Fact-checked by Dr. Anthony Gustin, DC, MS.
Written by Emily Ziedman
Knowing how to read food labels correctly is an essential part of healthy eating. Understanding concepts like serving size versus portion size and percent daily value puts you in the driver’s seat when it comes to your food choices.
As crucial as nutrient know-how is, there are a few tricks to the trade that many people overlook. And depending on your health goals — whether it’s weight loss, lower blood pressure, or simply staying in ketosis — you’ll want to keep a close eye on nutrition labels.
A Short History of Food Labels
Back in the day, when your grandmother was in the kitchen cooking from scratch, there was no need for nutrition labels. It wasn’t until the 1960s that the idea of nutritional labeling even made sense.
Some packaged food companies would list their sodium or calorie content, but those foods were considered “for special dietary uses” by the FDA.
As people grew more health savvy and the link between diet and health became more clear, consumers started to demand more nutrition information on their packaged foods.
Can you imagine walking into a grocery store full of packaged foods and not seeing any nutrition info?
The FDA began to call for nutrition information on food packaging. Manufacturers, seeing a marketing opportunity, responded by adding unregulated health claims on packaging. Things like, “extremely low in saturated fat.”
The First FDA Guidelines
This unregulated health claim marketing continued for a short time, but the FDA quickly stepped in to initiate guidelines for companies to follow. The first call to action was that if a manufacturer wanted to make a health claim, they also had to include a nutrition facts label to back up the claim.
The 1960s and ‘70s were like the wild west of food labeling. So the FDA finally came up with the Nutrition Labeling and Education Act (NLEA). The NLEA is what we see today on the back of packaged foods.
The purpose of the NLEA was threefold:
- Clear up confusion around nutrition labeling
- Help consumers choose healthier foods
- Give food manufacturers incentive to improve the nutritional quality of their packaged foods
The NLEA was passed in 1993 and stated that, with a few exceptions, all packaged foods needed to have nutrition labels.
The nutrients that required labeling included:
- Calories from fat
- Total fat
- Saturated fat
- Total Carbohydrate
- Dietary fiber
- Vitamin A
- Vitamin C
Since the 1990s some changes have been made, including[*]:
Nutrients no longer required on the label:
- Vitamin A
- Vitamin C
- Calories from fat
- “Added sugars”
- Vitamin D
- Trans fat
Food Labels: The Terminology
Today, all food labels look pretty much the same, give or take a few nutrients that the manufacturer wants to add.
But not all labeling terminology is self-explanatory. In order to truly understand what you’re eating, you’ll want to get familiar with what each of the following means:
The serving size is one of the most important aspects to pay attention to on the food label because it can change the meaning of the entire food label.
For instance, if you just look at the “Total Carbohydrates” line and it says “10 grams,” that’s one thing. If the serving size for that package is 4, however, then you’ve actually got 40 grams of total carbs on your hands.
In other words, every nutrient on the label represents the nutrients in one serving, not the entire package.
When developing serving sizes, manufacturers are supposed to use amounts that reflect what people actually eat, not the amount they should be eating.
When serving sizes were initially set back in the 1990s people were eating a lot less then they do today. Because of this, the 2016 updated NLEA has increased most serving sizes to match what is now commonly consumed[*].
An example is ice cream — back in the ’90s a serving size of ice cream was ½ cup.
The updated NLEA now has one serving of ice cream at ⅔ cup[*].
Calories are measurements of energy. One calorie (or Kcal) is the amount of energy it takes to heat one kilogram of water by one degree Celsius. Food scientists use this measurement to determine the energy value of different foods.
When you look at the calories in your packaged foods, they don’t represent nutrient density or weight; it’s simply the amount of energy that the food holds.
To go a little deeper — every macronutrient is composed of atoms, and each of these atoms is held together by energy.
- 1 gram of protein = 4 calories (4 units of energy)
- 1 gram of carbohydrate- 4 calories (4 units of energy)
- 1 gram of fat = 9 calories (9 units of energy)
Notice how it takes more energy to hold a gram of fat together? That’s why high-fat foods tend to be higher in calories.
