Low-carb diets are far and away the most effective at alleviating all symptoms of metabolic syndrome -- high body fat, high triglycerides, insulin resistance, etc. -- because these all spring from throwing your blood sugar levels outta whack, and that is caused by eating too many carbs. Plus they are the least physiologically painful diets to go on because fat and protein satisfy hunger, while carbs cause hunger by driving up insulin and thus locking away fat and depriving you of energy -- so your body screams at you to eat some more. You don't have to count calories in general, you get to eat tasty food, you lose your sweet tooth, and you're more energetic overall.
So why do people who experiment with low-carb eating and see the positive results for themselves give up? My mother jumped on the low-carb bandwagon around 2003 or so and truly seemed like a different person. Approaching 50 years old, she'd lost most of the body fat she'd built up during her 40s and had so much energy she didn't know what to do with it. Exercise was something she wanted to do, not a chore, and even after getting back from the gym she would still have enough energy to jump and bounce around the living room, just to show off how healthy she was. But the low-carb fad died and like most Americans she's now back to eating mostly carbs, although they tend to be low-glycemic. She still competes in ballroom dancing, but her energy level isn't what it used to be. Last summer I got my father on a low-carb diet for a few weeks or months, and he lost weight, wasn't hungry, and never felt cranky. By the end of the summer, though, he'd gone back to his old ways.
These examples are hardly atypical. It's understandable why other dieters would revert, but it's puzzling with low-carb eaters because everything starts to improve and they can see it with their own eyes. It is not a diet that requires a constant exercise of willpower because, again, the food tastes great, you don't have to count calories, and your health picks up. And since you lose your sweet tooth, it's not the eventual caving in to that pint of ice cream. I indulge in sweets once every two or three months, but then I go right back because it only takes one pint of ice cream for me to say "that's enough." After that, sweets are too saccharine to tolerate, and I want to get back to eggs, chorizo, and pate.
Gary Taubes, author of Good Calories, Bad Calories, has speculated that those who go back to a high-carb diet do so because they lack support from their doctors and other health care people -- indeed, they might get an earful about how this diet is going to kill them right away. That hectoring from the man in the white coat is enough to make the low-carb eater second-guess what's best for themselves. This means that the only people who will take to low-carb eating over the long term are those who are fine with -- and may even take pleasure in -- telling Dr. Know-It-All how far they're veering from his supposed dietary wisdom. Remember this little rant by Denis Leary in Demolition Man?
I think Taubes is right about that, but it actually applies much more broadly to everyone who will ever find out what you eat -- not only those in your social circle but anyone they might tell, other patrons when you're eating out, and so on. They all believe, wrongly, that eggs, sausage, butter, etc., is poison and that grains are healthy. They've internalized this from what the experts in the private sector say and from governmental warnings and propaganda. Most of the time the experts are right, but not here. If nutrition had no government interference, the diets proven to do best would win acclaim.
Once the government steps in, though, it has no incentive to find out what a good diet is -- it's not going to go bankrupt if it makes the wrong recommendations, unlike a private dieting firm. People trust the government when it comes to issuing warnings on safety -- is it safe to fly, to drive without seatbelts, etc.? -- so once the government scares the hell out of everyone about eating animal products, people will take that very seriously and not be likely to change their minds about it. *
So a low-carb eater is going to have to endure the disgusted looks and shaming stares from not only their social circle whose thoughts they care about, but also from the mob of mankind. "Jesus -- beef with butter, then ham and eggs with cheese. I guess he just doesn't care about his health. What a filthy pig." Even below that are the friendly jokes they'll always hear relating to their diet. It's not a brazen insult, but still a stream of remarks about your diet raises the psychic cost of eating that way. "There goes agnostic ordering a burger without a bun," or "So, what, you're too good to eat breadsticks? Are you saying we're bad people for eating them, then?"
And notice how no one -- anymore -- will make jokes about someone's vegetarian or vegan diet. Now they make remarks if you're an anti-vegan! How perverted has the received wisdom become?
I think it's this regard for peer approval, which in general is a good thing that keeps us from going off the deep end, together with our peers' wrongheaded beliefs about what healthy food is, that makes it so tough for most people to stay on a low-carb diet. These barriers make sure that the only ones who will enjoy the diet long-term are those who aren't moved by peer disapproval if they believe themselves to be in the right. Hey guys, I know you all think this is bad eating, but with all due respect you don't know anything about nutrition, so I'm going to politely ignore your attempts at shaming me into the skin-destroying and energy-sapping diets that you all follow because the experts and the government told you to. If you've spent any time reading low-carb people, you can tell that they have this contrarian and slightly libertarian streak.
This explains why it was easy to follow a low-carb plan in the early-mid 2000s. It suddenly became fashionable and therefore pre-approved by a large fraction of the crowd. You wouldn't have felt like a weirdo, unlike now. The views of doctors, health experts, government screwballs, etc., did not change at all during that time or since. What changed was what the crowd believed. So while Taubes was pretty close, it's actually how the mob is going to judge us that determines how easy or tough it will be to do something. We care less about our own health than we do about how others perceive our health-related behaviors.
* This shows why low-carb diets do not win out even among private dieting firms. The average person does not trust a for-profit firm to figure out what healthy is because he distrusts the profit motive. Since the government has no such motive, he will trust them to figure out what's safe. Suppose that seatbelts didn't really reduce mortality risk, but that the government kept a steady stream of warnings about the dangers of driving around unbuckled, in contrast to private firms who said "don't listen to that bull." Consumers would trust the government's warnings and demand seatbelts from for-profit carmakers -- even if the latter were not required by law to have them.
Similarly, when the government warns that dietary fat and cholesterol are harmful, it doesn't matter if it's nonsense. People will believe the government because there's no profit motive for them to lie, and they'll therefore demand diet programs from private firms that are all in the low-fat / low-cholesterol direction. They just wouldn't trust one that said "eat more beef and liver, and less bread and sugar." And once more, people really care about how others view them rather than about their own health, so the private firms that will dominate in the dieting industry are those that are best at giving consumers a diet that will garner the highest approval ratings from the crowd, not those that are best at improving the consumer's blood lipid profile or other objective measures of health.