How to Read a Nutrition Facts Label When You Eat Less (Plus EU and Mexican Labels)

To read a Nutrition Facts label, start with the serving size and the number of servings in the package, because every number below them refers to one serving. Then use the %DV column: 5% or less of a nutrient per serving is low and 20% or more is high^[1]. When your appetite is small, add one more step: work out the protein and fiber per 100 calories.

I start with the US label, then show how I read it when eating less, with five real foods from our database. At the end I cover the European and Mexican labels, which you’ll find on many imported products. The overall eating plan is in what to eat on GLP-1 medications.

The Nutrition Facts label, line by line

The FDA’s guide breaks the label into four parts^[1]:

1. Serving information. Servings per container and serving size, in cups or pieces followed by grams. Serving sizes are standardized so that similar foods can be compared, and they reflect the amount people typically eat or drink. Every number on the label refers to one serving: eat two and you double everything, including the %DV.
2. Calories. Energy per serving. The label uses 2,000 calories a day as a general guide; your needs may be higher or lower.
3. Nutrients. The FDA lists saturated fat, sodium and added sugars as nutrients to get less of. Dietary fiber, vitamin D, calcium, iron and potassium are nutrients to get more of.
4. % Daily Value. How much one serving contributes to a day’s reference amount.

The Daily Values behind the %DV, from the FDA’s Daily Value table^[3]:

A few details that change how you read it:

• Total vs added sugars. Total Sugars includes sugars naturally present in milk and fruit plus any added sugars. The line “Includes 7g Added Sugars” means 7 g of the total were added. Total sugars have no %DV^[2].
• Protein usually has no %DV. It is required only when the package makes a protein claim or the food is for children under 4^[1].
• Dual-column labels. Some packages larger than one serving, which could be eaten in one sitting or several, must show two columns: per serving and per package^[1].

How to read a label when your appetite is small

On a GLP-1 medication such as semaglutide (Ozempic, Wegovy) or tirzepatide (Mounjaro, Zepbound), people eat less. The 2025 nutrition advisory on GLP-1 therapy, from four US scientific societies, flags the risk of inadequate nutrient intake from eating less. It calls for ensuring nutrient adequacy within an often substantially lower-calorie diet^[13]. The label helps with that if you read it per calorie, not only per serving. This is how I do it:

1. Protein per 100 calories

Divide the grams of protein by the calories and multiply by 100, both from the same column. For reference points, I borrow the EU’s claim rules in Regulation 1924/2006. A “source of protein” needs at least 12% of its calories from protein, which is 3 g per 100 kcal. “High protein” needs 20%, or 5 g per 100 kcal (my conversion, at 4 kcal per gram)^[5]. The advisory suggests lower-volume protein foods such as fish, eggs, Greek yogurt and cottage cheese^[13]. The protein calculator gives you a daily starting point, and how much protein is in an egg and 24 more foods has examples per serving.

2. Fiber per 100 calories

Same math. The fiber Daily Value is 28 g on 2,000 calories^[3], so the average works out to 1.4 g per 100 kcal (my calculation). If you eat fewer calories and still aim for 28 g, each 100 kcal has to carry more fiber. The advisory encourages fiber from foods, increased gradually^[13]. The fiber calculator adds up your day with foods from our database.

3. Sodium relative to calories

The WHO recommends less than 2,000 mg of sodium a day for adults^[15]; the FDA’s Daily Value is 2,300 mg^[3]. Neither figure depends on how much you eat. My own shorthand borrows Mexico’s warning-label threshold of 1 mg of sodium per calorie^[8]: a 2,000-calorie day at that ratio adds up to exactly 2,000 mg. When a product’s sodium in mg is higher than its calories, I count it as a big bite of that budget. It’s a rule of thumb of mine, not an official cutoff.

