First, congratulations on dropping 100 pounds! That is a remarkable achievement for anyone.
Next, I think our stories sound somewhat similar. I, too, look at data and outcomes, and as I know I'm lazy, I'm constantly turning to technology to make the mundane business of data logging as painless as possible. I have a wifi connected scale that also measures body fat, and logs every reading automatically. I weigh myself daily. And yes, I also recognized that lots of people get discouraged by the daily up and down fluctuations in weight. My motivation there is to look at the three month chart, and to see the weight line steadily descending into a healthier range. It doesn't matter that this morning I was up a pound over the previous day when the overall trend line is still on a good trajectory. Every individual measurement shows a bump up or down from the previous day; the insignificance of any one day's measurement is obvious to anyone when looking at the data in aggregation.
I also have logged everything (well, everything except for a few days while on a vacation) I have eaten since I started this journey. What helps me there is a smartphone app that scans barcodes, looks up foods in a crowdsourced database, and populates the day's journal with the data. Yes, I do have to evaluate and select the data more carefully than I'd like, but it's still easier than typing in a pile of numbers. Knowing what went in enables me to stop before I reach the day's limit. Being honest with the data is critical there. So far it seems that I could maintain this pace indefinitely, but I do see how it occasionally requires returning to the touchstone of motivation.
I know that nutrition info is always an average; so I don't get all worried about exact portion sizes, or logging a few carrots or lettuce unless they exceed a reasonable threshold. I'm interested only in a good outcome, not precision in data measurements. Along with this I do know that I have to either carefully log or avoid certain types of foods entirely - sweets and snacks are not something I can write off as not worth logging.
The activity tracker study was a bit odd. I am interested and motivated to use technology and data to drive positive changes, but I ironically ended up in their control group. So I wore their tracker, but did not have access to their step counts. I continued to wear the personal tracker I've worn for the past three years, but in the interest of the study I deliberately ignored it. After the study ended, I looked and could see that my daily counts were averaging much lower than they were when I was actively trying to meet a daily step goal. Incidentally, I also discovered that the wrist-worn tracker is far less accurate in step-counting than the hip-worn tracker.
One of the biggest hurdles I had to overcome at the beginning of this was entrusting my personal health data to random companies operating cloud services. How do I know that my data won't be used against me in some way? But I decided that my long-term health concerns had to trump the fears of unknown (and possibly imaginary) consequences.
Another thing that is important to me is that I don't have a plan, but a goal. I didn't start with an artificial "drop 60 pounds by New Years" resolution; instead I know I have to continue to lose weight until I reach the target weight my doctor and I agreed to. So far, I've lost 50 pounds in the past 7 months, with about 15 to go. And as long as the one month slope of the weight line remains negative, I have high confidence I'll get there.
Finally, buying new clothes was not nearly as motivating as afterwards when I emptied my closet and donated every single stitch of old clothes to a local charity. Now I know that if I gain weight, it's going to cost me a fortune to buy a size larger! :-)