Ability of the LeanScreen App to Accurately Assess Body Composition

Article (PDF Available)inComparative Exercise Physiology 13(1):59-66 · January 2017with 267 Reads
DOI: 10.1249/01.mss.0000535610.04677.17
Cite this publication
Abstract
Introduction: Waist-to-hip ratio (WHR) and percent body fat (%BF) are commonly used to assess body composition in health and wellness settings. While there is only one commonly used method for measuring WHR, %BF can be determined many ways. However, the accuracy, cost, and ease of use of these methods vary greatly. The LeanScreen app is a new method designed to determine WHR and %BF using photographs. Purpose: This study was designed to assess the accuracy of the LeanScreen app to determine WHR and %BF against laboratory-validated methods. Eighty subjects (40 males; 40 females) participated in this study. Waist-to-hip ratio was manually measured and %BF was determined using the BOD POD. Photographs of each subject were taken from the front and side with the LeanScreen app according to the procedures demonstrated by the program software. Results: There was no significant difference in WHR between the LeanScreen app (.81 ± .078) and manual (.81 ± .087) WHR measurement (r=.83). Additionally, it was found that 73 subjects (91%) were within the 95% confidence intervals of the mean. Overall, %BF was significantly underpredicted by the LeanScreen app compared to the BOD POD (20.2 ± 7.74 vs. 21.6 ± 8.77). Although there was a high correlation between the two methods (r=.82), only 35 subjects (44%) were within ± 3% of BOD POD derived %BF and there was a high degree of variability between methods (SEE=5.1). Conclusion: Based upon the results of this study, the LeanScreen app accurately determines WHR, but does not accurately determine %BF on an individual basis.
[Year]
59
Marx et al. (2017) Int J Res Ex Phys. 13(1):59-66.
Sponsored by:
Exercise and Sport Science Program
Western State Colorado University
Ability of the LeanScreen App to Accurately Assess Body Composition
Ray Marx1, John P. Porcari1, Scott Doberstein1, Richard Mikat1, Abigail Ryskey1, Carl Foster1
1Department of Exercise and Sport Science, University of Wisconsin-La Crosse, La Crosse, WI, USA
Abstract
Introduction: Waist-to-hip ratio (WHR) and percent body fat (%BF) are commonly used to assess body
composition in health and wellness settings. While there is only one commonly used method for
measuring WHR, %BF can be determined many ways. However, the accuracy, cost, and ease of use of
these methods vary greatly. The LeanScreen app is a new method designed to determine WHR and
%BF using photographs. Purpose: This study was designed to assess the accuracy of the LeanScreen
app to determine WHR and %BF against laboratory-validated methods. Eighty subjects (40 males; 40
females) participated in this study. Waist-to-hip ratio was manually measured and %BF was
determined using the BOD POD. Photographs of each subject were taken from the front and side with
the LeanScreen app according to the procedures demonstrated by the program software. Results:
There was no significant difference in WHR between the LeanScreen app (.81 ± .078) and manual (.81 ±
.087) WHR measurement (r=.83). Additionally, it was found that 73 subjects (91%) were within the 95%
confidence intervals of the mean. Overall, %BF was significantly underpredicted by the LeanScreen app
compared to the BOD POD (20.2 ± 7.74 vs. 21.6 ± 8.77). Although there was a high correlation between
the two methods (r=.82), only 35 subjects (44%) were within ± 3% of BOD POD derived %BF and there
was a high degree of variability between methods (SEE=5.1). Conclusion: Based upon the results of this
study, the LeanScreen app accurately determines WHR, but does not accurately determine %BF on an
individual basis.
Key Words: BOD POD, Body Fat, Obesity, Overweight
[Year]
60
Marx et al. (2017) Int J Res Ex Phys. 13(1):59-66.
