The Atkins Diet Could Make You Hate Life

In the duel between the two most popular diets, it’s a draw: People who eat a lot of carbohydrates and little fat or those who follow an Atkins-style regime of few carbs and high fat will lose roughly the same amount of weight, according to the latest research. But if you care about your feelings as well as your flab, a new study on mood published this week [2] in the Archives of Internal Medicine found a convincing distinction between the two approaches.

Dieters who ate low-carb, high-fat foods for a year were crankier than their peers who followed the more conventional diet. Of course, few people on a diet—no matter the type—are cheery. They have to adhere to strict plans, deal with hunger, swear off foods they like, and, especially if they’re on an Atkins-style program, contend with fatigue, bad breath, and constipation. But the study’s authors speculate that other reasons—perhaps social or chemical—are behind the low-carb mood shift. This new information and future long-term studies could provide clues about why some diets succeed while others fail.

Researchers from Australia’s national science agency [3] randomly placed about 100 dieters into two groups and instructed them to eat roughly the same amount of calories (between 1,400 and 1,700) per day. The low-carb group ate a diet comprised of 4 percent carbs, 61 percent fat, and 35 percent protein, compared with the high-carb group, who consumed 46 percent carbs, 30 percent fat, and 24 percent protein. The majority of participants, who lost about 30 pounds each in the year, experienced a mood lift at the beginning of the trial, presumably because they were pleased with their progress. But by the eighth week, the low-carb group had lost their happiness boost and reported feeling angry, depressed, and confused. The high-carb group, however, still felt good.

At first glance, it might seem as if the Atkins diet is more indulgent. By giving up carbs, you’re mostly left with protein and fat. As long as you avoid grains, potatoes, beans, sugar, milk, and fruit, you can eat unlimited amounts of triple-cream Brie and marbled rib-eye. Even though some experts recommend a lower-fat version with more allowances for carbs, they credit the Atkins diet’s high level of protein, which takes longer to digest than carbs, for making programs easier to follow. One study in The Journal of Nutrition [4] found that dieters who ate more protein reported less hunger and a “greater degree of diet satisfaction.”

But that’s in the short-term. The authors of the Archives of Internal Medicine study suggest that over the long run, dieters who eat less than 60 grams of carbs per day experience either social stigma from rejecting the bread basket one too many times or a change in brain chemistry that kills the buzz. The social explanation seems thin, since people in both camps likely had to endure a year’s worth of questions asking why they couldn’t share a slice of high-calorie birthday cake.

The more compelling hypothesis involves serotonin, a neurotransmitter that regulates mood and sleep. Research from the 1970s by MIT neuropharmacologist Richard Wurtman found that eating carbohydrates creates serotonin. Low-carb dieters therefore have less of the chemical and suffer from anxiety, reduced ability to cope, inappropriate anger, and a “chronic low-level depression,” insists his wife, Judith Wurtman, author of The Serotonin Power Diet [5] and a biologist who ran weight loss programs at the Harvard-affiliated McLean Hospital. Women are especially vulnerable to serotonin fluctuations, since they have only three-fourths of the amount in their brains that men do and are more prone to depression anyway, she says, explaining that serotonin also controls appetite. Her claim: Eating more carbs boosts people’s moods and helps them eat less and lose weight.

The trick, she says, is to eat carbs alone without protein two to three times a day, especially in the late afternoon when many people crave cupcakes and Doritos. In a departure from the seemingly ubiquitous advice to eat mostly complex or low-glycemic carbs, such as quinoa and sweet potatoes, she advocates consuming more simple carbs—which she calls an “edible tranquilizer” —such as a handful of pretzels or sweetened cereal. The result: Your serotonin elevates. Your mood brightens and your appetite lowers, so you won’t overeat at dinner.

But how does one reconcile this advice with warnings that mainlining carbs—especially white sugar and flour—spikes your insulin, wrecks your blood sugar, and causes an energy crash shortly thereafter? How you ought to eat your food is still up for debate, but among researchers, there seems to be an emerging consensus of the best balance—as in a shift away from an extreme low-carb program to a “low-ish carb” one that includes a protein level on the high end of the government’s recommended daily allowance of 10 to 30 percent of calories. A pragmatic approach, says Wayne Campbell, professor of food and nutrition at Purdue University, who also discovered the feel-good benefits of protein in his own studies, would be to eat 30 percent of one’s daily calories as protein, 45 percent as carbs, and 25 percent as fat.

That may not be as decadent as downing In-N-Out cheeseburgers with iceberg lettuce cups [6] instead of buns, but it ultimately might be more manageable and mood-friendly —and should be the studied more over time, too. Although running diet studies over a period of time can be challenging since subjects don’t always report what they eat at home, as Slate’s William Saletan notes [7], we now have more need for good long-term research. Showing how people fare emotionally on a diet seems key to helping them stay on one.