KD,
I wish I had all the answers but sadly I don’t and neither does anyone else. Most of your concerns seem to be around athletic performance and since I never was an athlete I can’t really say. I’m also a few months shy of my 60th birthday so peak performance is not something I’ve worried over for a long time. I’m far more concerned with getting out of bed every morning and/or getting the trash cans to the curb on trash day without throwing my back out or otherwise injuring myself.
Q1: There is a big difference as to how the body responds to everyday energy demands and how it responds to maximal effort type activities. I have no experience in this area so really can’t comment beyond my general observation that most people that I talk too say that if they convert to a fat based metabolism they increase endurance but sacrifice brute strength. Though I’ve never been a weight lifter or especially strong, I can say that on my current diet I can easily run long distances even though I’m not a distance runner and don’t train, but flag rather quickly doing high intensity wind sprints. Is there a middle ground? Lyle McDonald seems to think so. He champion’s a Cyclic Ketogenic Diet for athletes and feels that this provides the best of both worlds. I’ve read his work and it seems to make sense in context with my experience. It’s just way to complex and adds nothing of value to the kind of lifestyle that I want, however, it may be just the ticket for you. Just do a Google search on Lyle McDonald and you’ll find everything you need.
Q2: Well I thought this way too, but found that there seems to be more to the problem than would first appear. My experience has been that my BG hangs right at 100 no matter what I do. My doctor was a bit concerned because BG seemed high, especially when not eating any carbs, but we reasoned out what we THINK is happening. I eat about 100g protein and 225g fat per day. This provides about 2,400 calories with 83% of calories from fat. If 60% of the protein was being converted to glucose, this is still only 60 grams and yet my BG is always at 100. I tried reducing fat and doubling the protein to see if BG would rise, yet BG stayed rock solid at 100.
Here’s what we think is going on. My body uses fatty acids as its primary fuel. Most tissues are rejecting glucose in favor of fatty acids. There are a few tissues that need glucose but their demands are very small, and the conversion of protein as well as the conversion of the glycerol in the fat triglycerides in my diet provides far more glucose than my body needs. Since most all this surplus glucose must be manufactured from non carb sources, there is no massive BG spike when I eat. Instead, proteins and triglycerides are slowly broken down in the liver over several hours and the glucose created is gently and slowly released into the blood stream. Since there is no large fast BG “spike” from carbs, my body responds to the slow rise in glucose by releasing insulin very slowly to just counteract the gentle rise – hence BG stays stable at the high end of the “normal” range. With BG in the high range the body thinks there is plenty of food so it makes no effort to conserve energy. This same effect causes people following a VLC/ZC diet protocol to appear to be diabetic or insulin resistant when given a glucose tolerance test because their pancreas is no longer primed to pump out huge amounts of insulin several times per day to deal with massive BG spikes. If we start eating carbs again, the insulin response will return after about 3 days of high carb input. Most of this information can be found on Peter’s Hyperlipid Blog.
Heavy carb eaters often have the opposite BG curve – their’s hovers at the lower end of the range. Using the same reasoning as above, a carb eater consumes a meal high in carbs with a very large gylcemic index (rate that the carbs are converted to glucose) when compared to protein and glycerol conversion. The glucose spike is large and rapid. The body is not designed to efficiently respond to large rapid BG peaks as blood circulation takes time so the effect of insulin is not detected instantly. This causes the body to overshoot the glucose spike with too much insulin and BG plummets. If it goes too low then the body will start releasing glycogen stores and/or sacrificing tissue to be converted by into glucose to keep BG levels in a safe range. BG will now stay at the lower end of the normal range as the body will only release glycogen or convert tissue as necessary to maintain a minimum level. It doesn’t know what caused the low BG and will reserve energy stores in case food is scarce. It’s job is to conserve energy and you’ve fooled it into thinking times are lean and you are starving. You will also most likely crave something sweet which the body has learned will get you to drink a sugar drink or eat a candy bar and, if you do, the whole yo-yo starts over. BG spikes, insulin dumps and overshoots, BG rapidly falls, body reverses and starts releasing stores to keep BG up, and you crave something sweet.
Q3: The issue is intensity vs endurance. It seems that muscles do respond to glucose and fatty acids differently. Glucose fueled cells seem to be able to provide greater intensity (lift heavier weights, wind sprints, etc) where fat fueled cells seem to be able to sustain moderately high energy output (running, moving moderate weights for long periods). Phinney did a good bit of work on this as well as McDonald mentioned above. I don’t lift weights or do any other exercise for the sake of exercise as I feel it is a waste of time. I prefer to spend my time in my shop making and repairing things, so if you want to know how diet affects athletic performance you’ll have to go somewhere else.
Q4: Time frames will vary with the individual as well as what dietary protocol they choose to follow. There are as many variables as there are individuals. People will often say that they are doing something that they are not truly doing and that just makes more noise to filter from the data – not an easy task. People may not knowingly lie to you, but they may lack experience or knowledge to the point where they believe something that is not necessarily true, and provide inaccurate information.
I’m by no means perfect and if you’ve read my journal you’ve found that more than once I’ve had to admit that some of my carefully reasoned ideas were total nonsense. Today I think I’m doing much better than I have in the past. Now I’m convinced that only half of what I say is totally wrong and the other half is just ordinary drivel. This is a significant improvement as not long ago half of what I said was totally wrong and the other half was pure drivel.
Lex