Burning fat while Juicing?

Hey there is this really huge dude like 245lb and I don't see any fat on him at all. I asked him what he does for burning fat while he juices. He told me this: he said during the week He does no cardio he just eats and lifts. Then he said sat, sunday He will go first thing in the morning and do cardio for 2 hours at a really really slow rate for him I think it was around 119 or something not sure. I'm just wondering if I do this at this slow of a rate for 2 hours sat, sun if this will cut into my muscle supply while juicing. So for me I think my heart rate would be 127 I think. And I've done it for an hour before and I burn 700 calories x 2 this would be 1400 x 2 days would be 2800 calories. 3500 =lb of fat. So my question is basically can I do this at a really slow rate so it doesn't burn muscles and still be effective for burning fat. He said he drinks a protein shake 30 min before he goes but other than that he's on an empty tank and burning stored fat. Any of this make sense? suggestions please

If so this would work out good with my schedule

Well I'll soon be starting but from I eat now I can't get the calories in just plain oh food inless it has tons of fat, Id have to eat 10 cans of tuna 8 chicken breast, and so on to get the calories. How do you get the calories needed with out adding all the fat?

I don't like the idea of two hours of cardio. That is an awful lot to not go someone catabolic. I think you are better off doing like 45 minutes in the morning on an empty stomach four days a week.

Yah I know I need a foreman grill but the one I had started getting black shit in my foods lol. Time to take my grandmothers hahahah she don't use it no way. If you guys had to pick 1 food that had the most calories with out all that fat added what would it be.