4. Calories you drink

The advisory counsels avoiding sugar-sweetened beverages. It also notes that some people meet their protein targets with high-protein shakes or other fortified products^[13]. Using the USDA values on our cola page and counting 1 ml as 1 g, a 12 fl oz (355 ml) can has 149 kcal and 35.3 g of sugars, with no protein or fiber^[16]. If all of that sugar is added, it’s 71% of the added-sugars Daily Value (my calculation). The hydration guide covers fluids.

5. Serving vs package

Multiply by what you actually eat. If you eat half the package, it’s half of the “per package” column, or the per-serving numbers times the servings you ate.

If you’d rather skip the math, the filling foods finder filters and sorts our foods by protein or fiber.

Five real foods, per 100 calories

These are five foods from our database, with values from USDA FoodData Central^[16]. The per-100-kcal columns and the %DV figures are my calculations.

Greek yogurt vs skyr. Both clear the “high protein” bar easily, but skyr gives twice as much protein per calorie. Their “sugars” are lactose, which counts toward Total Sugars but not Added Sugars on a plain product^[2]. More in skyr vs Greek yogurt.

Oats vs corn flakes. Nearly the same calories per 100 g, but oats have more than twice the protein per calorie and almost four times the fiber. Corn flakes have 1.49 mg of sodium per calorie, above the 1 mg rule; 30 g gives 171 mg with only 1.8 g of protein. See rolled oats vs corn flakes.

Butter cookies. Six small cookies, about 30 g, bring 140 kcal and 17% of the saturated fat Daily Value, with 1.8 g of protein. USDA reports 20.2 g of total sugars per 100 g but doesn’t say how much is added^[16]; a US label would^[2].

If you buy European products: the EU label

Under Regulation (EU) 1169/2011, the nutrition declaration is mandatory on most prepackaged foods. It has seven items, always per 100 g or 100 ml: energy, fat, saturates, carbohydrate, sugars, protein and salt. The adult reference intakes are 8,400 kJ / 2,000 kcal, 70 g fat, 20 g saturates, 260 g carbohydrate, 90 g sugars, 50 g protein and 6 g salt. Three differences from the US label^[4]:

• Per portion is optional. When given, the label must state the portion size and how many portions the package holds.
• “Sugars” never separates added sugars. It includes all mono- and disaccharides, lactose and fruit sugar included.
• Salt, not sodium. Salt equals sodium × 2.5, so 1 g of salt is 400 mg of sodium (my conversion). Fiber is optional.

Many packs in Spain, France and other countries also carry the Nutri-Score, a voluntary A to E logo. Per 100 g, it scores against energy, saturated fat, sugars and salt, and in favor of fruit, vegetables and legumes, fiber, protein and olive, rapeseed or walnut oil. The Spanish food agency (AESAN) says it is meant to compare similar products and does not cover the degree of processing^[6]. A revised algorithm, stricter on sugars and salt^[7], has applied since January 1, 2024, with a two-year transition^[6].

Mexico’s warning seals (and the rest of Latin America)

Mexico’s NOM-051 puts black octagons on packaged foods with added sugars, fats or sodium that cross the limits in its Table 6. The seals have been on packs since October 1, 2020. Until September 2025, only the nutrients tied to what was added were assessed: added salt meant sodium only. Since the third and final phase began on October 1, 2025, any added sugar, fat or sodium means every profile in Table 6 is checked^[8].

For drinks, the calorie seal also applies at 8 kcal or more from free sugars per 100 ml (2 g), even below 70 kcal. Free sugars are those added by the manufacturer plus those in honey, syrups and fruit or vegetable juices. Two legends target children: “CONTIENE EDULCORANTES, NO RECOMENDABLE EN NIÑOS” (contains sweeteners, not recommended for children) and “CONTIENE CAFEÍNA EVITAR EN NIÑOS” (contains caffeine, avoid for children). Since April 1, 2021, packs with a seal or the sweetener legend can’t use characters, cartoons, celebrities, athletes, pets or games aimed at children^[8].

