This is a great question that has a couple of answers that are possible. You first need to look at your goals. Are you wanting simple weight loss or are you trying to reach a performance goal in a race? These two do not necessarily go hand in hand! Secondly what distance is your goal race if you have one? The difference between wanting to run well in a 5k and finishing an Ironman are worlds apart.
I did mention that you can turn off your fat burning metabolism but there is a flip side to this. Intensity is, with out doubt, the greatest and most effective way to stimulate fitness.. I would never dispute this. By ramping up intensity (defined in my mind by going beyond your MAF) you actually burn more fat (but a less percentage in regards to exercise time). This gets kind of confusing, I know! Training at MAF burns about 50% fat for fuel while training above MAF burns about 40% fat for fuel... so you could say that MAF burns more fat for fuel. But lets look at the math....
Let’s say you burn 100 calories in 20 minutes of MAF training (50 fat calories), and you burn 160 calories in 10 minutes of intense exercise (64 fat calories)... you still burn more over-all fat with high intensity exercise than with low intensity exercise.
Another positive factor with higher intensity is the increased metabolism for several hours after the exercise is done. A hard weight training session (the king of all anaerobic exercise) will ramp up your metabolism for up to 24 hours after the workout as your body tries to recover. You will have burnt a ton of glycogen and your body will have switched metabolic pathways- in essence teaching it to not use fat as fuel. After a few hours you will slowly revert back to fat burning.. but at what cost?
And here in lies the need to for you strictly define your goals! What do you want to teach your body to do best? If you're training for Ironman then it is imperative for you to be the most efficient at using fat as fuel. A 5k.. not so much.
The problem with intensity is the concern for the #1 factor in long term weight loss and that is consistency. There is nothing better for you than repeating exercises day in and day out.. intensity compromises this due to burn out, risk of injury and the law of diminishing returns- intensity stops producing results, and then you will back slide in performance, once you have exploited your physiological (lactate threshold and Vo2 max) limits.
To try and answer your question directly though- you are better off using a periodized methodology that will allow for long term health benefits. This would, in my opinion, include longer aerobic efforts to begin with (minimum of 8 weeks) in order for you to prepare your muscles, tendons, and metabolism to absorb harder training later. Then after you have adapted to the training and lessened the risk of injury you would add weight training and possibly some intensity, and also keep with longer aerobic workouts of ~1 hour or more at least 3-4 times per week.
On top of a well planned program you may try a very strict diet using an alkaline diet along with diligent food logging (calorie counting) at least for the first month until it becomes part of your life style.