ive kept a food log for several years now in little notebooks...i hate doing things online or with apps...i write down the date, whether i'm on my TOM or not, exercise and what type of exercise i do, length, difficulty etc, and my foods along with calories and carbs....sometimes i write in my weight but not always as i try not to become obsessed over the scale
i also write down if i occasionally don't get enough sleep or there's tons of drama going on because i want to look back and see if that affected anything
i've tracked every day that way for more than 2 years now