How to Read Food Nutrition Data Correctly
How US nutrition labels work: serving sizes, the 4-4-9 calorie rule, % Daily Value, the rounding rules that let some foods say "0", and what to check first.
Start With the Serving Size
Every number on a nutrition label is for one serving, so check that first. US serving sizes are set by FDA rules based on how much people typically eat at one time, and they're shown in both a household measure (such as 1 cup) and grams.
If you eat twice the serving, double every number. Many packages that look like one portion, like a bottle of juice or a bag of chips, now list nutrition both per serving and per package to make this easier.
Where the Calories Come From
Most labels work out calories with the Atwater general factors: 4 calories per gram of protein, 4 per gram of carbohydrate, and 9 per gram of fat. Alcohol has about 7 calories per gram.
So a food with 10 g protein, 30 g carbs, and 5 g fat has about (10 × 4) + (30 × 4) + (5 × 9) = 205 calories. Labels may come out a little different because some manufacturers use more specific factors, and fiber provides fewer calories than other carbohydrates.
What % Daily Value Means
The % Daily Value (%DV) shows how much one serving contributes to a day's total, based on a 2,000-calorie diet. A quick rule of thumb from the FDA: 5% DV or less is low, and 20% DV or more is high.
- Sodium: Daily Value is 2,300 mg.
- Added sugars: Daily Value is 50 g.
- Dietary fiber: Daily Value is 28 g.
- Saturated fat: Daily Value is 20 g.
Why Some Labels Say "0"
FDA rounding rules allow small amounts to be listed as zero:
- Under 5 calories per serving can be listed as 0 calories.
- Under 0.5 g of fat, trans fat, or sugar per serving can be listed as 0 g.
- Under 5 mg of sodium per serving can be listed as 0 mg.
Sugars and Added Sugars
"Total sugars" includes sugars naturally present in foods like milk and fruit. "Added sugars," listed underneath, counts only sugar added during processing, plus syrups, honey, and concentrated juices. Dietary guidelines recommend keeping added sugars under 10% of daily calories, which is the line to watch.
Reading the Ingredient List
Ingredients are listed in order of weight, from most to least. If sugar, or several kinds of sugar under different names (cane sugar, corn syrup, dextrose, honey), appear near the top, the food is high in added sugar.
Allergens must also be declared. In the US, the major allergens are milk, eggs, fish, shellfish, tree nuts, peanuts, wheat, soybeans, and sesame.
Common questions
Is 5% Daily Value a lot?
No. The FDA describes 5% DV or less as low and 20% DV or more as high.