And non-foods can affect you too. Taking 2 ibuprofen makes me gain a pound overnight, and recently I returned to town at the height of maydays blooming and gained 6 lbs overnight due to histamine production and the antihistamines I took. But the weight (and mayday flowers) came off overnight 3 days later in a rainstorm. In addition to logging foods, it is helpful to note anything else out of the ordinary, to make such correlations and keep on plan to see how variable your weight can be and why while eating "perfectly". Most of my first ~200 diets were sabotaged when I gave up in frustration because I didn't think they were working; now I don't worry because I understand my natural variability. I still take ibuprofen and antihistamines, but limit them to when I really really need them. Quercetin & bromelain work well for mild allergies, but I take the antihistamines when I start soaking one tissue per minute.