Dietary Guidelines Committee Appears to Ignore Vast Majority of Low-carb Studies

By Ted Eytan, MD, MS, MPH

We know this post comes at a sensitive time, please see a link to our statement about the coronavirus pandemic at the bottom of this post.  

As you may know, the process for the 2020 Dietary Guidelines for Americans (DGA) for the first time included a formal review of low-carbohydrate (“low-carb”) diets. However, as the guidelines process has unfolded, with the last meeting of the Dietary Guidelines Advisory Committee (DGAC) concluded in March, there is serious reason to doubt that low-carbohydrate diets will be properly reviewed—or even reviewed at all.   

The Low-carb Action Network (L-CAN) has been concerned about the DGAC’s approach to low-carb studies from the start, when the committee announced its protocols for reviewing the science. These protocols inaccurately define the low-carb diet as one with less than 45% of calories from carbohydrates. The science clearly shows that a true low-carbohydrate diet has less than 25% of its calories coming from carbohydrates. Using an incorrect definition, as the DGAC has done, will water down and obscure the significant health benefits that are found on a “true” low-carb diet, thus providing inaccurate and unreliable information to the public on this dietary approach.  

The same March meeting revealed several ways in which the committee is misunderstanding or excluding scientific evidence on low-carb diets.

Most notably:

1. The DGAC had not finished its reviews of low-carb diets and therefore did not announce any conclusions. In the meeting, the same statement was made three times: “the full body of evidence is still under review.” (timestamps: 45:24, on obesity, 38:03 on cardiovascular disease, 51:12 on diabetes). This means the review will be conducted outside the public view, and there will be no opportunity for public comment on the conclusions prior to publication of the draft scientific report.
2. The committee excluded studies on weight loss. This exclusion means that a wide swath of relevant literature was removed from consideration. We know that much of the reason for studying low-carbohydrate diets has been due to its weight-loss potential.
3. The committee excluded all studies below 25.3% of energy as carbs. Committee member Dr. Carol Boushey stated, “No studies meeting inclusion criteria examined carbohydrate distribution below 25.3 percent.”  (timestamp 0:34:00) The L-CAN database has 52 such studies. Due to the committee’s inappropriately restrictive exclusion criteria, the DGAC review of low-carb studies will therefore be based on only a small fraction of the available literature. Read our blog  post on this here.
4. The committee suggested that the Dietary Guidelines might not even address low-carbohydrate diets at all. In an exchange between committee members, toward the end of the full committee meeting on March 13 (afternoon session 0:50:59), Dr. Steven Heymsfield remarked, “Things like high- versus low-carbohydrate diets, keto diets, time-restricted feeding, these are all issues that we didn’t deal with, at least in the committee I was on, two committees I was on, and I just wonder, I know you don’t want to take up a lot of space in that document, but I think… these are topics that are hard to ignore, and I think a lot of people in the public are interested in them.” In response, DGAC chair Dr. Barbara Schneeman said: “we need to acknowledge those comments and acknowledge our discussion, while we haven’t been the body to look at the evidence, ….there are other federal agencies that could be… If it’s not the Dietary Guidelines, where else can it be dealt with?” 

Is it possible that the DGA will ignore low-carb diets altogether? 

Time to Take Action 

Given the exclusion of relevant research, and a possible move not to review low-carb studies at all, we think it’s time to have our voices heard.  Otherwise, we will have another set of Guidelines, lasting until 2025, without a range of options for health, including a true low-carb diet. This would be a bad outcome for Americans with obesity, pre-diabetes, diabetes, heart disease and more, who could benefit from this option.  

L-CAN members and friends can contact their members of Congress to ask the DGAC to do its work properly, per its Congressional mandate to review the “best and most current science”. 

If this is not possible under the current time constraints, then perhaps it’s time to re-evaluate the entire process so that comprehensive scientific reviews can be completed. 

• Click here to send a comment to the Dietary Guidelines for Americans Committee by March 27 

• Click here to send a message to your members of Congress 

Note: L-CAN’S position is that a low-carbohydrate diet can be comprised of either animal- or plant- sourced foods or both. L-CAN has collected the success stories of people benefiting from low-carbohydrate diets who follow a vegan lifestyle, a carnivore lifestyle, or one that is somewhere in-between. From a policy perspective, we do not support one food source over another in the implementation of a low-carbohydrate diet. 

In solidarity: please see our statement on the coronavirus epidemic.