Participants were recruited from undergraduate courses (in nutrition, exercise science, athletic training, and psychology) at a large university in the southern region of the United States, as well as through an Instagram advertisement with the audience interests set to target healthy eaters (e.g., “healthy eating,” “clean eating,” “paleo”). Of the 471 participants who completed the survey, the majority were women (86%; 13% men, 1% non-binary), were White (48%; 28% Hispanic or Latinx, 9% Black, 5% Asian American, 9% biracial or multiracial), and had some college without a degree at the time (59%; 4% Bachelor’s degree, 6% Associate’s degree, 25% high school diploma, 5% no high school diploma). Their ages ranged from 18 to 46 years (M = 19.98, SD = 3.56), and body mass index (BMI) ranged from 15.45 to 48.25 kg/m2 (M = 24.77, SD = 5.67).
For this study, which was approved by Texas State University’s Institutional Review Board, participants provided informed consent and then completed an online survey through Qualtrics. The survey began with a demographic questionnaire, followed by measures of ON, frequency of substance use, level of dependence or substance abuse, and reasons for using these substances.
ON was assessed with the Orthorexia Nervosa Inventory (ONI)  that is comprised of 24 statements about eating, to which participants use a 4-point Likert rating to indicate how true each statement is for them based on their current eating habits. This inventory produces scores on three different scales. First, the ONI Behaviors scale includes nine items on obsessive behaviors and preoccupation with healthy eating (e.g., “I strictly avoid all foods I feel are unhealthy”). Second, the ONI Impairments scale includes ten items on either psychosocial impairments (e.g., “My healthy eating is a significant source of stress in my relationships”) or physical impairments (e.g., “The stricter I become with my diet, the more I seem to experience one or more physical symptoms such as fatigue, faintness, heart racing, nausea, diarrhea, pain, etc.”) resulting from their oftentimes extreme behaviors. Third, the ONI Emotions scale includes five items on emotional distress resulting from violations of their strict dietary rules (e.g., “I feel much guilt or self-loathing when I stray from my healthy diet”). For all scales, higher scores represent higher levels of ON symptomatology. Regarding internal consistency, with data from the current study, Cronbach’s alpha was .93 for the total ONI, and ranged from .86 to .89 for its three scales.
Frequency of substance use was assessed as both a dichotomous categorical variable (i.e., users vs. non-users) and a continuous variable. For the categorical variables, three yes-or-no questions asked whether the participants smoke cigarettes or vape, whether they drink alcoholic beverages, and whether they have ever consumed or used a non-prescribed illicit/illegal drug. For the continuous variables, seven questions, each with five response options, asked how much they smoke or vape per day (with responses ranging from “0-5 cigarettes or comparable vaping” to “30+ cigarettes or comparable vaping”), how often they have a drink containing alcohol (with responses ranging from “Never” to “4+ times a week”), and how many times they used the following non-prescribed illicit drugs during the past 12 months (with responses ranging from “Not at all” to “More than 20 times”): stimulants such as amphetamines, methamphetamine, or cocaine; depressants such as barbiturates, benzodiazepines, or rohypnol; opiates such as heroine, fentanyl, or vicodin; hallucinogens such as PCP, LSD, or ecstasy; and marijuana/cannabis.
Substance dependence or abuse was assessed with the Cigarette Dependence Scale-5 (CDS-5) , the Alcohol Use Disorders Identification Test (AUDIT) , and the UNCOPE . First, the CDS-5 includes five Likert-response questions that were slightly modified for the current study to include vaping along with cigarette smoking (e.g., “How would you rate your addiction to cigarettes/vaping on a scale of 0-100?”). Second, the AUDIT includes ten Likert-response questions asking about problematic drinking behavior (e.g., “How often during the last year have you found that you were not able to stop drinking once you had started?”). Finally, the UNCOPE includes six yes-or-no questions asking about drug abuse or dependence (e.g., “Have you ever neglected some of your usual responsibilities because of using drugs?”). For all scales, higher scores represent higher levels of substance dependence or abuse. With data from the current study, Cronbach’s alpha was .94 for the CDS-5, .83 for the AUDIT, and .86 for the UNCOPE.
The motivations for using substances were assessed with the Reasons for Smoking Scale (RSS) , the Drinking Motives Questionnaire-Revised (DMQ-R) , and a modified DMQ-R as described below. First, completed only by smokers or vapers (n = 97), the RSS is comprised of 11 statements pertaining to reasons for smoking or vaping, to which participants use a 5-point Likert rating to indicate how true each statement is for them. It includes four scales: RSS Pleasure (e.g., “I find smoking cigarettes or vaping pleasurable”), RSS Stimulation (e.g., “I smoke cigarettes or vape to stimulate me, to perk myself up”), RSS Tension Reduction (e.g., “I light up a cigarette or vape when I feel angry about something”), and RSS Weight Control (e.g., “I rely upon smoking cigarettes or vaping to control my hunger and eating”). Second, completed only by alcohol drinkers (n = 344), the DMQ-R is comprised of 20 reasons typically given for drinking alcohol, to which participants use a 5-point Likert rating to indicate how often they drink for each reason. It includes four scales: DMQ-R Enhancement (e.g., “Because it’s exciting”), DMQ-R Social (e.g., “To be sociable”), DMQ-R Conformity (e.g., “Because your friends pressure you to drink”), and DMQ-R Coping (e.g., “Because it helps you when you feel depressed or nervous”). Last, completed only by illicit drug users (n = 191), the modified DMQ-R was nearly identical to the original DMQ-R, except that “drink/drinking alcohol” was revised to “use/using drugs” throughout the instructions and questionnaire items. With data from the current study, Cronbach’s alpha ranged from .79 to .87 for the RSS scales, .85 to .90 for the DMQ-R scales, and .90 to .92 for the modified DMQ-R scales.
Data were analyzed using the SPSS Statistics 26 software. Independent-measures t tests were conducted to assess group differences between users and non-users on the total ONI score and each of its scales, and Pearson correlation analyses were conducted to assess the ONI relationships with the remaining, continuous variables measuring frequency of use, level of dependence or abuse, and motivations for use. A standard alpha criterion of .05 was used to determine statistical significance. For significant group differences, Cohen’s d was calculated, with a value of .2 considered a small effect, .5 a medium effect, and .8 a large effect. For significant correlations, an r value of .1 was considered a weak relationship, .3 a moderate relationship, and .5 a strong relationship.