Marasmus is a condition involving both severe protein deficiency and markedly inadequate intake of calories.

Kwashiorkor is a condition involving severe protein deficiency, but in the context of sufficient or only mildly deficient intake of carbohydrates and calories, overall.

Fat is high in calories; you don't need a lot of it. Too many calories from any source can make you fat.

Spin Class is intense if you dont slack off you could potentially burn 1000 calories in an hour!Elliptical machine is great too... the best way to burn calories is to create a routine involving different cardio work outs to get the best results... along with a good low carb diet plan!

involving how?

No, Digesting calories is taking in calories, Burning calories is working off calories.