Citation: Phelan, J.M.; Joyce, J.M.; Bode, K.; Rosenkranz, S.K. Opportunities for Maximizing the Dietary Quality of Fad Diets. Nutrients 2023, 15, 4526. https://doi.org/10.3390/ nu15214526 Academic Editor: Alaa El-Din A. Bekhit Received: 3 October 2023 Revised: 18 October 2023 Accepted: 21 October 2023 Published: 25 October 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). nutrients Article Opportunities for Maximizing the Dietary Quality of Fad Diets Jessica M. Phelan 1,2, * , Jillian M. Joyce 3 , Katherine Bode 3 and Sara K. Rosenkranz 4 1 Department of Food Nutrition Dietetics and Health, Kansas State University, Manhattan, KS 66506, USA 2 Department of Health and Human Performance, Fort Hays State University, Hays, KS 67550, USA 3 Department of Nutritional Sciences, Oklahoma State University, Stillwater, OK 74078, USA; jill.joyce@okstate.edu (J.M.J.) 4 Department of Kinesiology and Nutrition Sciences, University of Nevada, Las Vegas, NV 89154, USA; sara.rosenkranz@unlv.edu * Correspondence: jmphelan2@fhsu.edu Abstract: The quality of American diets, measured by the Healthy Eating Index (HEI), has remained stable and low since 2005. The Dietary Guidelines for Americans 2020–2025 call for research analyzing dietary patterns to determine how guidelines might be altered to increase healthy eating. The present paper seeks to determine the dietary quality of popular fad dietary patterns among Americans. A definition of “fad diet” was created, and Google Trends© was searched for popular diets to determine popular dietary patterns based on the fad diet definition. Finally, eight dietary patterns were identified for inclusion. One-week sample menus were created for each dietary pattern, maximizing alignment with the DGAs but staying within the dietary pattern parameters, and then scored according to the HEI 2015 to determine the dietary quality. Total HEI scores ranged from 26.7 (Carnivore) to 89.1 (Low-FODMAP); the six highest total HEI scores were in the range of 77.1–89.1 out of 100 points. This analytical approach showed that some of the included popular fad dietary patterns have the potential to attain a high dietary quality. Rather than suggesting one “best” diet or dietary pattern, there is opportunity to maximize dietary quality in the context of dietary patterns that are considered fad diets. Keywords: dietary quality; college student; fad diet; healthy eating index; dietary analysis 1. Introduction The 2020–2025 version of the Dietary Guidelines for Americans (DGA) [1] revealed that, despite continual public health nutrition education, policy, and programmatic efforts, Americans are not adhering to the dietary guidelines [2]. Measured yearly in the period of 2005–2016, scores were in the range of 56–60 out of 100 on the Healthy Eating Index (HEI), which measures dietary quality or healthfulness of dietary patterns based on adherence to the DGAs [3]. These scores suggest that a relatively poor adherence has persisted over a long period of time [4]. Additionally, around 17% of adults in 2015–2018 reported following some sort of special diet [5]. To determine why Americans have maintained low HEI scores over the past several DGA releases, the Dietary Guidelines Advisory Committee (DGAC) suggests that researchers take into consideration existing dietary patterns that influence dietary consumption to better manage and treat diet-related diseases. For the purpose of this study, we focus on the less scientifically accepted dietary patterns that Americans might be consuming, sometimes referred to as “fad diets”, rather than the dietary patterns that are scientifically well-established, and generally regarded as health-promoting, such as the Mediterranean diet or Dietary Approaches to Stop Hypertension diet. Little research has been conducted to determine the potential for high dietary quality among fad dietary patterns. Research suggests that the Westernized diet, followed by many Americans, is charac- terized as high in calories, saturated and trans fats, sugar and sodium, with large portions, and low in fruits, vegetables, and fibers [6]. Furthermore, around 80% of Americans ha- bitually under consume fruits, vegetables, and dairy/dairy alternatives as compared to Nutrients 2023, 15, 4526. https://doi.org/10.3390/nu15214526 https://www.mdpi.com/journal/nutrients