In “Exercise Bologna” (a post on the Blog for the documentary “Fat Head“), Tom Naughton shows wrong the common idea that we need lots of cardio; describes the type of exercise we should get; then writes:
Here’s my theory on how it works: It’s not about the calories burned. Your body is going to put them back by making your hungry, reducing your spontaneous movement, reducing your body temperature, and/or some other means or combination of methods. (The 24 hour graphs of activity levels of overweight people on exercise programs are really neat – you can see their body compensate by reducing all other movement unconsciously. Of course the ass@#$% who publish this stuff – who are all thin – interpret this by telling these fat people that they need to exert more conscious effort to move more all day long.)
Its mostly about carbs and hormones. Your body has three energy sources – super-short, short and long term. For over-simplification all we care about is the short term – anaerobic glycolysis – that is the zone in which your body just burns carbs for fuel. Long term burns a lot of fat (not actually useful for fat-loss), and the super-short term uses up the ATP (energy) that your cells have on hand.
We want to do workouts that will drain the carbs (glycogen) out of your muscles. When we deplete your glycogen stores you will have increased insulin sensitivity for the next 36 hours (or your next high carb meal). Since body-fat is fundamentally regulated by insulin, if we can get your body to secrete less insulin for a day and a half, you will be leaner. (4-7)
Short bursts of intense exercise that exhausts you in the 30-90 sec range will maximize glycogen depletion, and thus body-fat lost.