Want to lose weight? It all matters on the diet, if you want to gain weight it also matters on the diet. So what's the difference? On training days depending on what your goal, for instance if I'm trying to bulk up, my reps would be low but my weight would be high, if I'm trying to get lean/cut I will up the reps with lesser weight. To be honest I just did every rep till failure and followed a Kris Gethin plan that helped me through the training.
I will link a crazy program that I actually did, you can either choose to do it or choose not to do it, it's all up to you.
http://www.bodybuilding.com/fun/kris-gethin-12-week-daily-trainer.html
Now while on this program I highly recommend that you take a look at the supplements that will be included in the 12 week plan, with these supplements you surely wont lose as much muscle mass, and the recovery rate is faster in my opinion. (Depending if you're bulking/Cutting)
Supplements I took while on the Kris Gethin plan
Green Tea
L- Glutamine
L- Carnitine
Optimum Nutrition 100% Whey Gold Standard™ Vanilla Ice Cream
I didn't take BCAA's until about after the plan and I started creating my own workouts
If you aren't satisfied with the training or you just don't take it serious, I recommend just creating a plan that suits you. If you are trying to lose weight I would look up the Paleo Diet, I've done this for a few weeks for my MMA and it helped ease my mind and I saw results.