Dairy

Yes, especially concentrated forms. Greek yogurt provides around 9–10 g of protein per 100 g, cottage cheese about 11–12 g, and hard cheeses like Parmesan up to 35 g per 100 g. Dairy protein is roughly 80 percent casein and 20 percent whey, both complete proteins containing all essential amino acids, including a high share of leucine.

Aged hard cheeses such as Parmesan, cheddar, Gruyère and Swiss contain less than 1 g of lactose per 100 g because most of it is removed with the whey and broken down during ageing. Butter and ghee are also very low, and traditionally fermented yogurt and kefir have reduced lactose due to bacterial activity. Fresh milk, by contrast, contains about 4.5–5 g of lactose per 100 ml.

The main difference is fat and energy content. Whole milk has about 3.5 g fat and 60–65 kcal per 100 ml, while skim milk has under 0.5 g fat and around 35 kcal, with nearly identical protein and lactose. Fat-soluble vitamins A and D are naturally higher in full-fat versions, though many low-fat dairy products are fortified to compensate.

Full-fat, low-lactose dairy fits keto well. Butter, hard cheeses, heavy cream and full-fat sour cream contain under 3 g of carbohydrates per 100 g. Milk and plain yogurt are higher in lactose, around 4–5 g of carbs per 100 g, so portions are usually limited. Flavoured and sweetened yogurts, ice cream and condensed milk are typically too high in sugar for a low-carb pattern.