No idea about how much runner weigh, but I know if Im wearing shoes and heavy clothes when I weigh in, I will be about 1.5-2kgs heavier.
Looking at your food diary, everything looks ok, other than the full fat milk, unfortunately there IS a big difference between full and skim milk, fat and sat. fat wise and also the ice cream, 4 tbls sounds like a lot? Are they small tablespoons or are they heaped? If they are heaped then that is probably too much. Also, you didnt mention if you are drinking any water. You should aim to drink 2 ltrs of water each day, for the body to function properly, more if you have caffienated drinks or if you are active. I know if I dont drink my water, I will generally stay the same when I weigh in. Do you keep an eye on salt (sodium) intake? Too much salt can cause fluid retention - weight gain, so that may also be the prob. Do you vary your exercise? Maybe try something different (aerobics, dancing, swimming etc) to shake up the body a bit? Also resistance/weight training is as important as cardio (your running etc) is, so maybe try some handweights or weights at the gym? Lol what a mouthful that was!!
I hope you find what your prob is as I know it can be very frustrating!