Perceval said:
Correct me if I'm wrong, but one thing I haven't seen discussed here is precisely how much fat versus protein should be consumed. If we were to try for a 70% fat, 20% protein and 10% (or less) carbs, how many grams of fat and protein work out to? I presume it can't just be worked out by weight alone because we are talking about energy requirements here and I understand that fat provides much more energy than protein.
For example, if I eat a pork chop that has 20% fat and 80% protein as weight on the actual chop, what might that work out as in terms of energy?
I think it hasn't been discussed because it's complicated :) You have to switch from the weight of the food you're eating to the calorie content. And you're right - fat is more energy dense than protein or carbohydrate.
Let's suppose, for arguments sake, that you're eating 3000 calories per day (calories being the measure of energy). If you're aiming for the 70% fat, 20% protein and 10% carbs you mentioned above, that's 2100 calories of fat, 600 calories of protein and 300 calories of carbs. When figuring out how much that translates to in weight, we need to convert calories to grams. But, while protein and carbs both provide 4cal/g, fat provides 9cal/g.
This means you're looking at 150g of protein, 75g of carbs, 233g of fat.
A single pork chop has about 33g of protein so if it was 20% fat you're looking at a 41.25g pork chop with 8.25g of fat. That means you're getting 132 calories of protein and 74.25 calories from fat. In other words, not enough fat.
An easier way to figure it out may be this - since we know how much protein and carb we're aiming for, roughly, we can just say "make the rest fat". We know we're aiming for 72g of carbs (288 calories). We know our protein requirements are anywhere from 1.2 - 1.7g/kg body weight (from Courageous Inmate Sort's article - great article btw :) ) . In my case, I think I weigh about 86kg (give or take, I don't own a scale), so that means my protein requirement is anywhere from 103 - 146g per day. Let's take the middle ground and say 130g (520 calories).
So we could just say eat 72g of carbs, 130g of protein and eat the rest as fat until you're sated. Or you could figure out your ideal caloric intake and calculate how much fat you actually should be taking in, but these calculations are always problematic and theories on ideal caloric intake are usually slanted towards the "lower calories is better" idea.
Assuming, as I did above, eating 3000 calories (which would be too much for most people, but we'll just go with this since I think it's probably right for me), with 808cal taken up by protein and carb, I need to hit 1192 calories of fat - or 133g of fat per day. That's about 1/2 a pound of butter per day worth of fat, ie. a whole lot of fat. I really don't think I'm hitting this and have actually been running into issues with heartburn when I up my fat intake too much.
I don't know if this helps at all. I may have just confused the issue. There's quite a bit of wiggle room in the formula here considering protein requirement is given as a range. At the end of the day, I think most people are just going to eat what they feel like after keeping their carbs down to 72g, but maybe we should always be trying to make an effort to load up on fat.
Legolas said:
I think so too. As far as I understand different organs are using different energy, for example the heart needs fat (what Dr. Lutz describes) and the brain mainly sugar (carbohydrates, p. 69 in the book), so I don't know if a no-carb transition phase is possible or even recommended. Maybe these athletes don't need the brain. :P As Laura wrote some posts before and mentioned by Courageous Inmate Sort, it is better to go easy with the diet and give the body time to adjust.
It is possible, Legolas, because of something you wrote about earlier in the thread - gluconeogenesis. The liver is able to convert protein into carbohydrate in order to feed the brain and other tissues that can't survive on ketone bodies alone. Theoretically, zero carb should be doable, as long as you're getting vitamin C from somewhere.
