February 25, 2009

You Ask, I Answer: Calorie Discrepancies on Food Labels

Why does the nutritional information on labels of the (seemingly) same product, but from different companies, have different data?

The one that I noticed today was when I bought Hodgson Mill's oatbran.
It says 40 grams has 120 calories, but Mother's oat bran says 40g is 150 calories. Shouldn't these be the same?

They both state that the only ingredient in the box is oat bran.

Another example (that got me started on this) was canned black beans.

Again, the serving side listed on the can is always approximately the same (I've even checked the weight, not just the half cup measurement) and the calories listed can range from 90 to 130, depending on the brand.

Do you know why this is?

I understand that companies have some fudge-room for their nutritionals, but these examples seem like there shouldn't be that much of a difference.

-- Michelle Pope

(location withheld)

Ah, welcome to the twisted maze that is calorie labeling!

This is an excellent question, as it gives significant insight into labeling laws and regulations.

Come on in and sit a spell, though, because this can be initially confusing to the untrained eye.

First of all, remember that calorie figures higher than 50 can be rounded off to the nearest 10-calorie increment.

In other words, if a serving of cereal adds up to 134 calories, it can legally be displayed on the label as 130.

Similarly, a serving containing 156 calories is often shown as 160 calories for simplicity's sake.

Now we get to the more complicated issues.

Although you often see references to carbohydrates containing 4 calories per gram, they technically contain 3.6 calories per gram.

The "4 calories per gram" figure is commonly used -- and referred to everywhere, including this blog -- in order to facilitate in-your-head multiplication and estimation.

Additionally, since protein technically provides 4.2 calories per gram, the logic is that by portraying both those nutrients as containing 4 calories per gram, final estimates are very close to actual totals.

That said, some companies arrive at their calorie totals by allocating 4 calories to each gram of carbohydrate in their food, while others -- and this is completely legal, by the way -- allocate 3.6 calories per gram.

On top of that, all macronutrient figures are rounded off. In other words, a serving of food containing 29.5 grams of carbohydrates shows up as containing 30.

So, company #1 may choose to keep it simple and multiply that rounded figure (30 grams) by the rounded-up "calories per gram" figure (4 calories per gram) and come up with 120 calories.

Meanwhile, company #2 can instead opt to multiply the technical figures (29.5 grams of carbohydrate x 3.6 calories per gram) for a grand total of 106 calories!

Then we have the issue of fiber, which comes into play with both of your food examples.

If food companies choose to, they may leave out grams of carbohydrates from insoluble fibers in their final calculations.

Taking all that into consideration, you can see why the same amount of the same food does not always yield the same food label.


Kate, RD said...

Hey Andy - great job at describing such a complex issue!

WifeMomChocoholic said...

Thanks! I have often wondered about that very thing.