How to read a nutrition label
Updated: September 13, 2026
You're standing there turning a package over in your hands, staring at a chart with 15 rows of numbers, and you end up putting it back in the cart without understanding a thing. We've all been there. But knowing how to read a nutrition label is probably the single most useful skill you can pick up to level up your nutrition game—way more useful than memorizing the macros of a sweet potato. Here's how to decode it without a headache.
Why the nutrition label changes everything
The marketing on the front of the package tells a story ("high in fiber," "no added sugar," "good source of protein"). The label on the back tells the truth. It's the only part of the packaging that's actually regulated and can't lie to you. If you really want to know what you're eating, that's where the answers are—not on the logo.
In practical terms, this lets you compare two similar products in 10 seconds, spot marketing tricks, and adjust your choices based on your goal (losing fat, building muscle, or just eating better without overthinking it all day).
Serving size: trap number 1
Before you even look at the numbers, check the basis they're calculated on. Most labels show values per 100g, which is handy for comparing products. But some brands, especially with cereal or drinks, also show a "per serving" column—and that serving size is often ridiculously small compared to what you actually eat.
- A bag of chips advertising "110 calories per serving" when the serving is 25g out of a 150g bag
- A "diet" soda can with a 200ml serving listed, even though the can itself is 330ml
- Cereal with an official serving size (30g) that doesn't even fill a third of a bowl
Simple habit to build: always check the per 100g column to compare products, then do the math based on the actual amount you're going to eat.
Calories: the number that sets the tone
Energy value is usually shown in both calories and kilojoules (ignore the kilojoules—they're basically just there for show). This is your starting point, but never the only thing to look at. A product with 400 calories per 100g could be a fast-sugar bomb or a solid base of protein and healthy fats—the difference shows up in the lines below.
With Kaizmax, your program calculates your precise calorie needs using the Mifflin-St Jeor formula, adjusted to your goal and your actual progress. That gives you a clear framework to know whether a product "fits" into your day, instead of just guessing and feeling guilty about it.
Macronutrients: the real heart of the label
Carbs and the sugar trap
The "carbohydrates" line includes everything: starch, fiber, and sugar. The "of which sugars" sub-line is the one to watch closely. Anything above 10g of sugar per 100g means you're dealing with a clearly sweetened product, even if it's marketed as "healthy" (looking at you, cereal bars and fruit yogurts).
- Under 5g of sugar/100g: low
- Between 5 and 15g/100g: moderate
- Over 15g/100g: high, enjoy in moderation
Protein: your muscle-building ally
If your goal is building muscle or just staying full longer, aim for products with at least 15 to 20g of protein per 100g to count them as a good source (meat, fish, eggs, legumes, some dairy). Under 5g/100g, it's not a real protein source, no matter what the packaging claims.
Fat and the saturated fat question
Not all fats are created equal. Check the "of which saturates" sub-line: that's the one that matters for heart health. Under 5g/100g is fine, but above 10g/100g you're looking at a product to limit (deli meats, pastries, certain cheeses).
Salt: the ingredient everyone forgets about
Salt (usually listed as "salt" but sometimes still as "sodium"—multiply sodium by 2.5 to get the salt equivalent) is one of the most overlooked factors in tracking your diet. The recommended intake is around 5g of salt per day for an adult, and some processed meals alone contain more than 2g per serving. Ready meals, deli meats, packaged bread, and sauces are the usual suspects.
Fiber: the number that never gets enough attention
Fiber isn't always listed, but when it is, it's a solid quality indicator. More than 3g of fiber per 100g is a good sign: it slows down sugar absorption, boosts satiety, and helps digestion. Whole grains, legumes, and vegetables are your best friends here.
The ingredient list: the real ultra-processed detector
The nutrition chart gives you the numbers, but the ingredient list gives you the context. Two simple rules:
- Ingredients are listed in descending order by quantity—the first one on the list is what the product contains the most of
- The longer the list and the more unfamiliar names it has (emulsifiers, flavor enhancers, coloring agents), the more processed the product is
Good rule of thumb: if the list has fewer than 5 ingredients you'd recognize from your own kitchen, that's a good sign.
How to put this into practice without losing your mind
You don't need to spend 20 minutes dissecting every single label at the supermarket. Here's the quick 4-step method:
- Start with calories per 100g to get a general sense of the product
- Check the protein-to-sugar ratio: the more it leans toward protein, the better, generally speaking
- Keep an eye on saturated fat and salt if it's something you eat regularly
- Take a quick glance at the ingredient list if the product is processed
With practice, this becomes a 15-second reflex right there in the aisle. And if you want to take it further without doing the math yourself, Kaizmax automatically adjusts your macros based on what you're actually eating and recalculates your program as you progress—so you never have to crunch these numbers alone in the cereal aisle again.
This article is informational and not a substitute for medical advice. In case of a health condition, pregnancy or doubt, consult a healthcare professional.
Want to go further? Browse all the Kaizmax guides. And for your tailored diet + training plan: join the Kaizmax waitlist — a short questionnaire, ready in 2 minutes.