Originally Posted by kevin mckay
I think I read that in the fast five literature, but did not think that was the case? I know if sets you up do burn more fat than glucose but do not understand the mechanism?
Everytime you eat, if the meal contains carbohydrate, you burn that first before you burn any fat, either dietary or bodyfat. The carbohydrate in the meal will also set up a hormonal environment via insulin that will tend
to store fat and carbohydrate as bodyfat. Protein in a meal will trigger insulin as well, but also glucagon, so the fat in the meal doesn't tend
to be stored (as long as carbs are really low).
When you IF you go for much longer periods without food, fat burning is much more likely to be initiated, because intra muscular glycogen is usually only utilized during intense exercise.
Note that in the case of a long term low carb diet, this won't necessarily mean ketosis (in the 'producing and using ketones for energy after they have been manufactured in the liver'). It does however necessarily mean lipolysis (ie. fatburning) , which will come directly from FFA's in the bloodstream. Those FFA's will be from the fat in the last meal or mobilized bodyfat, depending on how many (fat) calories you are eating.
There is a widespread misconception that fatburning necessarily involves ketones. Getting the liver to first manufacture ketones and then send them out into the bloodstream for use by some energy requiring cell is not a particularly efficient way to provide energy for mitochondria. It's also IMHO not a particularly efficient way to use or lose bodyfat, because the enzymatic and hormonal pathways to be able to efficiently utilize FFA's directly (ie. become fully fat adapted) never get a chance to be properly established.
You might do better performance times carbo-loading, but you'll never be as healthy.
Is that a provocative statement or what?
In any case intermittent fasting will definitely encourage fat burning, but it may just be the fat and carbs (that you stored from the last high carb/fat) meal. Note that trying to beat the system by cutting dietary fat - the way the current medical/nutritional paradigm recommends - is a fool's errand too. Because you'll still store the carbs as fat. Which is why both the Fast Five approach, and the Warrior Diet - which both recommend eating high carb meals - suck in terms of optimum and hunger free bodyfat loss. You could just eat protein (and presumably enough EFA's) and not much of either carbohydrate or fat and just force your body to burn bodyfat. But it's a bit boring.
The other thing about becoming fully FFA adapted with a long term highfat (once you've reached your bodyfat goals)/ mod protein/ low carb dietary approach is that your body effortlessly mobilizes and uses (directly, not through the ketone intermediary) dietaryfat and the considerable amount of internal bodyfat reserves (inter organ fat - the stuff that there is still plenty of, even when the love handles are history
Anyway that's been my personal experience with nearly four months of very low carb 15/ 19 hr daily intermittent fasting, after four years of VLC at least three meals a day. High fat (high sat mono/ low PUFA's -except mod Omega 3's) low carbing with normal meal frequency was I thought about as good as it could get nutritionally. But low carb IF'ing has taken nourishment to a whole new level.