Thanks!
I was 83.5 kg again this morning. It's a good sign that I have been around this weight several days now, so that it's not just an anomaly, an outlier.
Some other results: I can run much better now. Last week I ran 2 km on the treadmill with a speed of 18.0 km/hour. Incredibly fast, I didn't know that I could do that (and I exercised the days before that (so not at 100%), so I should be able to go even faster/longer). Would be cool to do the 5k that's part of my triathlon in 2 weeks in less than 20 minutes (so faster than 15 km/hour on average). Seems like a realistic goal now.
I also notice that more girls look to me, even better, some even stare at me. Sometimes it may be because I am running like a crazy man in the park, jumping over benches, boulders and down stairs, and taking sprints up hills (jep that's my style, I like to turn my running into a bit of free running

- it's interesting though that as you get lighter you can jump much further, and as you jump more you become more in control of your body and less afraid to miss a jump).
Phase 1: losing weight (go near 75), build exercise routine
The challenge: losing weight in a steady and healthy way, creating an exercise routine and sticking with it.
Result: my weight will be the same as when I was 18 and my speed/endurance will be great. I will, however, have lost some muscle in the process.
Starting position: 106 kg when I was 28, 98 kg when I was 30 (6 months ago), which I treat at my new starting position because it's when I chose to start again.
Progress: 83.5 kg now, so I've lost 14.5 kg since last December. Only 8.5 kg to lose.
Phase 2: start strength training, further improve lifestyle (cooking, sleeping)
The challenge: learning how to do strength training and building a routine, start making actual gains (entire body), making cooking regularly and improving my sleep quality and quantity.
Result: muscle and strength gain, more energy due to improved lifestyle.
Starting position: Though I may start improving these aspects of my lifestyle a bit earlier, I will officially start with this goal when I am 75 kg. At that weight, the muscle that I have will be very defined, but I will also have lost some and I could certainly use some.
Progress: I have yet to start.
End goal (there will be more phases in between): I will first optimize my body for triathlon speed (I will see if I can maybe get in the top 3 of some races), and later (when I am ready to move on) I will build more muscle mass, making me a bit slower, but stronger, which of course looks good, but may be useful for other sports that I may try.