Is skyr actually yogurt?

Technically no — skyr is classified as a fresh, soft cheese because of how it's cultured (traditionally with heirloom Icelandic strains, sometimes a touch of rennet) and heavily strained. In practice it's sold in the yogurt aisle, eaten like yogurt, and contains live and active cultures just like yogurt, so the distinction matters more to food scientists than to your breakfast.

Can I eat skyr on a keto diet?

Yes, in measured portions. Plain skyr has about 4 g of net carbs per 100 g (roughly 6 g in a 150 g cup), which fits a 20–50 g net-carb day. Since traditional skyr is nonfat, many keto eaters prefer plain whole-milk Greek yogurt instead — same carbs, but about 5 g of fat per 100 g, which suits keto macros and keeps you full longer. Skip flavored versions of either; they can add 8–14 g of sugar per cup.

Which has more sugar, skyr or Greek yogurt?

Plain versions are essentially tied at 3–4 g of naturally occurring milk sugar (lactose) per 100 g — less than unstrained regular yogurt, because straining drains lactose off with the whey. The big sugar differences come from flavoring, not the base product: a vanilla or fruit version of either can carry two to three times the carbs of plain.

Is skyr or Greek yogurt better for weight loss?

Both are excellent because protein is filling and they're low in calories for their volume. Nonfat skyr is the most protein-dense option — about 11 g protein per 100 g at only ~63 calories, with roughly 70% of calories from protein. If you do better with fewer, more satisfying meals, 2% or whole-milk Greek adds fat that improves satiety at a modest calorie cost. The plain version of either beats a flavored version of both.

Skyr vs Greek Yogurt: Protein, Carbs & Which to Pick

Skyr has ~11g protein per 100g vs ~10g for Greek yogurt; both have ~4g carbs. Skyr is leaner, but plain whole-milk Greek usually fits keto better.

Skyr and Greek yogurt are nutritional near-twins: both are strained, both pack roughly 9–11 g of protein per 100 g, and both land around 3.5–4 g of carbs per 100 g in their plain versions. Skyr edges out Greek on protein and is traditionally fat-free; Greek yogurt is easier to find in full-fat form, which makes it the more practical pick for keto. For everyone else, it's close enough that taste and price can decide.

Quick comparison table

Typical USDA values for plain, unsweetened versions, per 100 g (about 7 tablespoons — a standard single-serve cup is 150–170 g, so multiply by 1.5–1.7 for a cup):

Per 100 g (plain)	Calories	Carbs	Net carbs	Protein	Fat
Skyr, nonfat (traditional)	63	4.0 g	4.0 g	11 g	0.2 g
Greek yogurt, nonfat	59	3.6 g	3.6 g	10.2 g	0.4 g
Greek yogurt, 2% (low-fat)	73	3.9 g	3.9 g	9.9 g	1.9 g
Greek yogurt, whole milk	97	3.9 g	3.9 g	9.0 g	5.0 g
Regular yogurt, whole milk (for reference)	61	4.7 g	4.7 g	3.5 g	3.3 g

Since dairy has no fiber, net carbs equal total carbs here. The carbs are almost entirely lactose, the milk's natural sugar — straining drains much of it off with the whey, which is why both products sit well below the 4.7 g per 100 g of regular yogurt despite being far more concentrated in protein.

What actually makes skyr and Greek yogurt different?

Both start as milk fermented with live bacterial cultures, then get strained to remove whey. The differences are in the details.

Skyr is an Icelandic product that's technically classified as a fresh cheese, though it's eaten like yogurt. It's traditionally made from skim milk, cultured with heirloom Icelandic strains (plus the standard Streptococcus thermophilus and Lactobacillus species), sometimes with a small amount of rennet, and strained heavily — it takes roughly 4 cups of milk to make 1 cup of skyr. That aggressive straining is why it's the thickest thing in the yogurt aisle and why its protein is a touch higher.

Greek yogurt is regular yogurt strained to remove whey — typically about 3 cups of milk per cup of finished yogurt. Unlike skyr, it's made across the fat spectrum: nonfat (0%), low-fat (2%), and whole milk (4–5%), all widely available in American grocery stores.

Two practical consequences:

Live cultures: both deliver live and active cultures if the label says so (look for the "Live & Active Cultures" seal or a "contains live cultures" note). Neither has a categorical probiotic advantage — it depends on the brand and strains, not on whether it's called skyr or Greek.
Lactose: straining removes a good share of the lactose along with the whey, so both are gentler than regular yogurt for people who are mildly lactose sensitive. Fully lactose-intolerant folks still need a lactose-free option.

Which has more protein and fewer carbs?

