The 'Big Meanies' are dietary evils. They are the foods that I try to avoid. The four main ones are Flour, Beans, Fructose, and PUFAs.
I avoid flour because of Wheat Germ Agglutinin (WGA), gliadin, phytates, and wheat lectins. Phytates (present in all sorts of food plants) reduce the bioavailability of minerals, vitamins, and other nutrients. Gliadin is one of the two major types of Gluten proteins; it is incompletely digested, and its absorption into the lining of the small intestine leads to an immune response, which causes inflammation of the lining and can cause auto-immune disorders through molecular mimicry. This is a basic idea in the problems with many of these foods: they disrupt the digestive system, possibly allowing foreign proteins to get into the blood stream, where the immune system decides to get rid of them, which then causes a cross-reaction to normal tissue somewhere else in the body. Lectins are sugar-binding proteins; many of them (such as ricin) are horribly toxic.
Beans contain a wide range of lectins (see above). They also contain a lot of carbs, although those carbs are not generally digestible. That means the carbs make it to the colon, where various bacteria ferment it, producing gas, bloating, general unpleasantness, and possibly dysfunction. The primary 'advantage' to beans is that they're a source of protein that isn't animal based. Since I have no trouble eating animal foods, I don't need another source. Given the risks, I see no reason to eat them. I avoid all beans.
Unlike glucose, which can be used for energy by every cell in the body, fructose has to be processed by the liver. In this way it's like alchohol, and your liver reacts the same way to a high dose of fructose as it does to a high dose of alcohol: by producing fatty accumulation (steatosis) in the liver. As fat accumulates within liver cells, it can cause those cells to burst and die. The scar tissue that eventually forms is the characteristic sign of cirrhosis.
Morphologically, there is no distinction between alchoholic steatosis and non-alchoholic (eg fructose-induced) steatosis. Drinking fruit juice isn't healthy; you're just over-dosing on fructose, possibly leading to liver dysfunction.
Due to years of eating the Standard American Diet, I'm starting to develop Metabolic Syndrome. I avoid carbs for that reason, and fructose specifically because it's a carb and because it stresses the liver.
I don't think that low doses are fructose are problematic (as with many things, the dose makes the poison). However, since I'm trying to lose weight, I'm avoiding carbs to induce my body to burn off all this stored fat I'm carrying around. So no low doses of fructose!
PUFA = Poly-Unsaturated Fatty Acid. Because unsaturated acids have double-bonds that can be split to adopt nearby radicals (that means that one of the 'missing' hydrogens in the long fat chain gets replaced by oxygen). Fire is oxidation. I'm sure you've heard that 'free radicals' are bad. 'Free radicals' really means free (unbound) oxygen. One of the things that oxygen likes binding to, that makes it bad, is unsaturated fatty acids. Just say no to oxidized fatty acids. (Rancid food is oxidized food; rancid butter is when the unsaturated fat in butter gets oxidized. No animal fat is 100% saturated; in fact, generally not so. Beef fat tends to have the most saturated fat, but it's still not 100%.)
I've read a bunch that suggests that the oxidation of PUFAs leads to arterial damage that leads to plaque build-up that leads to a big plaque chunk dislodging that leads to artery blockage that leads to a heart attack.
IGNORE THE REST -- I'm going to copy and paste this elsewhere
Sugars are basically carbon rings with a few methyls or hydroxyls hanging off here and there. If there's only one ring in a sugar, it's a monosaccharide. Two rings connected to each other make disaccharides. Many make for polysaccharides, also called starches. Humans aren't well adapted to digesting starches; we can digest some, but not others.
Anyway, fructose is one of the major monosaccharides in the human diet, along with glucose and galactose. Sucrose (table sugar) is one molecule of fructose combined with a molecule of glucose. Our bodies will split sucrose into fructose and glucose. Fructose is sweeter than glucose, which is one reason why high-fructose corn syrup is used as a sweetener.
PUFA is Poly-Unsaturated Fatty Acid. A fatty acid is a long-chain carboxylic acid, which means it's got a couple oxygen atoms at one end (the head) then a long chain of carbon atoms. Carbs like to bond in groups of four, so that means each carbon in the chain is bound to the carbon ahead of it, the carbon behind it, then two other atoms -- generally hydrogen. A fatty acid is considered saturated if all of the carbons in this chain are bound to two hydrogens. Sometimes ...