Sponsored by:
Exercise and Sport Science Program
Western State Colorado University
INTRODUCTION
Body composition is an important component
of health-related fitness because of the
relationship between excess body fat and
chronic disease. Individuals classified as
overweight or obese have a higher risk of
developing a variety of diseases, including
Type 2 diabetes, cardiovascular disease, and
stroke1. Epidemiologically, the degree of
overweight or obesity are often classified by
body mass index (BMI) or waist-to-hip-ratio
(WHR) because both methods are fast and
easy to determine2. Body mass index is
calculated by dividing body weight in
kilograms by the square of height in
centimeters, WHR is determined by dividing
the circumference of a person’s waist at the
narrowest part by hip circumference of at the
widest part3. There are a variety of other
ways to measure body composition including
skinfold measurements (SF), bioelectrical
impedance (BIA), hydrostatic weighing (HW),
dual x-ray densitometry (DEXA), near infrared
interactance (NIR), and the use of a BOD POD
(Life Measurement Inc., Concord, CA), but the
accuracy, ease of use, and cost of using these
methods can vary greatly. Personal trainers,
nutritionists, physicians, and other
professionals who use these methods of
assessment would benefit from an
inexpensive, accurate, and simple way of
measuring body composition.
PostureCo (PostureCo, Trinity, FL) has
developed an app for a phone or tablet that
uses photographs to assess percent body fat
(%BF), BMI, and WHR. PostureCo’s
LeanScreen app incorporates photographs
taken from the front and side to determine
these measurements. According to
PostureCo’s website, the LeanScreen app can
predict these measurements to within 3%
accuracy4. To our knowledge, the accuracy of
the LeanScreen app has never been
independently tested and validated. The
purpose of this study was to assess the
accuracy of the LeanScreen app to assess %BF
and WHR by testing it against laboratory-
validated methods.
METHODS
Participants
Subjects for this study were 40 male and 40
female volunteers, with a wide range of body
types and ages. Descriptive characteristics of
the subjects are presented in Table 1. The
purpose and procedures of the study were
explained to subjects and each subject
provided written informed consent prior to
undergoing any testing procedures. The study
was approved by the University of Wisconsin-
La Crosse Institutional Review Board for the
Protection of Human Subjects.
Table 1. Descriptive characteristics of subjects (N=80).
Parameter Female (n=40) Male (n=40)
Age (yr) 35.3 ± 11.78 29.2 ± 12.89
Height (cm) 166 ± 6.60 179 ± 7.30
Weight (kg) 68.3 ± 10.94 82.8 ± 14.70
Data are reported as mean ± standard deviation.
[Year]
61
Marx et al. (2017) Int J Res Ex Phys. 13(1):59-66.
Sponsored by:
Exercise and Sport Science Program
Western State Colorado University
Experimental Design
Height and weight were measured using a
mechanical scale (Pellstar L.L.C. Health O
Meter, McCook, IL). Height was measured
in meters to two decimal points and weight
was measured to the nearest kilogram with
one decimal point. Waist-to-hip-ratio was
determined by dividing the circumference
of the subject’s waist at the narrowest part
by the circumference of their hips at the
widest protrusion of the buttocks as
recommended by the American College of
Sports Medicine3. Circumference
measurements were made to the nearest
centimeter using a steel tape measure. The
waist measurement was made at the
narrowest part of the waist, just above the
iliac crest. The subject stood with their feet
shoulder width apart, exhaled completely,
and the tape was wrapped around their
body parallel with the ground. The tape was
snug to the waist to ensure accurate
measurements, but was not tight to the
point of moving or displacing the skin. Hip
measurements were made in the same
manner except they were taken at the
widest protrusion of the buttocks. Percent
body fat was measured to one decimal
point using a BOD POD, which measures the
amount of air displaced by a person in a
known volume of space. Although
hydrostatic weighing is considered the gold
standard for measuring %BF5 research by
Vescovi et al6 , McCrory et al7, Fields et al8,
Fields, Hunter and Goran,9 and Nunez et al10
have shown the BOD POD to be virtually
identical to hydrostatic weighing as a means
of measuring %BF, with correlations ranging
from .90-.97.
