The Reliability and Validity of the PortionSize and MyFitnessPal Apps (Study 1: Laboratory-based Evaluation)
Conditions: Dietary Habits
Sponsor: Pennington Biomedical Research Center



1
Title: The reliability and validity of the PortionSize and MyFitnessPal apps (Study 1: 
Laboratory-based evaluation).
Principal Investigators: Corby K. Martin, Ph.D.; John W. Apolzan, Ph.D.
Co-Investigator: Stephanie T. Broyles, Ph.D, James L. Dorling, Ph.D.
Protocol Version Date: December 1, 2020
Background
Accurately quantifying food intake is vital to promoting health and reducing chronic 
disease risk. Food intake encompasses energy intake, nutrient intake (macronutrients, 
micronutrients, vitamins, minerals), and intake of various food groups (e.g., fruits, 
vegetables), and thus reflects the nutritional status of individuals. Nutrition affects 
disease risk, including risk of developing obesity, 1 diabetes, 2 and cancer, 3 all of which 
negatively affect the United States (U.S). Nonetheless, accurate assessment of food 
and nutrient intake has remained challenging, despite an improvement in methods. Self-
report methods, namely food records, are a mainstay of nutritional epidemiology 
research, 4 with food recall being another popular method. 5 These methods rely on the 
participant to accurately estimate portion size and, for food recall, remember what was 
consumed. The accuracy of these methods have been questioned 6-9 and the problems 
with human recall have been comprehensively outlined. 10 As a result, there remains a 
significant need for methods that are sufficiently accurate to provide researchers with 
good outcome data and to guide health promotion efforts. 
The PortionSize™ app was designed by our laboratory to overcome the limitations 
outlined above, and to guide users to follow specific diets. PortionSize relies on users 
capturing images of their food selection and waste. Food intake data are immediately 
provided since the user relies on built in tools, including templates, to estimate portion 
size. However, despite promising early indications, the PortionSize app has yet to be 
fully validated. Determining the accuracy of PortionSize is vital before users can utilize 
the app to obtain immediate feedback about their food intake. We accordingly aim to 
test the validity of PortionSize during two buffet meals in a controlled laboratory setting 
and compare this to another app that has been adopted widely - MyFitnessPal©, which 
is an electronic food record.
Methods
Study Design
We will recruit adults to use the PortionSize app or the MyFitnessPal during laboratory-
based simulated meals.
Participants and Recruitment
We will recruit 43 adults (approximately equal proportion of men and women) who will 
be randomly assigned in approximately a 1:1 ratio to use PortionSize at the first visit 
(and MyFitnessPal at the second visit), or MyFitnessPal at the first visit (and PortionSize 
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at the second visit). We expect to enroll an approximately equal number of participants 
with body mass indexes (BMI; kg/m2) between 18.5 to 25; 25 to 30; and 30 – 50kg/m2.  
Recruitment will be stratified based on sex and body mass index.

Inclusion criteria include:
o
Male or female, age 18-70 years
o
Body mass index (BMI) 18.5-50 kg/m2
o
Ownership of an iPhone model 6s or later, which the participant is willing 
to use for the study
o
Access to Apple ID, password, and email address and willing to use them 
in the course of the study
o
Willing to use data and any accompanying charges as part of study 
participation
o
Willing to be re-contacted for future research and/or follow-up

Exclusion criteria include 
o
Center employee, as previous reviewers argued that they are not 
representative of the community 
o
Any condition or circumstance that could impede study completion
Procedures
Screening visit/Study Visit 1
In the screening visit, written informed consent will initially be obtained. We will then 
obtain:

Demographics: age, race, ethnicity, sex, employment, income, marital status, 
education level (Appendix A: Lifestyle, Demographics, and Health Questionnaire)

