Mozzarella cheese is very low in carbohydrates, with roughly 1 gram or less per one-ounce serving. That makes it a reliable option for keto, low-carb, and diabetic-friendly diets. The exact count varies depending on the type of mozzarella and how it’s packaged, but even in a worst-case scenario, you’re looking at minimal carbs.
Why Mozzarella Is So Low in Carbs
The only significant carbohydrate in cheese is lactose, the natural sugar found in milk. A cup of whole milk contains about 12 grams of lactose, but the cheese-making process strips most of it away. During mozzarella production, bacteria rapidly ferment the lactose in the curd. Within the first five hours of manufacturing, lactose concentration in the curd drops by more than 60%. By the time the curd is stretched in hot water (the step that gives mozzarella its signature pull), the pH has already fallen from 6.6 to 5.2, a sign that most of the sugar has been consumed by the starter cultures.
After that fermentation plus the draining of whey (which carries dissolved lactose away), very little remains. Part-skim, low-moisture mozzarella contains between 0.08 and 0.9 grams of lactose per ounce. That’s essentially a rounding error on a nutrition label, which is why many mozzarella products list 0 grams of carbohydrate per serving. A standard string cheese stick (28 grams), for example, registers 0 grams of total carbohydrate.
Fresh vs. Low-Moisture Mozzarella
Not all mozzarella is identical. The two main types you’ll encounter at the grocery store are fresh mozzarella (the soft, white balls packed in liquid) and low-moisture mozzarella (the firmer block or shredded cheese used on pizza). Fresh mozzarella contains more water, between 52% and 60% moisture, compared to 45% to 52% for the low-moisture version. That higher water content slightly dilutes everything, including the small amount of remaining lactose, so per ounce, both types stay very low in carbs.
Fresh mozzarella nutrition labels typically show about 1 gram of carbohydrate per ounce. Low-moisture mozzarella often rounds down to 0 grams. The difference is negligible for most people, but if you’re strictly tracking every gram on a ketogenic diet, low-moisture mozzarella gives you a tiny edge.
Watch for Pre-Shredded Varieties
The one place mozzarella carbs can creep up is in pre-shredded bags. Manufacturers coat shredded cheese with anti-caking agents to prevent clumping. Common coatings include cellulose, potato starch, corn starch, and rice starch. These are carbohydrate-based powders, and they can add 1 to 2 extra grams of carbohydrate per serving compared to block cheese that you shred yourself.
If minimizing carbs matters to you, check the ingredient list. Block mozzarella or string cheese avoids the issue entirely. If you do buy shredded, look for brands that use cellulose (plant fiber) rather than potato or corn starch, as cellulose contributes less digestible carbohydrate.
How Mozzarella Compares to Other Cheeses
Most aged and semi-firm cheeses are extremely low in carbs, and mozzarella fits right in with the group. Here’s how common cheeses compare per one-ounce serving:
- Parmesan: 0 grams of lactose. The long aging process ferments virtually all of it.
- Cheddar: 0.07 grams of lactose. Another excellent low-carb choice.
- Brie: 0.13 grams of lactose. Soft-ripened cheeses are slightly higher but still negligible.
- Mozzarella (part-skim, low-moisture): 0.08 to 0.9 grams of lactose, depending on the brand and batch.
The pattern is straightforward: harder, more aged cheeses tend to have less lactose because fermentation has had more time to work. Mozzarella is younger and softer than cheddar or parmesan, so it retains a bit more, but the difference is less than a single gram.
Mozzarella on a Keto or Low-Carb Diet
For anyone following a ketogenic diet (typically under 20 to 50 grams of carbs per day), mozzarella is one of the safest foods on your list. You could eat several ounces without making a meaningful dent in your daily carb budget. Cheese in general has a low glycemic index, meaning it releases glucose slowly and doesn’t trigger significant blood sugar spikes. That also makes it a practical snack for people managing diabetes.
Beyond its low carb count, mozzarella brings useful macros to a low-carb plate. A one-ounce serving of part-skim mozzarella provides about 7 grams of protein and 5 grams of fat, making it a decent source of both. Whole-milk mozzarella bumps the fat up to around 6 grams per ounce while keeping protein similar. If you’re aiming for higher fat ratios on keto, whole-milk versions are the better pick.
String cheese and cheese sticks are particularly convenient for low-carb snacking because they come in pre-portioned, single-serving sizes with no anti-caking agents to worry about. Paired with a handful of nuts or some sliced vegetables, they make a quick, carb-conscious snack that doesn’t require any label math.