Pictures of each subject were taken using
the LeanScreen app on an iPad (Apple Inc.,
Cupertino, CA) following the procedures
provided by PostureCo, Inc. Two
photographs were taken from 12 feet away;
one from the front and the other from right
side of the subject’s body. Reference lines
were drawn onto the photos in the
software program according to the
directions given by the LeanScreen app.
Using the photograph from the front-view,
reference points were placed at each side
of the neck, halfway between the sternum
and umbilicus, at the level of the umbilicus,
and at each side of the hips at the widest
location. Reference points from the side-
angle photograph were placed at the same
locations as the front-view photograph. The
subject’s height, weight, age, and gender
were also entered into the software
program.
For all measurements, participants wore
tight-fitting clothing (swimsuit or spandex
shorts and a sports bra) and a swim cap.
The reason for this is two-fold: tight
clothing allows for more accurate
placement of reference points on the
LeanScreen app, and the wearing of a swim
cap minimizes air displacement of the
subject’s hair during the BOD POD
measurements.
[Year]
62
Marx et al. (2017) Int J Res Ex Phys. 13(1):59-66.
Sponsored by:
Exercise and Sport Science Program
Western State Colorado University
Statistical analyses
Standard descriptive statistics were used to
determine the baseline characteristics of the
subjects. Paired-samples t-tests were used to
compare %BF determined by the BOD POD
and the LeanScreen app, and WHR
determined by manual circumference
measurements compared to the LeanScreen
app. Pearson product-moment correlations
were used to compare the relationship
between BOD POD and LeanScreen %BF, as
well as between manual WHR measurement
and LeanScreen WHR. Standard error of the
estimate (SEE) was determined using linear
regression analysis. All data were analyzed
using the Statistical Package for the Social
Services (SPSS Inc., Chicago, IL) version 25.
Alpha was set at .05 to achieve statistical
significance.
RESULTS
Overall, %BF was significantly underpredicted
by the LeanScreen app compared to the BOD
POD (20.2 ± 7.74 vs. 21.6 ± 8.77). A plot of the
data are presented in Figure 1. The
correlation between the LeanScreen and BOD
POD %BF was r=.82 and the SEE was 5.1%.
A plot of the differences between %BF
determined by the BOD POD and the
LeanScreen app is presented in Figure 2.
Upon examination of the calculated
differences observed in Figure 2, it was noted
that people with a lower %BF (<10%)
appeared to be overpredicted by the
LeanScreen app, and people with a higher
%BF (>30%) appeared to be underpredicted
by the LeanScreen app. Thus, subjects were
divided into three groups based on %BF as
calculated by the BOD POD and means were
compared for subjects with a %BF of <10%,
10%-30%, and >30%. It was found that for
subjects with a %BF <10%, the LeanScreen
significantly overpredicted %BF by an average
of 4% (12.0 ± 1.63 vs. 8.0 ± 1.74). For subjects
between 10%-30% body fat, there was no
significant difference between the
LeanScreen and BOD POD (18.5 ± 6.52 vs.
19.3 ± 5.12). In subjects with %BF >30%,
LeanScreen significantly underpredicted %BF
by an average of 5.7% (28.9 ± 5.26 vs. 34.6 ±
3.03).
The LeanScreen app claims to be accurate
within 3 percent of actual %BF. Of the 80
subjects, only 35 (44%) had a %BF predicted
by LeanScreen that was within ± 3% of BOD
POD values.
Overall, there was no significant difference in
WHR as determined by the LeanScreen app
compared to manually measured values. The
correlation between the LeanScreen app and
manual measurement was r=.83 and the SEE
was 0.04. Because the LeanScreen app rounds
to only one decimal point when determining
WHR, data are shown in straight lines on the
vertical (y) axis, whereas manually measured
WHR values were reported to two decimal
points on the horizontal (x) axis. A plot of the
data is presented in Figure 3.
Differences between WHR as determined by
the LeanScreen app compared to manually
measured WHR values are presented in
Figure 4. The horizontal lines represent the
95% confidence intervals around the line of
identity. Upon examination of the graph, 73
(91%) of subjects fell within this range.
