Having completed one week with the GoWear fit on my arm nearly 24 hours/day, I now have enough data to begin drawing conclusions about its usefulness. I'll break down my review into nutrition, exercise energy expenditure, non-exercise energy expenditure, and sleep.
GoWear Fit's nutrition functionality is hardly unique. It provides a web-based mechanism for tracking your daily nutritional intake, just like myriad other products and sites. Its UI is probably in the 70th percentile for online food logs, which makes it a mediocre food log but a great addition to a comprehensive calorie management system.
In 2005 I logged every single food/drink item that entered my body into a spreadsheet for the entire year. It was quite a chore, but the take-aways were invaluable. It was readily apparent from the data that the #1 contributing factor to my inability to reduce body fat was consumption of empty calories from alcohol. More specifically, the few evenings of heavy binge drinking (wine dinners a the Petroleum Club or late nights clubbing/bar hopping) would create massive calorie surplusses (2,000+) that would wipe out weeks of modest calorie deficits. I modified my behavior to drink more in moderation and the following year shed 10 pounds of body fat with no other modifications to my fitness or diet plans.
Online tools make the food logging process much easier than entering everything manually into a spreadsheet so I was eager to give this one a whirl. Although I constantly had to battle error messages telling me that I had been logged off, I was ultimately able to enter each food item I consumed each day, drawing from a large database of pre-existing entries, and get a great breakdown of caloric and nutritional content. The task of food logging itself is quite onerous so I will now use averages from the last week to estimate future intake. Here are a few take-aways from my end-of-week analysis:
1. Food logging is absolutely invaluable and should be done, if not constantly, regularly. It's amazing to see what we put into our bodies and how it differs from what we think we're putting into our bodies. Furthermore, the simple act of measuring caloric intake induces behavioral change, causing food loggers to forego that late night snack because they know they'll have to log it.
2. This actually has an unintended negative side effect: I found myself going back to the same foods over and over again to avoid having to enter new custom foods into the food log. This results in lower dietary variety and I'm a big believer in the positive nutritional benefits of dietary variety. Still, I believe the net effects of food logging are quite positive.
3. I consume ~120 calories per day more than I estimate in my spreadsheet.
4. I consume ~1/2 the Recommended Daily Intake of cholesterol for my 3500 calorie/day diet--that's more or less a good thing!
5. However, I also consume ~2x my RDI of sodium and only ~2/3 my RDI of potassium and calcium. Clearly there is room for improvement here. The vast majority of that sodium is coming from dining out so I need to have heightened awareness when making my choices at restaurants.
6. I consume ~10% protein, ~50% carbs, and ~40% fat. Much of the fat and the sodium come from my cheese addiction (Allez Suisse!), so I need to reign that in a bit. My target will be 15% protein, 60% carbs (good, whole ones of course), and 25% fat.
My nutrition clearly needs some work so I'll do another food log soon to show improvements.
I remove the GoWear fit for swimming (It isn't water proof.) and beach volleyball (I doubt it's sand proof, given how insidious sand from the courts tends to be!) but I leave it on for strength training, running, cardio machines, etc.
For activities such as running and walking, the GoWear fit estimates caloric expenditure that is pretty close to the estimates provided by my Garmin Forerunner 305 GPS/heartrate monitor. That is encouraging for accuracy (of both devices) but by itself it doesn't add much usefulness for the GoWear fit.
The real advantage comes when engaging in activities for which I don't use the GPS/heartate monitor, such as playing Wii or ping pong. For these types of activities I've traditionally gone to my favorite online calorie calculator and estimated my expenditure based on my weight and the nearest activity I can find. I strongly prefer the GoWear fit for this type of measurement, though, as it measures your actual exertion, which may vary a great deal during any such activity. I'll still have to use calculated estimates for swimming and beach volleyball, but I now have much greater confidence in my data for all other activities.
Although the GoWear fit and my spreadsheet of estimates largely agreed on my caloric expenditure during intense exercise, they disagreed vehemently on my total burn each day. On average the GoWear fit estimated that I burned ~550 fewer calories than I had estimated. That's a big difference! Over a week, that amounts to a full pound of body fat of difference!
So which is right? I'm inclined to believe the GoWear fit because it calculates net expenditure at a much finer granularity. It knows, for example, whether or not I've slept less and, hence, burned more calories than a day during which I've slept more (all other things being equal). It knows whether or not I've gotten up only five times from my desk all day and, hence, burned fewer calories than I would have if I'd been up 20 times. It knows if I've been on my feet all evening at an event and, hence, burned more calories than I would have if I'd been sitting on my couch watching Harry Potter movies.
However, the data is kind of damning. According to GoWear fit, I finished the week with a surplus of ~1900 calories, which would account for the addition of ~1/2 pound of fat. According to my spreadsheet of estimates, I finished the week with a deficit of ~3000 calories, or almost one pound of fat lost. Using a three-day moving average of my body fat (as tested on my Tanita scale/body composition monitor and adjusted based on periodic measurements with a Bod Pod), I indeed lost about a pound of fat during the week.
A week is a pretty small sample set for something like body composition, which can vary wildly with, among other things, hydration. Accordingly I'll keep these two systems running in parallel for the rest of the year to see how it plays out. Either way, I'd rather have a calorie tracking system that underestimates my expenditure rather than overestimating it.
An awesome feature for the GoWear fit would be a system that adapts its estimates of your expenditure based on your actual body fat changes over time. That's what I've done with my spreadsheet and, as shown here, it's pretty accurate.
Also a serious shortcoming in the GoWear fit is the fact that it really just tracks weight which, as we all know, is a poor metric of fitness. BMI isn't really any better. I know most people don't have body composition scales at home but it would be great if GoWear fit let those of us who do enter those figures in addition to weight. Until then I will always have to maintain a separate spreadsheet.
I am pleasantly surprised with the GoWear fit's sleep tracking function. I tend to hydrate a lot at night (maybe because of all that sodium I'm taking in during the day!) so sometimes I'll wake up in the middle of the night to go to the bathroom. This week I noted the times that this happened and compared them with the data from the GoWear fit. Sure enough, it recognized easily that I was not sleeping during those times and counted it against my sleep efficiency measurement.
I'm not sure how useful this feature is per se but I think it's cool and I think it's accurate. I'm getting a little over 6 hours of sleep each night with a 91% sleep efficiency. Not bad, I think that's enough--but I could always use more!