Andrew
I am going to make some assumptions, many could be wrong but they are common beginners issues most of us will have made some of, self included.
Not understanding how much body matter weighs. Most will know that muscle weighs more than fat, few really appreciate why or how much. Muscles is around half water, and that is seriously heavy stuff, fat is actually very light. So gaining 7 pounds of muscle and losing the same of fat will see you becoming a lot smaller. Really low tech way of seeing how much of a difference there is put some trimmed fat and lean meat in water and see how much fat there is above the waterline compared to the lean meat.
Not varying training. I did the same first workout for years as a child, my reward was getting really good at those movements, I looked the same and gained nothing else. Exercise is about overload, and to do this you need variety. I tend to recommend changing weight sessions around every 2 months (8 weeks) for maximum benefit, the exact time is personal. Aerobic training is something you can shuffle as often as you like as this is at a lower intensity and usually lower risk, usually.
You are going for a varied program, which is good, but I would say the 2 hours weights will be very low intensity based on the 2 hours. At 17 and 6'5" you are likely to have finished most of your growing so can start upping the anti on the weight training, doing more in shorter sessions, check out
http://training.fitness.com/young-athlete-development/young-athlete-development-program-50627.html by Goldfish, one of our best generic trainers.
By shortening the weights sessions while increasing the intensity, which will burn more energy both during and after when recovering, you will free up time for more cardio work. There are people who will declare low intensity static state cardio doesn't aid weight loss, this is incorrect, doing only low intensity static state cardio will make weight loss very slow, but as part of a varied program this is a very good system. You are doing sprints and mini circuits now to cover the interval/ circuit level intensity, so with an increase in high intensity and static state you will be making your body work in all levels, making it burn more energy and see all muscle as too valuable to consume. Vary what you do as much as you can, biking, steps (electronic or real, jogging, rowing, walking swimming.
The big one you haven't covered, diet. There is a good reason the first three letters of this spell die, get it seriously wrong and you will kill yourself. I don't know what you eat but my normal system is to recommend the 10% diet, eat exactly what you do now but 10% less, normally combined with `10% increase in activity, but that has been covered. Unless you eat 5 pounds of lard, sugar or meat a day don't start looking to cut things out, just eat normally and slightly less. Burning more energy will aid burning fat store, but if you have increased your intake to compensate this won't help.
Realistic expectations. 10 pounds in over 6 months is slow loss, but it's still loss and there is a way to put the loss into perspective below, also take note that this is assuming you haven't gained an ounce of muscle which is unlikely.
1 pound fat = 3,500 calories
Minimum daily requirement for someone your size = 2,000 calories
10 pounds lost = 35,000 calorie deficit
35,000 calories = 17.5 days minimum intake
So you have burned the equivalent of not eating for 2.5 weeks, assuming no muscle gains. This isn't the fastest loss but be sensible and see this as a success.
The danger zone. People see weight loss at great and faster as automatically better, don't. Below is an illustration of the reality of quick losses and what follows assuming the diet is actually sensible. In most cases the diet is far from sensible but this is something to be thinking about.
Energy consumed daily = 2,000 calories, well balanced, high starch, sensible protein (not high), low fat
Energy burned daily = 2,500 calories, due to training
Daily deficit = 500 calories
Weekly fat loss = 1 pound
First week weight loss = 5 pounds
Water loss = 3.9 pounds
Lean mass gain = 0.1 pound
Second week weigh gain = 4 pounds
fat loss = 1 pound
Water gain = 4.8 pounds
Lean mass gain = 0.2 pound
The lesson here is know what you are burning and eating. If you know the scales are showing a loss that is way beyond the deficit of fat, it's water, and the weight you lost will be found very soon. Being mentally prepared for this helps. The 5 pound loss above would required a 17,500 calorie deficit, the amount of food you would be burning in 5 days so unless you knew you had burned a full weeks food while consuming 2 days worth (stupidly dangerous) then much of it is water.
The maximum weight loss you should ever aim for is around 2 pounds a week, this requires a 1,000 calorie a day deficit and is treading the line toward starvation zone. 1 pound a week is impressive because this is 500 calories a day continuous deficit. Truth is if you are training and dieting over a long time and losing anything this it good news, steady losses tend to stay gone far more often.
Liquid diet. I am referring to the most commonly ignored areas of calorie consumption. People will happily sit with their friends over their 4th or 5th pint complaining how they can't understand why they cant lose weight they barely eat a thing. It would be more funny if I hadn't seen it so often.