[Year]
63
Marx et al. (2017) Int J Res Ex Phys. 13(1):59-66.
Sponsored by:
Exercise and Sport Science Program
Western State Colorado University
Figure 1. Relationship between percent body fat (%BF) determined by the BOD POD and the LeanScreen app.
Figure 2. Difference between percent body fat (%BF) determined by the BOD POD and the LeanScreen app.
Dotted lines represent ± 3% difference between the LeanScreen app and the BOD POD.
This research hasn't been cited in any other publications.
  • Health risks of being overweight Retrieved from https
    National Institute of Diabetes and Digestive and Kidney Diseases. (2012, December). Health risks of being overweight. Retrieved from https://www.niddk.nih.gov/healthinformation/health-topics/weightcontrol/health_risks_being_overweight/Pages/h ealth-risks-being-overweight.aspx
  • Article
    Full-text available
    The aim of this study was to identify the usefulness of body mass index (BMI), waist circumference (WC) and waist-to-hip ratio (WHR) in screening for obesity in teenagers by using the receiver operating characteristic (ROC). To select the sample set in this cross-sectional study, a stratified random sampling approach was utilized. Weight, height, WC, hip circumference and body fat percentage (BFP) were measured in 1118 children of both genders (597 boys and 521 girls), aged from 10 to 15 years old. Percentiles of BMI and Centers for Disease Control and Prevention-United States (CDC-US)-growth chart for boys and girls aged from 10 to 15 years old were presented. ROC analyses were then used to evaluate the performances of three anthropometric indices; BMI, WC and WHR had strong positive correlations with BFP (r = 0.49-0.77) in both girls and boys within indicated age group. The area under the curves (AUCs) were high in both girls and boys for BMI, 0.795 and 0.893, respectively, and WC, 0.767 and 0.853, respectively, and were a little lower, 0.747 and 0.783, respectively, for WHR. In conclusion, this study demonstrates that the prevalence of being overweight and obese among teenagers of both sexes in our data set does not differ from CDC-US-growth chart. In addition, BMI and WC are two important predictors for teenagers to become overweight and obese, while WHR is less useful for this purpose.
  • Article
    A new air displacement plethysmograph, the BOD POD (BP), was evaluated in comparison to hydrostatic weighing (HW). Sixty-eight adult subjects (26 F, 42 M) varying widely in age (range 20-56 yr), ethnicity, and fatness participated in this study. Same-day test-retest reliability was assessed in a subsample of 16 subjects (9 F, 7 M) and validity was assessed in all subjects (N = 68). The test-retest coefficients of variation (CV) for %FAT measured by BP (%FATBP) and HW (%FATHW) were not significantly different (1.7% +/- 1.1% and 2.3% +/- 1.9% for BP and HW, respectively (mean +/- SD)), indicating excellent reliability for both methods. Validity of percent fat measured by the BP (%FATBP) was also excellent. The mean difference in %FAT (BP - HW) was -0.3 +/- 0.2 (SEM), with a 95% confidence interval of -0.6 to 0 %FAT. The regression equation (%FATHW = 1.86 + 0.94 %FATBP; r2 = 0.93, SEE = 1.81) was not significantly different from the line of identity (%FATHW = %FATBP), and did not differ by gender. These findings indicate that the BOD POD is a highly reliable and valid method for determining %FAT in adult humans in comparison to HW. This new method has several advantages over HW in that it is quick, relatively simple to operate and may be able to accommodate special populations such as the obese, elderly, and disabled.