With USDA’s figures, I calculate that the corn flakes above would carry “EXCESO CALORÍAS” and “EXCESO SODIO”, assuming added salt. The cola would carry “EXCESO CALORÍAS” and “EXCESO AZÚCARES”, assuming all its sugar is added: its sugars supply about 40 kcal per 100 ml. Plain skyr, with nothing added, would carry none. Other countries use their own versions: Chile’s Law 20.606^[9] (2012) requires “high in” labeling, Argentina’s Law 27.642^[10] (2021) uses “EXCESO EN” octagons, and so does Colombia’s Resolution 2492^[11] (2022), without a calorie seal. Peru’s Supreme Decree 012-2018-SA^[12] uses “ALTO EN” (high in) octagons.

What a label doesn’t tell you

How processed a food is. Neither the Nutrition Facts panel nor the Nutri-Score measures it. The ingredient list, in descending order of weight^[4], is the only clue on the package.

How filling it is. Holt and colleagues (1995) fed 240 kcal servings of 38 foods and found large differences, from croissants (47) to boiled potatoes (323), with white bread as the reference (100). Satiety went with heavier servings, more protein, fiber and water, and less fat. Corn flakes scored 118^[14]. No label shows this, but protein, fiber and calories per 100 g are the best clues it gives you. More in the science of satiety.

How it sits with you. The 2025 advisory notes that fatty or high-fiber foods can be harder to tolerate early in GLP-1 treatment^[13]. That isn’t on the panel either.

Eating well, not eating as little as possible

Reading labels is a way to choose better, not to eat the minimum or to fear a number. If checking labels makes you anxious, if you’re cutting out whole food groups or skipping meals to make up for eating, talk to your doctor or a registered dietitian. MedlinePlus notes that eating disorders are serious mental health conditions and that getting help matters^[17].

Frequently asked questions

How do you read a nutrition label step by step?

Check the serving size and servings per container first, then calories, then the %DV of saturated fat, sodium, added sugars and fiber: 5% or less is low, 20% or more is high^[1]. On a small appetite, also divide protein and fiber by calories and multiply by 100.

What is the difference between total sugars and added sugars?

Total Sugars includes sugars naturally present in milk and fruit plus any added sugars. Added Sugars are those added during processing, from syrups and honey, or from concentrated fruit or vegetable juices^[1]. Only added sugars have a Daily Value: 50 g^[3].

What does %DV mean on a food label?

It’s the share of a day’s reference amount that one serving provides, based on 2,000 calories. It doesn’t add up to 100% down the column. 5% DV or less per serving is considered low and 20% DV or more is considered high^[1].

What do the black octagon warning labels mean?

They’re front-of-pack warnings used in Mexico and several Latin American countries. In Mexico, a packaged food with added sugars, fats or sodium gets one for each limit it crosses: calories, sugars, saturated fat, trans fat or sodium. Separate legends warn about sweeteners and caffeine for children^[8].

Is Nutri-Score better than warning labels?

They do different jobs, and each authority makes its own case. Nutri-Score grades overall nutritional quality from A to E and is voluntary in Spain and other European countries. AESAN points out that it lets you compare products in the same category, such as different breakfast cereals^[6]. With warning seals, two products that carry the same seals look the same on the front of the pack. Warning seals are mandatory in Mexico. NOM-051 describes them as a system that shows excess energy and critical nutrients in a truthful, direct, clear, simple and visible way^[8]. Neither measures processing or satiety.

How do I pick a protein bar?

Read it per calorie like any other label: a bar with 20 g of protein and 200 calories gives 10 g per 100 kcal, double the EU’s mark for “high protein” (see above)^[5]. On a US label, “high in” or “excellent source of” protein means at least 20% of the Daily Value per reference amount (the FDA’s standard serving for that food type), and “good source” 10% to 19%^[18]. The protein %DV is optional, but a bar that makes a protein claim must show it, adjusted for protein quality^[19]. Sugar alcohols such as maltitol only have to be listed when the bar makes a claim about sugars or sugar alcohols^[19], and the FDA requires the warning “Excess consumption may have a laxative effect” on foods that could add up to 50 g of sorbitol a day^[20]. For your daily target, see protein and muscle on GLP-1.