% Daily Value
Your Percent Daily Values, or DV, shows the average percentage of a specific nutrient you need for the entire day, assuming you consume about 2,000 calories per day.
That means, if a serving contains a DV of 10% vitamin C, that’s 10% of the vitamin C you need for the day, according to the FDA.
RDI stands for Reference Daily Intake. RDI is the amount of a specific nutrient that the government deems necessary for you to consume daily.
These numbers are based on population data across every demographic of “healthy” people in the U.S. So, according to their calculations, most everyone in the U.S. should get a certain percentage of the nutrients on every food label. Then they use the RDI to determine the % Daily Value (DV) on your packaging.
DRV, aka Daily Reference Values, are for any nutrients or other compounds that don’t have an RDI. The DRV is based on what the FDA and most research suggest a “healthy” person should consume daily[*].
The ingredient list is usually found below or next to the nutrient breakdown. This is an important, and often overlooked part of the food label.
Manufacturers must list all the ingredients. However, many ingredients go by several different names.
If you have a sensitivity to any particular food, it’s important to know all the names that food can go by.
For instance, hydrolyzed wheat protein is a form of gluten. And casein is a dairy protein that a lot of people are sensitive to.
How to Read Food Labels
Step #1: Check the Serving Size
The most critical step in reading a food label is checking the serving size.
You want to make sure that you’re calculating the nutrition based on the amount of food you’re actually consuming. For instance, the serving size for most cereals is ⅔ cup. When you pour a bowl of cereal, do you stop at ⅔ cup? Unless you’re a small child, probably not.
The number of servings is also important. You may be surprised that the bag of chips you typically buy actually has 5 servings, not one.
All nutrient values on the label are based on the serving size, so getting this one right is crucial.
In the case of the cereal, if you typically eat about 1.5 cups you would want to double the rest of the nutrients to get an accurate count.
Step #2: Check Out the Total Calories
You shouldn’t get too hung up on calories, but knowing how many calories a food contains can help you determine if this is a snack or if it’s a meal.
If you’re someone who typically consumes 1500 calories a day, then a 500 calorie food may be a whole meal. However, if you’re consuming 2500 calories a day, a 500-calorie food could be a hearty snack.
Step #3: Check Out the Macronutrient Ratio
Get an idea of what the macronutrient ratio is of your food.
Look at the total carbohydrates, total protein, and total fat. Depending on your goals, you may want higher or lower numbers for each of these.
If you see that carbs are the highest value or if carbs are over 5 grams per serving, it’s most likely not a keto-friendly option.
Step #4: Check the Fat Profile
The fat section of the food label contains three parts:
- Total fat
- Saturated fat
- Trans fat
The trans fat portion was added only a couple years ago as authorities began to understand the detriments of trans fat, and how it can affect your health[*].
In general, you want to see a higher ratio of fat when you’re following a ketogenic diet. Saturated fat is fine, but trans fats are a no-go.
Step #5: Check the Carbohydrate Profile
The carbohydrate section will be broken down into four parts:
- Total carbohydrate
- Dietary fiber
- Total sugars
- Added sugars
Total carbohydrate will include all the fiber, sugar, sugar alcohols, and complex carbohydrates in the food. To break this down into more meaningful information you want to first look at the total sugars.
Many foods will have naturally occurring sugars, like some snack bars that have dried fruit. In general, you want to see the total sugars low, 5 grams or fewer is ideal for most people.
Added sugars signify that the manufacturer threw in some extra sugar that was not naturally occurring in the food. Added sugars is never a good idea when you’re trying to get into or maintain ketosis. And it’s rarely a good idea when you’re following other diets.
Avoid added sugars at all costs.
Dietary fiber accounts for the insoluble or soluble fiber in your food.
Most fiber bypasses your digestive system and helps feed good gut bacteria in your colon. Because it doesn’t act like a normal carbohydrate — aka, it doesn’t get broken down into glucose — most people don’t count it as a normal carb.