Protein: skyr wins, but narrowly. Plain nonfat skyr runs about 11 g of protein per 100 g versus about 10 g for nonfat Greek — roughly a 10% edge. In real-serving terms, a 150 g cup of skyr (Siggi's plain nonfat, for example) gives you about 16 g of protein for ~100 calories, while the same size cup of nonfat Greek gives about 15 g. A larger 170 g cup of nonfat Greek (a standard Fage or Chobani single-serve) delivers about 17 g. So the winner can flip depending on cup size — check the actual label, not the category.

Carbs: effectively a tie. Plain versions of both land at 3.5–4.5 g of carbs per 100 g, or about 5–7 g per single-serve cup. Brand-to-brand variation (5 g vs 6 g per cup) is bigger than any skyr-vs-Greek difference.

The real carb trap is flavoring, not the base product. A vanilla or fruit-on-the-bottom version of either can carry 8–14 g of added sugar per cup, tripling the carb count. A flavored skyr is not a low-sugar food just because skyr sounds healthy; the same goes for "light" Greek yogurts sweetened with fruit purée. Buy plain and add your own berries or cinnamon — you control the carbs and usually save money.

Fat is where they genuinely diverge. Traditional skyr is nonfat by design (0–0.5 g per 100 g), though whole-milk skyr now exists from brands like Icelandic Provisions. Greek yogurt's whole-milk version carries about 5 g of fat per 100 g — call it 8–9 g per cup — which changes the calorie math (97 vs 63 calories per 100 g) and, importantly, the satiety and keto math below.

Is skyr or Greek yogurt better for keto and low-carb diets?

Both fit. On a keto budget of 20–50 g net carbs per day, a 150 g serving of plain skyr or plain Greek yogurt costs you about 5–7 g of net carbs — very affordable for the protein, calcium (150–200 mg per serving), and live cultures you get in return. There's no fiber or sugar alcohol in plain versions, so the net-carb calculation (total carbs minus fiber minus sugar alcohols) is just the total-carb number on the label.

That said, plain whole-milk Greek yogurt is usually the better keto pick, for two reasons:

Macro fit. Keto runs on fat. Whole-milk Greek delivers roughly 45% of its calories from fat, while nonfat skyr delivers essentially none — it's nearly pure protein, which is great for a high-protein diet but leaves a keto eater topping it up with nuts, seeds, or a spoon of nut butter anyway.
Satiety per serving. At 97 calories per 100 g with fat on board, full-fat Greek holds you longer between meals than a 63-calorie nonfat skyr of the same weight, for nearly identical carbs.

Flip the goal and the answer flips too: if you're doing general low-carb with a calorie target, or prioritizing protein for muscle retention while cutting, nonfat skyr is arguably the single most protein-dense item in the dairy case — about 70% of its calories come from protein. It's also a strong base for savory uses (think tzatziki-style sauces or a sour cream stand-in) where you don't want extra richness.

One label note for carb counters: a few brands round differently or add milk protein concentrate and pectin, which barely move carbs, but fruit "compote" corners and honey packets absolutely do. Log what's actually in the cup.

How do taste and texture compare?

Skyr is thicker and denser — closer to soft cheese than yogurt, which makes sense given its classification. It holds a spoon upright, resists getting watery, and has a milder, less tangy flavor than Greek. If you find Greek yogurt too sour, skyr is worth a try.

Greek yogurt is creamy with a pronounced tang, especially in nonfat versions where there's no fat to soften the acidity. Whole-milk Greek is the most indulgent-tasting of the bunch — rich enough to pass for a dessert base with a few raspberries.

In the kitchen they're mostly interchangeable: both work in smoothies, dips, marinades, and as sour cream or mayo substitutes. Skyr's density makes it slightly better for thick dips and parfaits; whole-milk Greek behaves better in warm sauces because the fat helps it resist curdling (nonfat versions of either will split if you boil them).

Price is the quiet tiebreaker: skyr typically costs more per ounce in US stores, and store-brand plain Greek is often the best protein-per-dollar in the aisle.

The bottom line

There's no wrong answer here — plain skyr and plain Greek yogurt are two of the best protein-to-carb deals in any grocery store. Pick nonfat skyr if you want maximum protein density (~11 g per 100 g) with minimal calories, a milder flavor, and the thickest texture. Pick plain whole-milk Greek yogurt if you're eating keto or low-carb and want the fat for satiety and macro balance at the same ~4 g of carbs per 100 g. Whichever you choose, buy it plain: the skyr-vs-Greek difference is a rounding error compared with the 8–14 g of added sugar hiding in flavored cups.