Chow Line: Carbohydrates: How low is low?

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I heard about a study recently that said low-carb diets worked better than low-fat diets. My question is, how “low” is low-carb?

You’re likely talking about a study published in early September in the Annals of Internal Medicine called “Effects of Low-Carbohydrate and Low-Fat Diets: A Randomized Trial.”

The authors’ conclusion — that a low-carbohydrate diet was more effective for weight loss and heart health — got a lot of press. But other experts raised their eyebrows after reading the whole study.

For the study, researchers followed 119 participants for a year and found those placed on a low-carbohydrate diet lost an average of 12 pounds, compared with an average of just 4 pounds for those on a low-fat diet.

For this study, “low-carb” meant less than 40 grams of carbohydrates daily. If you’ve ever counted carbs, you know that’s not a heckuva lot. A cup of milk has 13 grams of carbohydrates. A medium apple, 25 grams. And that’s not even counting bread or pasta. You get the point: Critics of low-carb diets suggest that most people find them too restrictive to adhere to for long, and they suspect any weight loss associated with them is essentially due to overall calorie restriction.

This study seems to support those points: Nearly all of the weight loss enjoyed by the low-carb group occurred in the first three months, where the group also reported consuming 190 fewer calories a day than those on the low-fat diet.

Additionally, the low-carb participants reported a higher consumption of carbs than they were actually supposed to eat: about 80 grams daily at first, and up to 112 grams daily by year’s end.

That said, there remains serious discussion about standard dietary advice that suggests a hefty portion of the diet — 45-65 percent of calories — should come from carbohydrates.

Some evidence suggests that moderately restricting carbohydrates to 25 to 45 percent of calories a day (that would be equal to 125-225 grams on a 2,000 calorie per day diet) and at the same time boosting protein and healthy fats could help weight loss by reducing hunger pangs. But most dietitians believe that very low-carbohydrate diets — those that restrict carbs to less than 50 grams a day, or 5-15 percent of calories, aren’t feasible for most of us.

Most dietitians agree that a healthful diet can take many forms, as long as it includes a variety of fruits, vegetables, whole grains, lean protein and healthy fats, and restricts added sugars. The key is to find something you can live with for the long term.

Chow Line is a service of Ohio State University’s College of Food, Agricultural, and Environmental Sciences and its outreach and research arms, Ohio State University Extension and the Ohio Agricultural Research and Development Center. Send questions to Chow Line, c/o Martha Filipic, 2021 Coffey Road, Columbus, OH, 43210-1043, or filipic.3@osu.edu

Editor: This column was reviewed by Bridgette Kidd, Healthy People program specialist for Ohio State University Extension, the outreach arm of the College of Food, Agricultural, and Environmental Sciences.

For a PDF of this column, please click here.

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CFAES News Team
614-292-2270
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Bridgette Kidd
OSU Extension, Healthy People