Macro nutrients and calories don't add up

jefmcg

The macro nutrients and total calories for cos lettuce don't match.

If you add up the calories of the macro nutrients for cos lettuce, you don't get the number displayed 3.5×4 + 3.3×4 + 0.8×9=34.4 not 47.

If you look at the daily total (if all I ate that day was six cups of chopped lettuce 😱 ) it seems that the carbs are closer to 10g than the 3g shown on the details page.

muffinlicious

I've noticed that often times the calories get rounded for certain foods such that the macronutrients don't get added up correctly, and as a result I usually need to go 100-150 calories over my daily goal to hit my macronutrient targets. I've never considered it a huge deal because I've still been able to lose weight, but I'll admit that the difference between 3.3 and 10 grams of carbohydrates is kind of a lot. . . it'd be useful to know where you could report discrepancies like this.

jefmcg

"it'd be useful to know where you could report discrepancies like this."

I had assumed in the bug report section of their user forums (aka here) but....

Karen_Cronometer

Hi there,

There are a couple of things to note about calculating energy in foods.

For lab analyzed data we often have more accurate energy estimates for each of the macronutrients than the average 4/4/9 kcal/g for protein/carbs/fat.

For example, Food Data Central shows the calculated energy values use to estimate the energy in Lettuce, Cos or Romaine, Raw:
Protein - 2.44 kcal/g
Carbs - 3.57 kcal/g
Fat - 8.37 kcal/g

Second, the energy from carbohydrates is calculated using the amount of total carbs, rather than the net carbs. For your selected serving size that would be 9.3 g of carbs to calculate the energy value.

For branded products, nutrition information is taken from the nutrition label on the package. The numbers on the package are typically rounded values so there will be a little bit of error in these numbers so they will never be a precise as the lab analyzed sources.

jefmcg

"Second, the energy from carbohydrates is calculated using the amount of total carbs, rather than the net carbs. For your selected serving size that would be 9.3 g of carbs to calculate the energy value."

Um, why? Fibre is not digested, so why would you include it in total calories?

(I keep recommending cronometer to people because it's db is so accurate, but every time it do, I find weird behaviour)

Karen_Cronometer

The energy factors provided by Food Data Central take into account the energy coming from all sources of carbohydrates. There is some energy coming from fibre and we do not want to under represent the amount of energy in the foods you log in Cronometer.