Here, I googled this post for you from Lyle Mcdonald, who literally wrote THE book on ketogenic diets, "The Ketogenic Diet". Even he admits no real advantake of keto diets over other sensible diets (adaquete protein, EFA's, etc).
"changing RQ doesn't change metabolic rate, it changes the proportion
of fuels used. Let's say we have two people with a total daily energy
expenditure of 2000 cal/day. The first has an RQ of 1.0, the second 0.7
(I'm using extremes to make the math easier).
The first person is burning 100% carbs, 2000 cal/day, 500 g/day, zero fat.
The second person is burning 100% fat, 2000 cal/day, 222 g/day, zero carbs.
That's ignoring the small contribution of protein, of course. Assume
it's the same for both and not worth worrying about.
So this comes into play with fat balance which is simply the difference
in fat burned and fat eaten. That is
Fat balance = fat oxidatin - fat intake
A positive fat balance means you're gaining fat; a negative fat balance
means you're losing fat.
So take our RQ = 1.0 person. Any fat they eat will be stored. That, of
course means, that they are eating >2000 cal/day (i.e. they are above
maintenance levels). Let's put them on that diet, zero fat and 500
g/day of carbs. They are in calorie balance, no net gain or loss of fat.
The RQ = 1.0 person can eat 222 g fat per day and not gain fat.
Anything over that and they will, which means that they are eating >2000
cal/day. So put them on that diet, 222 g fat per day and no carbs.
They are also in calorie balance, no net gain or loss of fat.
so let's take 500 cal/day from each person. The first guy will reduce
carbs, the second fat. Protein is the same for both.
the first person's RQ will actually go down to reflect the difference
and fat oxidation should make up the difference. So for a 2000 cal/day
metabolic rate, they are burning 1500 cal/day from carbs and 500 cal/day
from fat (55 g/day). They should be losing 55 g fat per day.
The second guy's RQ is already as low as it can go so the difference
will simply be fat burned - fat intake. A 500 cal/day reduction = 55
g/day. They will also be losing 55 g fat per day.
And this really explains why diets of varying composition but the same
calorie level tend to result in the same fat loss. On the higher carb
diet, you're burning less fat, but you're also eating less fat. On the
lower carb diet, you're burning a lot more fat, but you're also eating a
lot more fat. So the end result ends up being about the same. Of
course, there are a lot of ASSumptions in there: such as exactly
controlled calorie levels which gets into a host of other factors.
I hope that makes sense,
Lyle"
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