Instead, it’s common to subtract the grams of fiber from the total carbohydrates to come up with the net carb count.
Step #6: Check Out the Daily Values
The daily value gives you an estimate of how those specific nutrients contribute to your daily needs based on a 2000 calorie per day diet.
First, pay close attention to the sodium to potassium ratio.
A good goal would be to see as close to an even ratio of these two micronutrients, with a higher potassium level being ideal.
A low daily value for any nutrient is 5% or less, while a high daily value is 20% or more.
Keep in mind that the numbers you see on the label are for the average person eating a 2000 calorie a day diet and may not translate to your diet directly.
The 2015 dietary guidelines recognized iron, calcium, potassium, and vitamin D as nutrients of concern for underconsumption in the United States.
For this reason, calcium and iron remained on the nutrient panel, and the FDA added potassium and vitamin D. Seeing high levels of these nutrients on the label is typically a good thing[*].
Step #7: Check The Ingredient List
This step is just as important as checking out the serving size.
Many people go straight to the nutrients panel and skip over the ingredient list. But your food item could have a stellar nutrient panel, and still contain processed junk that your body doesn’t recognize.
How to Read a Food Label When You’re on a Keto Diet
The above guidelines are essential for everyone, but if you’re following a keto diet, there are a few other aspects of the food label you want to stay aware of.
The carb section on a nutrition label is even more important if you’re on a keto diet.
First, check out the total carbohydrates.
Many people like to calculate “net carbs” as opposed to simply using total carbohydrates because your body processes and stores different carbs in different ways.
To calculate net carbs, subtract any carbohydrate that your body isn’t actually absorbing. This includes dietary fiber and a portion of sugar alcohols.
Next, look for sugar alcohols.
Sugar alcohols aren’t in every packaged food, but they’re in a lot of “low-carb” or “keto” snack items as a sugar replacement.
Sugar alcohols include products like xylitol, erythritol, sorbitol, mannitol, isomalt, lactitol, and hydrogenated starch hydrolysates.
Your gut only partially absorbs sugar alcohols, and it depends on the type of sugar alcohol.
The rule for diabetics is to subtract only half the amount of sugar alcohols to play it safe. So a calculation would look like[*]:
Net carbs= Total carbs- dietary fiber – ½ sugar alcohols.
#2 Macronutrient Ratio (For Keto)
The macronutrient ratio becomes doubly important when you’re following a ketogenic diet.
Keeping the net carb count low is a must, but you also want to make sure you’re getting enough protein and fat to balance out your meal or snack.
If you know your optimal ketogenic macros then you can use that as a reference. If you’re unsure, check out this Keto Macronutrient Calculator to determine the best ratio for you.
Another thing to keep in mind is that the macronutrients are in grams, not percentages. Each gram of fat is more than double one gram of protein or carbohydrate, so if you see a nutrition label that shows:
- Calories: 85
- Total Fat: 5 grams (9 calories per gram)
- Total Carbohydrate: 5 grams (4 calories per gram)
- Total Protein: 5 grams (4 calories per gram)
That’s not a 33% fat, 33% carb, 33% protein ratio. It’s actually 52% fat, 24% carb, 24% protein.
Aim for healthy fats and protein to make up a majority of your calories.
#3 Low-Carb Ingredients to Watch Out For
So many packaged food products contain ingredients you don’t need.
Just because the macronutrients look keto-friendly doesn’t mean that snack is good for you.
Do Food Labels Matter?
Hopefully, you pack your keto meals with plenty of real, whole veggies, healthy fats, and high-quality protein. But for the days when all you crave is a conveniently packaged snack, make sure to read your labels.
Look for added sugar, preservatives, and ingredients you can’t pronounce.
And don’t forget to take serving sizes into account.
You may not be able to trust food labels 100%, but they do provide some guidance. And as always, for a truly stellar keto diet, stick to whole foods.