TheFountain: But a lot of starchy, grainy foods consist of empty calories. Why is that optimal?
There's a limit to how many high micronutrient/low-caloric density foods like vegetables or mushrooms I can enjoy, or afford. That 20 oz of spinach in my first example is 19 cups, and only 130 calories. I don't like chewing that much. As it's readily possible to satisfy nearly all the vitamin, mineral, essential amino acid and fatty acid requirements with an intake of only 6-700 calories, I see filling the remaining daily balance of 1000-1200 calories as less a problem of identifying the most nutrient dense foods, than of finding the least harmful ones.
Look long enough, and negative effects can be found for most macronutrient classes. IMO certainly trans-fats, longer chain saturated fats, refined sugars and high glycemic index carbs. MUFAs and omega-6 PUFAs are perhaps better, but dietary MUFAs still cause atherosclerosis in animal models, and n-6 PUFAs are likely proinflammatory when exceeding n-3s. Experimental gerontology and human prospective studies suggest excess protein also bears dangers, at least before retirement age, via excess IGF-1/mTOR signalling and/or excess methionine's oxidative stress/inflammatory effects. What's left? I've yet to discover any negative effects from short chain fatty acids, most fermented from fiber and resistant starch in the colon. n-3 PUFAs, especially EPA/DHA, seem pretty blameless in supplement doses, but in calorically significant amounts may make membranes prone to oxidation. And that leaves relatively lower glycemic index starches (beans up to my protein limit, whole-grains and whole-grain pasta). Are they micronutrient dense? No. Their virtue is that they're low in food components I'm moderating. Beans, tubers, and grains are traditional mainstays in most of the world, so there's no shortage of recipes out there. I tweak the recipes (eg substituting black or wild rice for white) to increase phytochemical content, but I've already got the generally recognized micronutrients well covered.
Potatoes (in my last post) are admittedly not the best exemplar. While they excel in potassium and are surprisingly complete (just short on B12, A, and E), they also have among the highest glycemic indices, and I'm trying to moderated insulin releases in the context of a low-fat/low-protein diet. I'm not pre-diabetic, its just that insulin and IGF-1 signalling are closely intermingled. I'm presently fascinated with the resistant starch story, and it appears that after roasting (but not boiling) and cooling, about half of the starch in a potato undergoes retrogradation to resistant starch, the highest fraction among cooked foods. Another consideration is that if one is restricting/moderating protein as a longevity experiment, satiety becomes more difficult. Hypothalamic mTOR activation, especially by leucine, appears to mediate the increased satiety and weight-loss advantages of high-protein diets. Those attempting some degree of CR and protein moderation must find alternate means of filling full, and I think enlisting the gastric stretch sensors is useful here. Tubers and whole grains have the virtue of relatively low caloric density (300-500 kcal/lb), nowhere as low as vegetables and fruit (100-250 kcal), but well below something like baked goods (1100-1700), and that helps, as does focusing on stew-like dishes (when my meal isn't a salad bowl sized salad).
Edited by Darryl, 03 June 2014 - 10:50 AM.