  • Article
    Over the past decade, considerable attention has been paid to accurately measuring body composition in diverse populations. Recently, the use of air-displacement plethysmography (AP) was proposed as an accurate, comfortable, and accessible method of body-composition analysis. The purpose of this study was to compare measurements of percentage body fat (%BF) by AP and 2 other established techniques, hydrostatic weighing (HW) and bioelectrical impedance analysis (BIA), in adults. The sample consisted of healthy men (n = 23) and women (n = 24). %BF was measured by AP, HW, and BIA. In the total group, %BF(AP) (25.0+/-8.9%) was not significantly different from %BF(HW) (25.1+/-7.7%) or %BF(BIA) (23.9+/-7.7%), and %BF(AP) was significantly correlated with %BF(HW) (r = 0.944, P < 0.001) and with %BF(BIA) (r = 0.859, P < 0.01). Compared with HW, AP underestimated %BF in men (by -1.24+/-3.12%) but overestimated %BF in women (by 1.02+/-2.48%), indicating a significant sex effect (P < 0.05). The differences in estimation between AP and BIA and between BIA and HW were not significantly different between the sexes. AP is an accurate method for assessing body composition in healthy adults. Future studies should assess further the cause of the individual variations with this new method.
  • Article
    Full-text available
    Air displacement plethysmography (ADP) may provide a partial alternative to body density (Bd) and therefore body composition measurement compared to conventional hydrodensitometry (Hd) in children. As there are no evaluation studies of ADP in children, this study had a two-fold objective: to compare Bd estimates by ADP and Hd; and to compare fat estimates by both ADP and Hd to fat estimates by another reference method, dual energy X-ray absorptiometry (DXA). Obesity Research Center, St. Luke's/Roosevelt Hospital, New York, USA. One hundred and twenty subjects (66 females/54 males) who ranged in age from 6-86 y and in body mass index (BMI, kg/m2) from 14.1-40.0 kg/m2 met study entry criteria. Cross-sectional study of healthy children (age < or = 19 y) and adult group for comparison to earlier studies. Each subject completed ADP, Hd, and DXA studies on the same day. Only subjects with subjectively-judged successful Hd studies were entered into the study cohort. There was a high correlation between Bd by ADP and Hd (Bd Hd = 0.11 + 0.896 x Bd ADP; r = 0.93, SEE = 0.008 g/cm3, P < 0.0001), although the regression line slope and intercept differed significantly from 1 and 0, respectively. Additional analyses localized a small-magnitude Bd bias in the child (n = 48) subgroup. Both ADP and Hd %fat estimates were highly correlated (r > 0.9, P < 0.0001) with %fat by DXA in child and adult subgroups. Bland-Altman analyses revealed no significant %fat bias by either ADP or Hd vs DXA in either children or adults, although a bias trend (P = 0.11) was detected in the child subgroup. With additional refinements, the air displacement plethysmography system has the potential of providing an accurate and practical method of quantifying body fat in children as it now does in adults.
  • Article
    Full-text available
    Whole body air-displacement plethysmography (BOD POD), a new body composition technique, was validated against hydrodensitometry (UWW) in 67 women wearing a one-piece swimsuit (OP) who represent a wide range of body fatness and age. Additionally, the effect of trapped isothermic air in clothing while in the BOD POD was examined by comparing different clothing schemes (a one-piece swimsuit (OP), two-piece swimsuit (TP), a hospital gown (HG), and a hospital gown previously included in a volume calibration (GC)) in a subset of 25 women. Cross-sectional data analysis. 67 healthy Caucasian females. Body density g/cm3 (Db) by BOD POD and UWW. In 67 females UWW Db (1.030+/-0.020 g/cm3) was higher (P<0.01) than BOD POD Db (1. 028+/-0.020 g/cm3). This is a difference of 1.0% fat. The R2 was 0. 94, SEE was 0.005 g/cm3 and the regression between Db by UWW and BOD POB did not significantly deviate from the line of identity. In the subset group of 25 subjects, OP Db (1.040+/-0.014 g/cm3) and TP Db (1.040+/-0.014 g/cm3) were significantly lower (P<0.01) than UWW Db (1.044+/-0.014 g/cm3) or a difference of 1.9% fat. The R2 was 0.86 and the SEE was 0.005 g/cm3 and the regression between Db by UWW and both OP and TP did not significantly deviate from the line of identity. HG Db (1.056+/-0.016 g/cm3) and GC Db (1.037+/-0.016 g/cm3) were significantly different (P<0.01) from UWW Db (1.044+/-0. 014 g/cm3). This difference in density translates to a difference of 5.5% and 3.2% fat respectively. The regression between Db by UWW and both HG and GC significantly deviated from the line of identity. This study supports the use of the BOD POD as a substitute for UWW. However, caution should be made in using the BOD POD if subjects are clothed in anything other than a tight fitting swimsuit.