Anthropometrics: height, weight, and BMI
On being deemed eligible, in this within subjects design, participants will be randomized 
to use either PortionSize or my MyFitnessPal at this first visit, with the other app being 
used at the second visit. They will receive training on the app that they will use that day 
to subsequently rate a meal. Training will span up to ~45 minutes. 
Participants will then estimate food intake from a simulated lunch meal; i.e., they will not 
eat food during the meals. The meal will consist of at least three foods, one calorie 
containing beverage, and may contain a vitamin and/or supplement. Participants’ 
energy requirements will be calculated using sex-specific formulas. Energy 
requirements will be multiplied by 1.3 and the food selection for the simulated test meal 
will include 30% of this value, which represents a typical lunch. Plate waste will be 
determined at the individual food item level and will range between 0% and 100%, but 
the distribution will be skewed to the lower end such that mean plate waste is ~5% of 
foods provided, which is slightly higher than actual plate waste from our free-living data 
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(~3%). 11 Simulated food provision and plate waste will be covertly weighed, and 
simulated food intake calculated by difference. 
When participants use PortionSize, they will be instructed to use PortionSize to estimate 
food provision and plate waste. PortionSize will then calculate food intake, with energy 
intake being the primary outcome variable. PortionSize will also transfer the food 
images to the Food Photography Application for expert rater analysis, and these are 
secondary outcome data. When participants use MyFitnessPal, they will enter estimated 
food intake into the app.
Near the end of the visit where participants used the MyFitnessPal app, they will 
complete the MyFitnessPal User Satisfaction Survey (Appendix B) and the 
MyFitnessPal Computer System Usability Questionnaire (MyFitnessPal CSUQ) 
(Appendix C) to quantify satisfaction and ease of use of the MyFitnessPal app. The 
CSUQ is a standardized, reliable, and valid questionnaire originally designed to 
evaluate computer programs12,13 that has been used to quantify the usability of mobile 
phone apps.14,15 Similarly, at the end of the visit where they used the PortionSize app, 
they will complete the PortionSize User Satisfaction Survey (Appendix D), as well as the 
PortionSize CSUQ (Appendix E). Additionally, only after the visit that includes the 
PortionSize app, participants will complete a modified version of a self-administered 
food frequency questionnaire (Appendix F, Diet History Questionnaire, Version 3.0 or 
the DHQ-III).16  Specifically, the DHQ-III was modified such that participants will report 
the presence of vitamins and supplements during the test meal. Thus, only those items 
(vitamins and supplements) of the DHQ-III will be administered, and the instructions will 
ask participants to note if those items were present in the test meal. 
Study Visit 2
Participants will return within approximately three to 14 days to be trained on the app 
not used at the first visit. They will then estimate food intake from another simulated 
lunch meal. This will be conducted exactly as Study Visit 1. Participants will then 
complete either the PortionSize User Satisfaction Survey or the MyFitnessPal User 
Satisfaction Survey, depending on which app they used during Study Visit 2. They will 
also complete either the PortionSize CSUQ or the MyFitnessPal CSUQ. 
Participants then will complete an the User Preference Survey (Appendix G) to 
determine which app (PortionSize or MyFitnessPal) they prefer, think is most accurate, 
etc. 
Outcome measures
The primary analyses assessing equivalence between PortionSize and the criterion 
measures (and MyFitnessPal and the criterion measures), will rely on equivalence 
testing using the Two One-side T-test (TOST)17,18 method. The criterion measure is 
directly weighed foods from the simulated lunch meal. Differences in the observed error 
from PortionSize and MyFitnessPal will be compared with dependent t-tests, with error 
calculated as the difference between each experimental method and the criterion 
variable (e.g., energy intake values from PortionSize minus energy intake values from 
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weighed foods). These procedures will also produce results indicating if the error from 
each method differs from zero. Subsequent regression-based exploratory analyses 
will determine if error from the apps varies by body mass (kg, BMI), age, or sex; and will 
evaluate differences in user satisfaction and preference between the apps. Bland-
Altman analysis19 will be used to test for differences in error variance over levels of the 
variable being measured (e.g., food intake).
Thus, primary endpoints will be:

Energy intake (kcal)

User satisfaction and usability of the app 
Secondary endpoints will be:

Nutrients (e.g., fat, carbohydrate, and protein) and food groups (PortionSize only) 
intake 
o
Only PortionSize has the ability to provide output in food groups due to the 
link with the FNDDS database.  
Exploratory endpoints include the modified Dietary History Questionnaire (DHQ) as a 
comparator for the possible dietary supplement. This specific addition was not an 
outcome included in the grant and was added post award. 
Schedule of procedures
The schedule of procedures is outlined below:
Procedure
Screening and 
Study Visit 1
Study Visit 
2
Informed Consent
X
Demographics, Anthropometrics, Eligibility Evaluation
X
Randomization (to use PortionSize or MyFitnessPal 
first)
X
Training on PortionSize or MyFitnessPal app
X
X
Use of app during simulated laboratory-based meals
X
X
User Satisfaction Survey, CSUQ
X
X
Modified Dietary Questionnaire (DHQIII16)
PortionSize 
visit only
PortionSize 
visit only
User Preference Survey
X
The screening portion of the first visit will last approximately 60 minutes. The remainder 
of Study Visit 1 and Study Visit 2 will last approximately 120 minutes.
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Power calculation
We will recruit 43 participants and we are powered even if we experience attrition of up 
to 10%, resulting in 39 participants finishing both visits. Estimated food intake values 
form the PortionSize (and MyFitnessPal) will be compared to directly weighed values. 
Equivalence tests that follow the Two One-sided T-test (TOST)17,18 method will be used 
with alpha = 0.05 and specified acceptable lower and upper bounds of equivalence 
(error reflects the difference between weighed intake and estimates from either 
PortionSize or MyFitnessPal). Equivalence is set as within ± 6% of the directly weighed 
value. With as few as 39 participants completing the PortionSize and MyFitnessPal 
condition, we have at least 0.80 power to detect equivalence with ±6% error bounds 
(±35.2 kcal). Additionally, with 39 participants completing the PortionSize and 
MyFitnessPal condition, we have power of 0.80 to detect a 46 kcal difference in error 
(effect size = 0.6) between the conditions. Finally, with 39 participants completing the 
PortionSize and MyFitnessPal condition, we have 0.80 power to detect an R2 of 0.17, 
which is acceptable as studies with Bland-Altman analysis find that poor methods of 
measurement frequently have R2 > 0.16.22 
Provisions to Monitor the Data to Ensure the Safety of Subjects
Adverse events will be monitored at each intervention visit. The PI and his co-
investigators will review all data continuously to ensure the safety of each subject.
Withdrawal of Subjects
Subjects may be withdrawn from the study if he/she misses study visits and will be 
notified of their withdrawal via telephone or mail. If a subject voluntarily withdraws from 
the study, no additional data will be collected and they will be considered dropouts in 
the study.
Risks to Subjects
This study involves no greater than minimal risk. The main risk is breach of 
confidentiality, and the PBRC team will work to minimize this during data collection, 
handling, and analysis.  
Potential Benefits to Subjects
Participants may benefit by increased awareness of their portion sizes with various food 
groups. 
Sharing of Results with Subjects
The participants may receive information such as body weight and anthropometrics. 
Those results will be provided to the participant at the end of the study if requested.
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Setting
The Ingestive Behavior, Weight Management, and Health Promotion Laboratory at 
Pennington Biomedical Research Center. 
Compensation
Participants will receive $75 for the successful completion of the study. 
Provisions to Protect the Privacy Interests of Subjects
All attempts will be made to maintain a subject’s privacy. Safeguards such as password-
protected computers and networks have been put in place in order to limit access to 
subject data. Subjects will be given ample time to read over the consent, ask questions, 
and agree to participate in the research study. Subjects may decline to answer 
questions with which they are not comfortable. Each procedure will be explained to the 
subject before it is performed. We will always ensure the privacy of the subjects.
Participants will be advised to read the current version of the Privacy Statement for 
MyFitnessPal provided as a link within the consent form to understand how the 
company will use their information. The current version can be found here:  
https://account.underarmour.com/en-us/privacy_and_terms 
Compensation for Research-Related Injury
No compensation will be provided for research-related injury.
Economic Burden to Subjects
All study-related tests and procedures will be at no cost to the subject. The subject will 
incur transportation costs in getting to Pennington Biomedical Research Center. It is 
also possible that the subject twill incur data charges by using their own smartphone 
during the study. The chances of this occurring can be mitigated by connecting their 
smartphone to WiFi while at the Center. 
Consent Process
A designated and trained staff member will obtain informed consent during the first visit. 
Ample opportunity will be given for the subject to review the consent and ask any 
questions prior to signing the consent form. If subjects wish, they can take the form 
home and return at a different visit. We are aware that consent is an ongoing process.
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