In a word, NO. Everybody is different, so for someone starting out this would be ideal as there is not a lot of effort so pretty much anything they do will help to burn excess fat stores.

To work off your fat burn, you would need to work out to a percentage of your maximum heart rate or VO2 max.

You would need to go to a proper physiology laboratory to get these values.

A better way to embrace 'aerobic respiration' is through bodyweight exercises. i.e. walking/running, callisthenics (press ups, squats etc.)

You need to condition your body to metabolise fat over protein. You do this by working at the lower end of the heart rate scale... what these so-called trainers say about high intensity intervals is just a quick fix so they can basically get clients in and out and bolster their results.

However, its true that Rome was not built in a day and anything you take your time over is worth it as it normally takes time to break it back down.

220 - age is just a generalisation, so if you are going into something as what is considered any type of athlete i.e. amateur, casual, elite whatever, then do a maximal test yourself.

Its bloody hard work, I could not do anything and was completely wiped out as I then jumped into the sauna!!! Get yourself on the treadmill and start off at a moderate pace. get up to your race pace then every 2 minutes take the incline up a degree. Do this until either you cannot continue (you need to push yourself to the limit) or until your heart rate does not increase after two consecutive readings.

From this you can use either heart rate reserve (Karvonen) or a percentage of your MHR. experiment and see what suits you best. I personally prefer Karvonen as it takes into consideration your fitness at rest too.