Losing Weight while Building Muscle

You're not going to build muscle eating 1200 - 1500 calories per day. Building muscle requires a surplus of energy (calories) and proper routine. You can cut fat and preserve muscle mass by lifting and taking in proper protein but you can't really build any appreciable muscle while you're in a cut (dieting)...essentially, you cannot be in both an annabolic and catabolic state at the same time.

You can eat to maintenance and lose fat (slowly) and build some muscle (very slowly)...but it's really, really, really slow. This is why most people go through cutting and bulking cycles to build mass and then cut fat...when you bulk you inevitably put on a little fat.

1200 - 1500 calories may also be too aggressive of a calorie deficit for you depending on your stats and how much fat you have to lose...too large a deficit is going to actually burn muscle mass despite your lifting. I'm 5'10" and oldish and took in about 2100 - 2200 calories per day to lose about 1 - 1.5 Lbs per week...I maintain right around 2800 and bulk good at around 3000 - 3100.

Edit: also, don't skip leg day...even better, drop the bro split and do a proper 3x weekly full body routine. I'm assuming you're a beginner and you're going to get far more benefit from a full body routine utilizing free weights and focusing on compound lifts than you ever will with your split and doing a bunch of isolation work. Down the road you can add some assistance work (isolation lifts to improve your big compound lifts) and eventually determine if you need to go to an actual split routine...which I've found to not really be necessary unless you are an advanced lifter and/or competitor.

I weigh 151 pounds and have a body fat percentage of about 17-18%
My Metabolic Rate is 1700 calories per day
So I understand I need to do 1 at a time but which one should I do first build muscle or lose fat?

Are you talking about your Basal Metabolic Rate (BMR)? That is the amount of calories your body would burn just being alive if you did nothing but sleep all day.

What are your stats (male/female...height, etc), I have a hard time believing your actual TDEE would be 1700 calories. My BMR is about 1800...then I need my calories for day to day activities...and then my calories for exercise activities...and then I take my cut from that when I'm trying to lose....and I'm pushing 40.

If you're at 17 - 18% BF you're going to have to cut really slow...shoot for about 1/2 Lb per week or so. Most people cut to around 10 - 12% before bulking to allow for the longest possible cycle without having to cut again.

I'm in the same boat right now. But I know cutting fat is my primary goal. I do lift and cardio, but not concerned about gaining muscle in this phase. Tho it would be nice. I also eat between 1200-1500 cals a day and yes this may seem extreme. But it works for me. When I get to ~15% body fat which is around 185 lb, then I will transistion into a bulk phase where I will be eating at a surplus and will increase my lifting.

I know in my bulk I should do less cardio or drop it completely. But I got addicted to the jogging and was thinking about doing a 10K this spring. So I will want to continue to train for that. To me that just means I will have to eat at even more of a calorie surplus if i want to bulk up.

But main thing you will want to consider especially if you are lifting and eating at a significant calorie deficit. Get your protein in. In fact, more than what mfp says. About 1 grams worth per pound of lean muscle mass you have right now. This most likely means that you need to eat over 100g of protein every day. This is a huge challenge for me to accomplish since I eat only between 1200-1500 cals. Not only do i need to eat protein, but get enough in the important micros like potassium, Vit A, C, D, calcium, iron, ect. What I did was cut back on my carbs in the form of breads, pastas, wheat, rice. I still eat some whole fresh fruit (carb), lots of salads and veggies (carbs), cheerios or oatmeal (carb), and every so often a sweet potato (if I am low on potassium or Vit A for the day) (also a carb).

It's all about balance and finding your rythem for what works, and patience. Rome was not built in a day.

But my suggestion is to worry about burning the fat and try to maintain your muscle mass as much as possible. Then when you get to a happy BF%, then bulk up. Then you may find yourself that during the bulk that you gained some unwated BF%, so you go into a cut again, then back into a bulk, and so forth. That is why they call it the cycle.

http://body-improvements.com/2013/09/04/can-you-build-muscle-and-lose-fat-at-the-same-time/

http://body-improvements.com/2012/08/22/qa-how-can-i-go-about-building-some-muscle/

Buy Tom Venuto's Book - Burn the Fat Feed the Muscle. Great book, great programme and fabulous for anyone who wants to be leaner or look sexier. Or go to his website and read his blog and articles.

The above reference to Martin Berkhan - LeanGains, another good guy, great reading.

My experience: I have lost 20% body fat and 30kg in the last year. I didn't gain any muscle but I only lost about 3kg of muscle, which is a fantastic result and I achieved what I set out to achieve. Of course, I was eating at a 20% deficit, and you can't really gain muscle on a deficit.

Quite frankly I dont think you are eating enough - my opinion.

Eat like the leanest people in the world. 1 gram of protein per lean lb. of body weight. Train hard 3x per week with these 7 lifts: Bench, Standing Row, Dead Lift, Bi-Cep Curl, Tri-Cep Extension, Military Press, Squat. You can also try to cycle your nutrition. 2 days of lower carb. / calories for fat burn (500 calorie deficit) followed by 1 day of higher carbs. and calories (same days you lift) Through this program I am able to take my body fat down from 15% (off season) to 11%