At end of year, I've got a working carbs management for my needs. Data acquisition is primarily manual. I may take pictures of meals. Or I may record it immediately. Most often I look at pictures or remember meals, manually figure out grams of carbohydrates, and create a simple table. This table is processed through R, and graphically displayed. I look at the graphics to decide whether I need to change something, and as a reward of seeing things stay on track.
The R code is small:
colnames( df) <- c( "Date", "Meal", "carbs")
plot <- qplot( Date, carbs, data=df, shape=Meal, color=Meal, ylab="Carbohydrates (gm)") + geom_bar( stat="identity")
which generates a nice picture:
From this you can see that I usually have the same thing every day for breakfast. Day to day variability is pretty hgh, but I'm holding daily carbs satisfactorily. The running average is somewhere between 100 and 150 gms daily.