Can any of my sports geek friends (say Christine or Bjarke) answer this:

1) Do you burn more calories biking on a warm (~20°C) day than on a cold day (~0°C) assuming biking happens at the same speed? On the one hand, on the warm day you get warmer which I assume is good for burnination (which is now a word), while on the cold day you need to keep your body temperature and I can feel my muscles are much more tired today even though I didn’t go particularly fast.

2) My fitness thing says I burn less calories now than 10 kg ago (approximately 1200 kcal for 38 km vs 1400 for the same 3 months ago). In that same period my lean mass has stayed more or less constant (I only started measuring fat percentage after building up muscle). Of course, all things else considered equal, lugging around an extra 10kg takes more energy, but it was my impression that the majority of calories burned is due to muscle mass, so I guess the difference reported is mostly bogus and due to (wrong) assumptions about body composition?