NEED HELP WITH WEIGHT LOSS

How often do you exercise? How many days?

Netting 500 calories below your BMR isn't going to be good for you. You're a young man and should be netting at least your BMR. My TDEE is similar to that and I am smaller and female (20yo female, 5'4", 62kg). I wouldn't recommend a girl my size eat 1336 calories, and certainly wouldn't recommend a taller, heavier male to do so.

Remember you don't need to feel hungry to be losing weight. Hunger is not a sign that your diet is "working." Try out 1750 NET calories and see how your weight changes. Unless you have a very different metabolism from the "average" person, you need to eat more

If you are up and exercising for 90min, 5 - 6 days a week....then no you are not sedentary.

Just remember Rome wasn't built in a day, so you need to give yourself at least 2 - 3 months of staying on point with your diet and exercise, to see the change.....
You will know if you are moving in the right direction in about 4 weeks....

If you are looking to do a race, then keep doing your exercise how you are doing....

But once you get that out of the way, I would highly recommend/encourage you to lift the weights.....
You can thank me later.

The way MFP works is it gives you a baseline number that in order to lose weight, you hit this.
And then you eat back calories you burn during exercise......

Similar to the numbers I gave you....only my calculation considers your exercise as part of the baseline number

So in the end you will be hitting around 2000 calories a day.....

Sorry I seem like a fool..
So should my net calories for the day be 2000,
Or should I be eating 2000 a day and burning let's say 300-500 off ?

Once it finish my c25K I'll bump up the weight training

Well your TDEE for the day is ~2500 - 2600
So if we go for that, then your total calories for the day will need to be ~2000

If you go w/ MFP, then you will want to hit 1700 plus whatever calories your burn in exercise.....which like I said in the end will prolly put you at around 2000 for the day.

I prefer TDEE for my calculations.

Since you are not doing a lot of weight lifting right now....
You can make it so that protein is ~0.8 gr / lb of body weight
Your fat can be 0.4 gr / lb of body weight (This is a minimum)
Your carbs can be whatever you like to make up the remainder of your calories.

Male, 18, 5 foot 6, 80 Kg
So my BMR is 1736 Calories
I'm really confused..
Say if I eat 1736 in a day, then burn 500 off at the gym, which leaves net at 1336, is this the right way to do it?
I've checked my TDEE and it's like 2100 calories, but that seems like to much .. I'm aiming for 1lb a week

In this case to lose 1lb/week you would eat 1600 calories (2100-500) 1336 Net is not enough for a male. When you calculated your TDEE is you used sedentary then you should eat 1600, plus eat back the cals you burned from exercise. Or you could set your TDEE to active, will give you a higher calorie goal, but then you wouldn't eat the exercise cals back as they would be included in your overal goal already.

say MFP gives you 1450 calories to lose 1 lb/week, and you plan on exercising 5x/week for an average of 400 cals per workout. well MFP will tell you to eat 1450 on the days you don't workout and 1850 on the days you do whereas a "professional" or TDEE calculator may tell you to eat 1700 everyday regardless if you workout.

So for the week MFP will have you eat 12,150 (1450*2+1850*5) whereas doing it the other way will have you eat 11,900 (1700*7) almost the same number of cals for the week (250 dif). The issue in not following MFP is if you don't workout the full 5 days or burn more or less than planned. If that is the case you may lose more or less than your goal, whereas MFP will have you lose your goal amount regardless how much you actually workout.

What many MFPers do is take the low 1450 and not eat back exercise calories which is wrong, if you are not eating them back then your daily activity level should reflect the higher burn with would be covered in the 1700/day above.

My routine is similar to yours, run 3 days a week and lift 3 days a week. I follow my TDEE - 20% and have my macros set at 40% carbs, 30% protein and 30% fat.

The only time I eat less is if I am truly sedentary (i.e. sick), then I will eat at my BMR plus some. I always try to net at least my BMR if not a couple hundred calories over that.

When you use MFP you eat your exercise calories back, when you use your TDEE you do not. That's about the only difference.