What I mean by this is to get the best results you need to be consistent in your workouts.
Take a time period, I like 6 weeks, and be consistent on your workout sets, for example 3 sets of 10 reps.
But each workout change some specific part of your workout, maybe change your resistance, or change your time between sets, or the order of the exercises.
After 6 weeks, it's time to change your training variables.
You could change your workout sets to 4 sets of 6 reps and use heavier weights and longer rest periods between sets.
You may also at this point change your training program.
For example, if you are doing flat bench presses, change to incline or declined bench presses, change bent over rows to upright rows etc.
Once again, make sure that each workout you are changing some specific part of your workout.
Another exercise variable you might want to include in your workout program would be super-sets and circuit training.
Super-sets are different exercises done in pairs, for example( bench press and squats then rest).
Circuit training involves doing your entire workout routine one time, rest and doing it again.
It's also important that you are tracking the progress that you are making, be sure you are writing down weights used, reps done, and number of sets completed.
When you see you have hit a plateau, it's time to change up your variables once again.
Try this routine and after a few months of working out, choose 6 sets of 6 reps but group your exercises in tri-sets ( three exercises performed back to back to back) doing your entire routine one time through before resting.
Of course the other part of the equation is that you must be eating healthy, whole foods to lose fat while you gain muscle.
I hope this gives you some ideas on how to add both consistency and variability into your training programs and helps you lose fat and gain muscle.
You can get your copy of my free fat loss report here