If a can of coke has 39 grams of sugar and that amount of sugar equals 151 calories, how come the coke has 139 calories? What happens to the missing equivalent of kcal?

Question

If a can of coke has 39 grams of sugar and that amount of sugar equals 151 calories, how come the coke has 139 calories? What happens to the missing equivalent of kcal?

In: 7307

Answer 1

There are two systems that the FDA has approved for determining the caloric content for a nutrition label:

1) **Atwater General**: The Atwater General system gives a blanket caloric content of 4 calories per gram of sugar or protein and 9 per gram of fat.

The Atwater General numbers are what you generally see cited pretty much everywhere because they’re straightforward and easy to use. But they’re general approximations.

Atwater General works well when you’re mixing foods together – if you put an apple, chicken thigh, milk, and some lettuce in a blender you’ll get a disgusting mix where the calories *probably* average out to be *about* 4 per gram of carbohydrate and protein and 9 per gram of fat. But if you’re looking at a food made up of a single, pure calorie source – such as a banana or a bag of sugar – then the Atwater General numbers will end up pretty far off from the amount of calories that are actually in the thing you’re eating.

2) **Atwater Specific**: The Atwater Specific system is a *gigantic* table of caloric values for different food types. The amount of calories that you get out of a gram of carbohydrate, fat, or protein is actually pretty difficult to calculate, because what constitutes a carbohydrate, fat, or protein can vary wildly between different foods.

Even something like “sugar” can have a wildly varying composition of fructose, sucrose, glucose, and other simple carbohydrates depending on the source you get it from.

Then you have to factor in that these chemicals are all mixed together – sometimes you get more or less energy out of a gram of carbohydrate because there is something else its paired with in the food that makes it more or less likely to burn in the laboratory test they’re using to determine caloric content.

Since you’re drinking a refreshing Coca-Cola®, you’re not in the apple/chicken/milk/lettuce smoothie situation where the calories per gram are *probably* averaging out. Instead, you’re in the other situation where you have a single calorie source – high fructose corn syrup. HFCS is listed at ~3.7 calories per dry gram in the Atwater Specific table. That would put 39 grams of HFCS at 144 calories. Per FDA guidelines on rounding, that 144 would then be rounded down to 140, which is the number of calories listed on your ice cold Coca-Cola®.

And if you’re really worried about calories, try the new Coca-Cola® Zero Sugar. It has the same great taste as the Coca-Cola® Classic that you love without any of the calories or sugar.