Why Can I Eat Cheese but Not Drink Milk on Keto?

October 9, 2025 •

3 min read

According to the USDA, a single cup of 1% cow's milk contains 12.7 grams of carbohydrates, primarily from lactose. This high carb count is why you can eat cheese but not drink milk on keto, because the cheesemaking process removes most of the problematic sugar.

Quick Summary

The discrepancy between cheese and milk on the ketogenic diet comes down to their carbohydrate content, which is largely influenced by processing. Cheeses are low-carb due to fermentation, a process that feeds on lactose (milk sugar). In contrast, milk retains its high lactose content, making it unsuitable for a low-carb diet like keto.

Key Points

Lactose is the primary factor: The main reason milk is not keto-friendly is its high lactose (milk sugar) content, whereas cheese is low in carbs because most lactose is removed during processing.
Cheesemaking reduces carbs: The process of separating milk into curds and whey drains away most of the whey, which contains the majority of the milk's lactose.
Aging further reduces lactose: For hard-aged cheeses like parmesan and cheddar, the remaining lactose is consumed by bacteria during the aging process, minimizing the final carb count.
Beware of hidden sugars: Not all dairy is created equal on keto; avoid low-fat or flavored dairy products that often contain added sugars to compensate for lost fat.
Choose high-fat, low-carb options: Dairy products like hard cheeses, heavy cream, and plain Greek yogurt are the best keto choices due to their high fat and low carbohydrate profiles.

The fundamental difference between milk and cheese, which explains why one is keto-friendly and the other is not, is the presence of lactose, a type of milk sugar. While a cup of milk can easily consume a significant portion of a keto dieter's daily carbohydrate allowance, most aged cheeses have minimal to no lactose, and therefore, far fewer carbs.

The Cheesemaking Process: The Keto Secret

The transformation of high-carb milk into low-carb cheese is a fascinating process that makes it compatible with a ketogenic lifestyle.

Step 1: Curdling. The first stage involves adding a coagulant, like rennet or an acid, to milk. This causes the milk to separate into solid curds (proteins and fat) and a watery liquid known as whey.
Step 2: Draining the Whey. The liquid whey contains the majority of the milk's lactose. During this step, the cheesemaker drains off the whey, leaving behind the carb-light curds. The amount of lactose removed depends on the cheese type, with harder cheeses having more whey removed than softer varieties.
Step 3: Fermentation and Aging. For aged cheeses like cheddar or parmesan, the curds are pressed and aged. During this maturation period, bacteria consume the remaining trace amounts of lactose, converting it into lactic acid and further lowering the carbohydrate count. This is why aged cheeses are often the most keto-friendly option.

Milk vs. Cheese: A Nutritional Comparison for Keto

To better understand the differences, a direct comparison of a standard cup of milk versus a typical serving of hard cheese is useful.


Feature	1 Cup of Cow's Milk (approx.)	1 oz of Aged Hard Cheese (approx.)
Lactose/Carbs	~12-13 grams	<1 gram
Fat	Medium (varies by milk type)	High
Protein	~8 grams	~6 grams
Suitability for Keto	Not suitable in standard quantities	Highly suitable
Impact on Ketosis	Can easily disrupt ketosis	Unlikely to disrupt ketosis in moderation

How to Enjoy Dairy on a Keto Diet

While whole milk is generally off the table for keto, many dairy products are perfectly acceptable. The key is to choose items where the lactose has been removed, reduced, or is present in very small quantities.

Hard Cheeses

Aged, hard cheeses like parmesan, cheddar, Swiss, and provolone are excellent choices due to their minimal lactose content. They are high in fat and can be used to add flavor and satiety to many dishes.

Soft and Fresh Cheeses

Softer cheeses such as mozzarella, brie, and cream cheese are also acceptable, though they contain slightly more lactose than their hard-aged counterparts. Always check the nutrition label, especially for processed cheese products, to avoid hidden sugars.

Heavy Cream and Half-and-Half

These products are high in fat and low in carbohydrates, making them suitable for adding to coffee or sauces in moderate amounts. The low sugar content is due to the process of separating the fat from the liquid milk, leaving the lactose behind.

Full-Fat Greek Yogurt

Plain, full-fat Greek yogurt is a viable option due to its fermentation process, which reduces lactose. However, the carbohydrate content can vary, so it's important to read the label. Avoid all sweetened or fruit-flavored yogurts, as these contain large amounts of sugar.

The Risks of Hidden Sugars and Dairy Digestion

It's important to remain vigilant about hidden carbs in dairy products, even seemingly keto-friendly ones. Many "low-fat" or flavored dairy items replace fat with added sugars to improve taste and texture, which can derail ketosis. Furthermore, while cheese's low lactose content makes it a better choice for keto, some individuals with severe lactose intolerance may still react to trace amounts. It's crucial to listen to your body and adjust dairy intake accordingly.

Conclusion: The Final Verdict on Milk vs. Cheese on Keto

In summary, the reason you can enjoy cheese but not milk on a ketogenic diet boils down to one simple fact: lactose. The cheesemaking process removes the vast majority of this natural milk sugar, resulting in a low-carb, high-fat food that aligns with keto macros. Milk, on the other hand, retains its high lactose content and is too high in carbohydrates for regular consumption. By understanding this fundamental distinction and choosing your dairy products wisely, you can continue to enjoy the rich flavors of cheese while successfully maintaining ketosis.

For more information on the fermentation process, see this guide from cheeseforthought.com.

Frequently Asked Questions

No, skim milk is not recommended on a keto diet. Removing the fat from milk concentrates the lactose, or milk sugar, increasing the carbohydrate ratio and making it unsuitable for a low-carb diet.

Surprisingly, no. Lactose-free milk contains the same number of carbs as regular milk because the lactase enzyme added simply breaks the lactose into simpler sugars (glucose and galactose), which still impact blood sugar and can disrupt ketosis.

Hard, aged cheeses like parmesan, cheddar, and Swiss are the most keto-friendly because the aging process consumes nearly all the lactose, leaving very few carbohydrates.

While these are low-carb, they contain more lactose than hard cheeses because they are less aged. They should be consumed in moderation while keeping track of your daily carb intake to stay in ketosis.

Yes, butter is very keto-friendly. It is made from milk fat and contains only trace amounts of lactose, making it an excellent high-fat, low-carb addition to your diet.

You should avoid regular cow's milk, sweetened condensed milk, and low-fat dairy products with added sugars. Also, be cautious with milk alternatives like oat or rice milk, which can be high in carbs.

Yes, heavy cream and half-and-half are keto-friendly because they consist of the fatty portion of milk, leaving most of the lactose behind. They are great for adding flavor and fat to your keto meals.