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Topical Area: Dietary Patterns

Dietary Patterns (Poster Session)

(P14-010-23) Defining “Low-Carb” in the Scientific Literature: A Scoping Review of Clinical Studies

Sunday, July 23, 2023
11:45 AM – 12:45 PM ET
Location: Poster Board 10

    Presenting Author(s)

  • Violeta Chacón, PhD (she/her/hers)

    Alumna
    Freidman School of Nutrition Science and Policy at Tufts University
    Boston, Massachusetts, United States

    • Co-Author(s)

  • KC

    Kelly C. Cara, M.S. (she/her/hers)

    PhD Candidate
    Tufts University, Friedman School
    Fredericksburg, Texas, United States

  • MC

    Mei Chung, PhD

    Associate Professor of Public Health and Community Medicine
    Friedman School of Nutrition Science and Policy at Tufts University
    Boston, Massachusetts, United States

  • Taylor C. Wallace, PhD, CFS, FACN

    Principal & CEO / Adjunct Professor
    Think Healthy Group, LLC
    Washington, District of Columbia, United States

Disclosure(s):
Violeta Chacón, PhD: No relevant financial relationship(s) with ineligible companies to disclose.
Kelly C. Cara, M.S.: No relevant financial relationship(s) with ineligible companies to disclose.


Objectives: To conduct a comprehensive scoping review of clinical studies to better understand how researchers define low-carbohydrate (LC) diets.

Methods: This study follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement scoping review extension. Literature was searched from Jan. 1 to June 10, 2022 in three bibliographic databases. Published articles, in English, that included LC diets in human adults were considered, where the unit of analysis was one article. Studies on macronutrient contents that did not specify carbohydrate content were excluded. Qualitative evidence is presented in summary tables, by type of LC definition and primary outcome.

Results: The review included 508 articles (317 randomized controlled trials, 99 crossover, 33 before-and-after, 12 non-randomized, and 47 other trials). Most articles examined the effects of LC diets in healthy adults (62.4%), 40 to 59 years old (55.5%), with obesity or overweight (66.1%). The most reported primary outcomes were weight or body composition (29.9%), diabetes (18.7%), or cardiovascular risk factors or outcomes (12.9%). More than half definitions (56.9%) used percent of energy from carbohydrates and of those, 48.7% defined them as 20% of energy from carbohydrates or below. About one fourth (22.9%) used only grams per day and most of these used 20 or 50 grams per day (primarily Ketogenic and “low-carbohydrate”). The rest (24.8%) used a maximum grams per day or grams per body weight. One fourth (25.1%) used standard or commercial dietary patterns (e.g., Mediterranean-LC, DASH-LC). The most common types of diets reported in articles with weight or body composition as primary outcomes were Ketogenic and low-carbohydrate diets. Those that reported diabetes or cardiovascular risk factors or outcomes used “carbohydrate reduced/restricted/controlled/moderate” or “low-carbohydrate” diets (78.3% and 66.7%, respectively).

Conclusions: We found a large number of trials using LC diets for weight or body composition, diabetes, and cardiovascular outcomes. There is a wide variety of quantitative definitions and terms used for LC diets. Systematic reviews are needed to assess actual intake, outcomes, adherence, and safety of LC diets.

Funding Sources: Unrestricted investigator-initiated grant from Simply Good Foods USA, Inc. to Think Healthy Group, LLC.