Here's some tips for measuring food with a kitchen scale.
Always measure in grams (g). The application uses grams only.
If your scale has "ml" they are effectively the same as grams.
Use the scale Tare button.
Feel free to eat negative amounts of food.
Negative numbers are very useful for removing the weight of containers.
Do not save the weight of containers (plates, glasses) so that you can subtract it later.
Dishes that look the same may have significant weight differences.
After months of doing this, I found out that two bowls that look identical may easily differ by 50g.
They may have a slight difference in thickness, that I only notice if I look carefully.
Examples
A glass of water
Put the empty glass on the scale
Press Tare
Put water in the glass
Read the amount from the scale
A plate of food, already served
Put the plate with the food on the scale
Press the Tare button.
Oftentimes the plate may obscure the scale reading, so I find it easier,
to zero the scale with the plate on it, and read the weight after removing the plate.
Remove the plate from the scale and read the amount. It will be negative.
Enter this amount, without the negative sign, as the amount you eat in the application
After you finish eating it, measure the empty plate again, the same way.
Eat the same food as before, but enter the weight of the plate, with the negative sign, as the amount.
This will subtract the weight of the plate from the weight of the food that you entered before.