  • Article
    This study was designed to compare the accuracy and bias in estimates of total body density (Db) by hydrostatic weighing (HW) and the BOD POD, and percent body fat (%fat) by the BOD POD with the four-compartment model (4C model) in 42 adult females. Furthermore, the role of the aqueous and mineral fractions in the estimation of body fat by the BOD POD was examined. Total body water was determined by isotope dilution ((2)H(2)0) and bone mineral was determined by dual-energy x-ray absorptiometry. Db and %fat were determined by the BOD POD and HW. The 4C model of Baumgartner was used as the criterion measure of body fat. HW Db (1.0352 g x cm(-3)) was not statistically different (P = 0.35) from BOD POD Db (1.0349 g x cm(-3)). The regression between Db by HW and the BOD POD significantly deviated from the line of identity (Db by HW = 0.90 x Db by BOD POD + 0.099; R(2) = 0.94). BOD POD %fat (28.8%) was significantly lower (P < 0.01) than %fat by the 4C model (30.6%). The regression between %fat by the 4C model and the BOD POD significantly deviated from the line of identity (%fat by 4C model = 0.88 x %fat by BOD POD + 5.41%; R(2) = 0.92). BOD POD Db and %fat showed no bias across the range of fatness. Only the aqueous fraction of the fat-free mass (FFM) had a significant correlation with the difference in %fat between the 4C model and the BOD POD. These data indicate that the BOD POD underpredicted body fat as compared with the 4C model, and the aqueous fraction of the FFM had a significant effect on estimates of %fat by the BOD POD.
  • Article
    Full-text available
    The primary purpose of this investigation was to compare estimations of percentage body fat (%fat) using air displacement plethysmography (ADP) and hydrostatic weighing (HW) in a heterogeneous (age and %fat) sample of the population. Of secondary importance was to determine whether there were differences between the two methods among lean (n = 32), average (n = 34) and overweight (n = 29) subsets of this sample. A total of 95 adults (men 27, women 68) ranging in age from 18-52 years volunteered for this study. Test-retest reliability for %fat ADP (n = 16) was 0.99 with a technical error of 0.75%fat and a coefficient of variation of 3.4%fat. Mean body density using ADP [1.048 (SD 0.016) g.ml-1] was not significantly different when compared to HW [1.049 (SD 0.017) g.ml-1], which corresponded to a non-significant difference in %fat [22.5 (SD 7.3)% ADP compared to 22.0 (SD 7.6)% HW]. Regression analysis provided the equation: %fat HW = 0.9121%fat ADP + 1.5123; r = 0.88, SEE = 3.6, which did not differ significantly from the line of identity. Data for the subsets revealed a significant overestimation of %fat ADP [16.4 (SD 4.8)%] compared to HW [14.1 (SD 3.2)%] (P = 0.001) for lean individuals while no difference was found in the average [21.9 (SD 4.4)%fat ADP compared to 22.0 (SD 3.4)%fat HW] or overweight [29.9 (SD 5.5)%fat ADP compared to 30.8 (SD 4.1)%fat HW] subsets. Measuring %fat by ADP is a highly reliable method and valid when compared to HW for a heterogeneous sample of adults. The ADP method requires little expertise to operate, is quick to perform, and may be more accommodating for certain individuals compared to HW. However, in this study ADP was less valid for lean individuals. Further investigation is warranted to determine the bias of this method for subsets of the population which may be outside the average range of %fat (men 15.4%-22.0%, women 18.4%-28.5%).