As a Type 1 diabetic I've had to directly deal with learning how to visibly control my blood sugars so that I can get some control over the disease. Nothing worked until I started to learn about how insulin works and how carbohydrates affects it. The thing that most people don't understand is that diabetes is a reflection of the problems of the way we eat in our society. Diabetes and obesity (which are related through insulin) hardly existed in any society before the advent of modern food processing methods, and a little earlier, the development of grain-based agriculture. All paleoanthropological evidence shows that modern diseases such as diabetes, arthritis, cancer, obesity, coeliac disease and so forth, were extremely rare in paleolithic times. This strongly suggests... and more and more research is showing it so... that there is something wrong with the way we eat today. The current obesity problem in the States is unprecedented in history. Due to the foods we eat, it simply isn't possible that fat (the popularly maligned nutrient) is the culprit, since with each meal only a certain amount of fat can be eaten before one becomes satiated. What has increased exponentially are carbohydrates. Until you actually take heed, in the same way that you weigh each item in a UL gear list, of the amount of carbohydrates that you consume each day in each bit of food you eat, most people have no idea just how much of it there is. Go into any store and look for anything that doesn't have any carbohydrates... today almost nothing is free of them. For health the minimum amount of carbohydrates that you need is about 30 to 40 g of carbohydrates a day, the upper limit is about 150 g, after which the higher you go the more you automatically start gaining weight. In nature most carbs come from the vegetables you eat, which are a vital part of one's diet. Grains, however, have never been a part of the human anatomical development. Even cows can't digest grains!
As a diabetic I check my blood sugar four times a day. I've been doing it for 15 years. Unlike most people I have visual and measured confirmation of how the food I eat affects my blood sugar. Without going into the intricacies of how insulin works with carbohydrates, suffice it to say that no matter how much fat I eat (without accompanying carbs) my blood sugars don't go up. If I eat just a tiny amount of carbs, though, especially things like white sugar and white bread, my blood sugar shoots up. For most of the last 15 years I religiously followed the conventional guidelines of eating low-fat, high-carb diet, mostly vegetarian, and not only did I become diabetic, but I gained weight and had little control of my blood sugars, which is the heart of what causes diabetes. Last June, after reading "The Diabetic Solution" by Dr. Richard Bernstein, and "Primal Blueprint" by Mark Sisson, I tried lowering my carbs for the first time in my life, and upping the fats. To my utter surprise, my blood sugars completely normalized and all my diabetic symptoms went away. including neuropathy of the extremities, a three-year-long fungal infection of my right hand, and even the tinitus in my ears. My HbA1C (long-term blood sugar measurement which is more accurate than home measurements) lowered for the first time in 15 years. My doctor was incredulous. My energy levels went way up, colds disappeared, and I felt better than I had in over 25 years.
Recently I started reading Philip Maffetone's "The Big Book of Endurance Training". Whereas "The Primal Blueprint" goes into great detail about the effects of nutrition, and especially does the best job of explaining insulin and how it works and causes problems, Maffetone's book concentrates on the physical training aspect of "aerobic" and "anaerobic" training. Maffetone explains that aerobic exercise is primarily fat-burning based, whereas anaerobic exercise is glucose-based. Endurance athletes (and this includes mountain walkers) need the slow burn of the fat-burning metabolism, while athletes such as weight lifters and sprinters need the quick energy of sugar-based metabolism. Through decades and thousands of meticulously tested and recorded training of world-class elite athletes, Maffetone came to the conclusion that the healthiest people maintained the best health by focusing on an aerobic threshold, including those people who needed anaerobic development to do their activities. He emphasized that the moment the aerobic base is compromised, all the rest gets compromised as well.
What surprised me was that I had always been taught that aerobic exercise had something to do with the amount of oxygen in the blood and that the more you did, and the harder your trained, the better. Maffetone, however, explains that pushing yourself beyond the threshold of your aerobic base, which falls within the energy output of a fat-based metabolism, is the primary cause of injury, disease, and poor performance. He advocates a low carbohydrate, high fat, moderate protein diet, plus a low level of exercise that never pushes beyond the capability of the aerobic system's threshold. For that a person needs at least three months of slow, easy training (using a a heart rate monitor and maintaining the heart rate within specific levels) so as to train the body to using primarily fat for energy... the ketogenic diet. Most people, because they eat diets high in carbs and push themselves beyond the aerobic level, tend to need more and more carbs in order to maintain their energy levels, with the resulting problems with weight gain, bad blood sugar control and over-production of insulin (which leads to obesity and eventually diabetes), and overtraining. Most people have glucose-based metabolisms. That is why it took Piper 6 weeks to change over to a fat-burning metabolism.
If Maffetone's elite endurance athletes (including many of the world's best ultramarathoners and triathletes) can perform so exceptionally well on a this system without injuries or stress, while often coming from careers ruined by overtraining and carb-bsed diets, then there must be something to the low-carb, high-fat, moderate protein and lots of vegetables recommendations coming out now in paleo circles. Logically it doesn't make sense that there isn't an ideal diet for humans, whereas we seem to have no trouble at all coming up with ideal diets for our pets. We're animals, too, and also have specific needs in nutrition.
That being said, humans are omnivores and adaptable, including with our food. Other books you might want to check out are, "The Omnivore's Dilemma: A Natural History of Four Meals" by Michael Pollan, "Good Calories, Bad Calories" by Gary Taubes, "Deep Nutrition: Why Your Genes Need Traditional Food" by Catherine Shanahan, and "Slow Burn: Burn Fat Faster By Exercising Slower" by Stu Mittleman.
I think people should try out the diet and learn more about how nutrition works before pooh-poohing what it can do. I was very skeptical before I started, especially since, with diabetes, I can't afford to play around with my metabolism. Among diabetics low carb is becoming the de-facto way of maintaining blood sugar control... and a healthy diabetic lifestyle is a healthy lifestyle for anyone.
Piper, I think you really have something there about maintaining heat at night. It could even be said that perhaps many women are colder in the mountains because they tend to eat far less fat than men, and therefore end up with colder metabolisms. It's worth looking more into.