deltaWeight is available on the iTunes app store.

I avoided these because I did not want deltaWeight to have an opinion either on what you were doing or how you were doing it. The daily weights and the resulting trend information are useful. But they need to be interpreted based on individual goals, self-knowledge, and possibly guidance from a physician, trainer, or nutritionist.

If I included a lot of interpretive tools (like BMI charts), the utility of deltaWeight would be limited by the utility of those tools. Instead of just reporting weight, the app would end up aligning itself with certain dietary or nutritional strategies, becoming less useful to others.

So deltaWeight is not “non-judgemental” because judging is bad, it is non-judgemental because I feel humans should be doing the judging.

There’s another reason deltaWeight is non-judgemental: it’s because I wanted a more rational approach to weight management.

Other weight logging tools — the Wii Fit is a notorious example — implement encouragement and nagging into their tool. Gain weight when you’re supposed to be losing, and the Wii Fit will insist you contemplate the reasons for your weight gain and give you a little lecture. Lose weight and you’ll get a little patronizing pat on the head. The Wii may have a friendly tone, but I can’t get over the fact that it is an unsensing hunk of plastic and silicon.

Some people might want that, and that’s fine. But I’ve always found the atmosphere around a lot of weight management tools infantalizing, and I suspect a lot of other people — especially those drawn to geeky features like calculated weight trend lines — have the same desire.

There are without a doubt more features that should and will be added to the tool. But only if they make the data more useful or interesting — not if they try to interpret meaning of the data. That’s your business.

I kept looking for diet tools that used this obvious idea. Well, it was obvious to me, anyway. And so I finally gave up and wrote my own.I wrote it on the iPhone because that seemed like the logical choice. Those of us who have them tend to keep them close. I submitted it to the Apple store on Monday, and it’s currently waiting for its App store evaluation.

It’s a pretty simple app: weigh yourself every morning, log the weight in the app. The app does the statistical analysis (an “exponentially smoothed moving average with 10% smoothing”, or so they tell me), draws you a pretty chart, and you can get a sense of what’s really going on with your weight.

These screenshots are real data — my data. I started my current diet and this app at about the same time. The thin, light, jumpy line is my daily weight check. The thick blue line is the smoothed average. The thin line seems to be all over the place, but the thick line shows a steady, if gradual, decline. I was actually pretty discouraged about the diet until I got that moving average feature working. Then I felt pretty good about it.

Two more things. Most of the weight trackers I looked at previously all assumed you wanted to lose weight — and they wanted to help you get there. That’s admirable, but there’s only so much help I want. I don’t particularly want to be encouraged, cajoled, shouted at, or shamed. So this app doesn’t do that. It just tells you where you are.

If you do want the emotional pressure, the Wii Fit should suit you just fine. But it doesn’t do an exponentially smoothed moving average with 10% smoothing.

I also know that people track their weight for many other reasons. Maybe you’re trying to bulk up. Maybe you’re watching out for drug side effects. Maybe you just enjoy numbers. There are lots of reasons you might want to keep track of your weight that have nothing to do with losing or dieting, so this app doesn’t tell you that gaining is bad and losing good. There are no scary red letters, and that’s by design.

∆Weight is available on the app store.