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Confirmatory factor analyses of the ORTO 15-, 11- and 9-item scales and recommendations for suggested cut-off scores

A Correction to this article was published on 01 June 2019

This article has been updated



To explore the validity and recommend cut-off scores in an English-speaking sample for 9, 11, and 15-item versions of the ORTO measure for orthorexia, a proposed eating disorder characterised by a pathological obsession with consuming only ‘healthy’ foods.

Materials and methods

The sample comprised of 585 participants (82.4% female) who completed an online questionnaire containing the ORTO-15, Eating Attitudes test, Obsessive Compulsive Inventory Revised. A series of Confirmatory Factor Analyses were conducted to test model fit. Binary logistic linear regression and receiver-operating-characteristics (ROC) analyses were used to obtain cut-offs.

Results and conclusion

Results showed that none of the three published versions (9, 11, and 15-item) of the ORTO produced an acceptable model. Subsequent exploratory and confirmatory factor analyses yielded a seven-item version of the ORTO (ORTO-7) with a strong and stable factor structure. Analysis of cut-offs revealed that a cut-off score of equal or greater than 19 on the ORTO-7 represents probable orthorexia.

Level of evidence

Level V, descriptive study.

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Fig. 1

Change history

  • 01 June 2019

    Due to an unfortunate error, interpretation of the ORTO-7 cut-off score is incorrect.


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Author information




All authors identified on this manuscript have contributed equally to the study and provide approval for the final version of this manuscript.

Corresponding author

Correspondence to Simon R. Knowles.

Ethics declarations

Conflict of interest

The authors declare that this research was conducted in the absence of any conflict of interest.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Informed consent

Informed consent was obtained from all individual participants included in the study.

Additional information

This article is part of  the topical collection on Orthorexia Nervosa.

Appendix: ORTO-7

Appendix: ORTO-7

Please indicate the degree to which the following items apply to you.

Scoring key:

1 = Always

2 = Often

3 = Sometimes

4 = Never

1. When eating, do you pay attention to the calories of the food? –––
2. In the last 3 months, did the thought of food worry you? –––
3. Are your eating choices conditioned by your worry about your health status? –––
4. Does the thought about food worry you for more than 3 h a day? –––
5. Do you think your mood affects your eating behaviour? –––
6. Do you think that the conviction to eat only healthy foods changes your lifestyle (frequency of eating out, friends, etc?) –––
7. Do you feel guilty when transgressing? –––

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Moller, S., Apputhurai, P. & Knowles, S.R. Confirmatory factor analyses of the ORTO 15-, 11- and 9-item scales and recommendations for suggested cut-off scores. Eat Weight Disord 24, 21–28 (2019).

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  • Orthorexia
  • Scale validation
  • Confirmatory factor analysis
  • Disordered eating