Cardio can help lose weight, but unless done properly, it will not burn fat. Fat is the bodies way of storing extra glucose. Burning fat and burning calories is not the same thing. To burn calories, you burn readily available sugars in an effort to turn that work into muscle gains. However if you are exerting maximum effort, your body does not look at the fat storage and see readily available glucose. Your metabolism doesn't burn fat the same way it burns sugars.
We both generalize our understanding based on our life experience. You talk about feeling pudgy... Well if that's the case your fat may not be stored as lipids and may still be a glycogen. I won't get into too much biological talk, as it is not my field of expertise either. What I am experienced with is losing fat stored as lipids that have sat on my body for at least a decade that I wanted to lose. Getting on the cardio machine and doing HIIT will not burn fat, per se. Sure you will burn calories and in turn even burn some fat given that your body may be able to tap into the storage, but it's not the most effective way. I was going an hour on level 20 doing HIIT and my body wasn't losing any fat until I started reading about the "fat zone". Once I was able to put the two together, I figure out what worked for me. It also made me be very aware of my heart rate and I was able to bring it down from 190 BPM to 125 BPM in about a minute during my interval training. I started to focus more and more on my heart rate and the energy I exerted during the time that I knew what my heart rate was. I still did HIIT for performance, breathing benefits, but I stopped thinking if I go on the cardio machine and burn 1000 calories, that I was going to burn the fat in my spare tire.
You want to lose fat? It's all about diet. The body will not use fat to burn energy when you are stressing it. In fact if you stress the body with little to no energy, the likelihood that your body stores fat the next time you eat is high given your body is in defense mode given you just starved it. But this scenario is for a fat person, not for the regular person. We are all creatures of habit and my body is the same. If it is used to over eating and storing fat, if I starve my body, it will store fat to avoid starving. The way to burn the fat is to eat less, not starve, while doing exercise that allows the body to dig into that fat storage (fat zone heart rate).
I have read a lot of medical journals on the subject. I am not the expert in all this, but this is what I have understood and practiced. Again this is for someone who is EXTREMELY overweight, like I was. I do not know what works for the body of someone who should be 180 lbs and is at 190 lbs trying to lose 10 lbs. I know that for me as a 300 lbs 16 year old, by the time I was 22, I was 215 lbs. Changing eating habits, regular workouts with cardio and weight training. It always depends on the focus of the person.
