In the early 1970s, Dr. Atkins made a splash sharing a similar philosophy. But in the early 1980s, the U.S. Department of Agriculture told Americans that they should eat less fat for better heart health. Low-fat, high-carb products popped up everywhere, and we embraced our pasta bowls.
Then came another about-face. In the last couple of decades, researchers have been telling us that fat isn’t all bad—and that loading up on processed sugary sweets has been hurting our health and waistlines.
Meanwhile, the Atkins diet made a comeback with Dr. Atkins’ New Diet Revolution, and variations on protein-rich eating plans popped up (Zone! South Beach! Paleo!). Fast-forward to today, when books like Wheat Belly and last year’s Grain Brain claim that carbs, especially wheat, can cause everything from dementia to belly fat.
No doubt, you can drop pounds on a low-carb diet in the short run. A 2012 review of studies (most of them lasting 12 months or less) found that obese people on lower-carb diets lost weight and improved their cardiovascular health (lower blood pressure, higher good cholesterol). But when low-carb diets are compared with other plans, the results are less impressive.
A landmark Harvard study published in 2009 in The New England Journal of Medicine randomly assigned overweight people to one of four diets with similar calorie counts but diferent proportions of fats, carbs and proteins to see whether a low-carb diet (getting 35 percent of calories from carbs) had any beneﬁts over diets with higher carb counts.
Surprise: After two years, there was little diference in weight loss among the participants; all the diets led to improvement in cardiovascular risk factors as well. In other words, in the short term you’ll likely lose weight on any diet that cuts calories.
But not all plans are equally good for you. New research suggests that following a carb-restricted diet for more than a few years could actually harm your health. A review published last year in Plos One looked at 17 prospective epidemiological studies (in which subjects ﬁll out food diaries and are followed for years); these are less rigorous than clinical studies but are the only way to understand long-term efects of diet in the real world.
When people eating the lowest-carb diets (typically 30 to 40 percent of calories) were compared with folks on the highest-carb eating plans (generally 60 to 70 percent of calories), it was found that the low-carb dieters had a 30 percent higher risk of death from all causes in the long run.
“What we discovered was if you continue on the low- carb diet for many years, you could die younger,” says lead author Hiroshi Noto, MD, of the National Center for Global Health and Medicine in Tokyo. “That may be because if someone eats a low-carb diet, most likely they resort to more fat or animal protein, which can be bad for your blood vessels.”
What’s more, a study published earlier this year in Cell Metabolism suggests that having a diet high in animal protein in midlife (age 50 to 65) can signiﬁcantly raise your risk of dying of cancer, compared with eating a low-protein diet.