Walnuts in a healthy low-carb diet

Last updated on April 19th, 2017

Walnuts are a good low-carb food. Like peanuts and almonds, walnuts provide protein, fat and fiber with relatively few net-carbs per serving. For instance, a quarter cup of walnuts has two grams of net-carbs (four grams of total carbohydrates minus two grams of fiber).

Taste and Cost

Some people find walnuts bitter. I admit I prefer the taste of roasted almonds and peanuts, and seldom eat walnuts as a stand-alone snack. The big drawback to walnuts is cost. Many consumers only encounter walnuts in one-cup bags in the supermarket’s baking aisle, and that isn’t a good way to buy them if you plan to eat two or three helpings a week.  For the last year or so, I’ve been buying walnuts in a three-pound bag (about 12 cups) at Costco.  (I have no affiliation with Costco other than shopping there once a month.)  Big bags at a warehouse store are definitely the way to go if you develop a regular walnut habit!

Usually, the way I eat walnuts is in breakfast concoction that I fix two or three times a week. The three-pound bag of walnuts lasts me a couple months or so.

Health Benefits

I was pretty sure walnuts were a healthy food. Now a new study published in the Journal of Nutrition seems to underscore the health benefits. The title asserts the main finding: “Walnut Consumption is Associated with Lower Risk of Type 2 Diabetes in Women.”

Notice, I said “seems to underscore the health benefits.” There are some problems.  The first problem is scope.  As the title indicates, the study was of women and its findings are only directly applicable to women. Indeed, the population studied primarily consisted of white female nurses, and, as the researchers admit,  it is an open question how well the findings can be generalized to other groups.

However, an even bigger problem with the findings is suggested by the careful wording of the title. It merely claims an association between eating walnuts and a lower risk of diabetes. In other words, the women who frequently ate walnuts tended to have or develop type 2 diabetes less often than women who seldom or never ate walnuts. The researchers are careful to point out the correlation does not prove causation.

Unfortunately, the popular press misses such careful distinctions much of the time. I first encountered this walnut research in a story with the title, “Eating walnuts twice a week could slash the risk of type 2 diabetes by a quarter.”  While the weasel word “could” blurs the claim, it still sounds as if a twice weekly dose of walnuts added to any diet and lifestyle would do the trick. In fact, the most we can say is that the typical diet and lifestyle of a white woman who eats walnuts twice a week is associated with a lower risk of diabetes.

It could be that walnuts are replacing more harmful foods.

But while my skeptical self doubts claims of causation (which, again, can’t be pinned on the original researchers), I remained convinced that walnuts — and many other kinds of nuts — are a great component of a healthy low-carb diet.