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Figure 4. Meta-analysis of activity monitors correlation with doubly labeled water

The Calorie Watch: Accuracy and ApplicationsAdam Hoover & Eric R. Muth

Department of Electrical and Computer Engineering and Department of Psychology, Clemson University, Clemson, SC, USA

Bite Technologies, Clemson, SC, USA

Accuracy Data

Self-monitoring has been shown to be one of the most critical aspe

successful weight loss interventions (Burke et al., 2009). Food diari

and dietary recalls are the primary tools used today. These tools ha

heavy user burden making compliance over time challenging. The

Calorie Watch uses Bite Counter technology to derive and present

calorie information to the wearer. The calorie estimates are derived

from bites and the Mifflin-St. Jeor formula for resting energy

expenditure (REE) adjusted for physical activity level (PAL) to determ

caloric needs to set the target calorie goal.

Weight Loss/Maintenance

Applications

Data are stored on the

device long-term and can

be downloaded to a PC

for analysis. The screen

shot on the left shows a

calendar of eating

activities over a 1 month

period. Patterns can

quickly be observed. By

clicking on the calendar a

week view pops up with

more detail on the

number of bites taken or

calories consumed.

Figure 8. Overview of monthly record of eating activities

Observation

Real-Time Feedback

Figure 9. Detailed record of eating

Bites to Kilocalories

Calorie Watch Accuracy Compared to Physical Activity Monitors

To study the relationship between bites and kilocalories, a total of 83 people wore the Calorie Watch for two weeks (Scisco, "Sources of Variance

in Bite Count", PhD Dissertation, Psychology Dept, Clemson University, May 2012). Ground truth kilocalories were measured using the ASA24

dietary recall. Over 4000 meals were evaluated, approximately 50 meals per person. The above figures show the data from two participants. Each

data point is one meal. The bites-to-kilocalories correlation for the plot on the left is 0.4 (Fig. 1) and for the plot on the right is 0.7 (Fig. 2). Over

75% of participants had a correlation above 0.4. While there is obviously noise in the kilocalorie-bite relationship for a single bite, due to the

energy density of the food being eaten and natural variability in bite size, the relationship shows some stability at the meal level.

There are a large variety of physical activity monitors, including simple pedometers, consumer-grade devices like the Fitbit and Nike's Fuel Band,

and professional-grade devices like the Actigraph and Actiwatch. These devices provide a measure of energy expenditure. The Calorie Watch is

similar but is the only device of its kind to provide an automated measure of energy intake. How good is the measure? The plot above on the left

(Fig. 3) shows the histogram of ASA24 calorie-Calorie Watch calorie correlations for all 83 participants in the study described above. To provide

context, the plot above on the right (Fig. 4) shows a histogram of correlations found in a meta-study evaluation of 41 studies that compared

energy expenditure as measured by physical activity monitors to doubly labeled water (Westerterp & Plasqui, 2007, "Physical Activity Assessment

with Accelerometers: An Evaluation against Doubly Labeled Water", in Obesity, vol 15, pp 2371-2379). As can be seen, the Calorie Watch provides

a measure of energy intake comparable in quality to the measure of energy expenditure provided by physical activity monitors.

Figure 1. Participant with a r= 0.4 bites-calories correlation Figure 2. Participant with an r=0.7 bites-calories correlation

Figure 3. Calories measured by the Calorie Watch correlated with ASA24

The device software allows you to

custom configure the device to set the

display mode (calories/bites), to enter

the calorie calibration from the abovecalorie calculator and to set an

auditory alarm to go off either at a meal

target calories or a day target.

The device is watch-like and through a

simple display and interface provides

feedback to the wearer while they are

eating and reminds them how much they

have eaten for the day.Figure 6. Interface for custom device configuration Figure 7. Picture of the Calorie W

Figure 5. Calorie Calculator to custom set the bites-calorie transform