and are in a deficit and unable to build new muscle it will still aid in recovery of existing tissue.