People today are dieting like never before and keeping track of their weight loss is impossible without a bathroom scale, and even then it is difficult to keep paper records of weights over time. Bathroom scales are found in variety of sizes shapes and prices. A bathroom scale may cost anywhere from ten to hundreds of dollars depending on the features that the scale has. In addition to weight monitoring, a bathroom scale may allow a user to monitor body fat and body mass index. The constant monitoring of weight may prevent sudden weight gain that may lead to obesity.


In 1999, an estimated 61 percent of U.S adults are overweight as well as 13 percent of children and adolescents. Obesity among adults has doubled since the 1980’s. In addition, the obesity among children and adolescents has tripled. A report titled The Surgeon General’s Call to Action to Prevent and Decrease Overweight and Obesity states that being overweight or obese may cause preventable diseases and death as often as cigarette smoking (Surgeon General, 2001).


“Overweight and obesity are among the most pressing new health challenges we face today,” says Tommy G. Thompson, secretary of Health and Human services. Some conditions that have increased due to obesity are asthma and type 2 diabetes among children (Food and Drug, 2002).


Bathroom scales are not only used to monitor weight and guard against obesity, they are also used by athletes to measure weight and body fat. The bathroom scales that have the capabilities to measure body fat and body mass index allow athletes to maintain optimum lean muscles. They can also measure body fat and body mass indices accurately, privately, consistently and easily in the privacy of their own home. It is ideal for anyone in a fat-burning, exercise, bodybuilding or weight management program who wants to measure their progress.


In both of these cases keeping paper records of weight, body fat and body mass index over time is important. This is often difficult because people need to have pen and paper available when weighing themselves in addition to the fact that the records need to be stored somewhere. Ideally, the bathroom scale could keep track of this information automatically and allow users to easily retrieve it whenever they needed it.


If the scale automatically kept such records it would be easy for the scale to generate graphs of progress and allow for the records or graphs to be easily exported and used elsewhere. Adding these features does complicate matters some and requires some mechanism to keep different users separate so that records can be meaningful while still allowing more than one person to use the scale. Scales which support multiple users and record keeping exist, but none of them provide a convenient way to get the data off of the scale and into some more useful place.


Our idea is to put a network interface card in the scale so that it can be hooked up to a local area network and provide simple connectivity with computers through a web interface. This concept of web interfaces is used very successfully in small networking devices, such as routers, bridges and print servers. With a web interface many of the problems plaguing current scales are resolved. First, the extra screen space given by most computer monitors these days allows for much easier interaction and provides space to have many records displayed at once, either as a chart or a graph. Secondly, it is much easier to transfer data from the scale to a home computer if the two devices are already connected and interacting via a web interface.


People who are neither in danger of being obese nor athletes can also benefit from using a scale like ScalePlus. Just because a person is not obese and isn’t an athlete does not mean that they are unconcerned with their weight. People concerned with their appearance would most likely want to track their weight in order keep themselves looking their best. Also, keeping records of children’s weight in order to track their grown is an important task that is usually done at the doctor’s office, but keeping redundant, more detailed records at home would help a family keep their own medical records. There are also many more potential users who could benefit from the extra functionality provide by ScalePlus. With this in mind, we have tried to design interfaces which work for all people. Among it’s other features, the ScalePlus will function as a normal bathroom scale allowing anyone to step on it and see their current weight, regardless of whether they have an account making it as easily accessible as a normal scale to people who are not interested in the extra features.



Retail Products


The following products are similar to ScalePlus or were used to develop ScalePlus but do not interface with a computer.


The Easy-to-View Scale with Remote Big-Digit Display transmits weight readings to a remote display. The display mounts on the wall or rests on its built in stand for easy eye-level viewing. The display shows the time and date as well as the weight. Body Mass Index (BMI) indicator determines whether you are over or under weight based on you height to weight ratio. The Body Mass index was recognized by the U.S. Department of Health as the standard for normal values of height and weight. The scale allows four separate user IDs. Each user can store up to seven readings by date and time. An additional guest ID is available but can not store any readings.


The Seca 882 Mommy and Baby Scale with Body Mass Index displays body weight and body mass index for users. This electronic scale with remote display can be utilized for approximately 80,000 weighing operations. The Seca 882 also has a unique “Mommy and Baby” feature that lets a mother weigh herself, then the scale automatically zeros itself so when she picks up her baby, the Seca will accurately subtract the mother’s weight from the combined weight and give the baby’s weight as accurately as if the baby was being weighed alone.


The Brookstone Body Fat Scale with Memory takes the guesswork out of weight and health management. A user is able to track their fitness progress. The body fat scale stores both your weight and body fat percentage readings in memory. The scale compares your results to the last reading and the medically-approved standard. The large digital display is easy to read and use. A user just enters their age, sex, height and activity level. In addition a user must select one of three user modes: Adult, Athlete or Child. The scales stores personal data for up to four different family members to make  future readings. It also recommends daily caloric intake guide for weight management (Greenberg, 2003).


These scales as well as others manufactured by companies such as Tanita, Scale-Tronix and Oregon Scientific, offer some of the same functionality as the ScalePlus but lack the critical component that allows for easy interaction between the scale and a computer.



Academic Papers


The results of several academic papers altered how we thought about developing the ScalePlus. Few papers concerned our project specifically, but many dealt with medical devices in general and even specifically with the interfaces for medical devices. Recently, interface design for home medical devices has become a major area for research. Companies like Intel are developing systems to help the currently aging older adult population. Additionally, the Journal of Biomedical Informatics is holding  special issue on human-centered computing in health information systems (Shneiderman, 2004). This interest has produced many projects which we drew upon in our work.


Using a set of guidelines called Making Medical Device Interfaces More User Friendly helped us to have a specific set of guidelines for our creation of our interfaces (Wiklund, 1998). Many of the principles here mirror the eight golden rules of interface design presented in Designing the User Interface but also provide some specific recommendations for medical devices (Shneiderman, 1998). Stressing the reduction in screen density, number of colors and typographical complexity, these guidelines helped keep our interfaces simple and focused on a task oriented design.


Prior research into designing a generic interface for keeping records of weight, temperature, and blood pressure was done at the University of Maryland and provided useful results for how to visualize and store medical data (MediConnect, 2002). Again, this research is related but still slightly more general than is perfectly applicable to our project.


With this plethora of research in the area, the ScalePlus should fit nicely in a niche close to prior research but pushing the envelope toward simple devices that perform a given task with minimal effort on the user’s part.