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Dairy

Low-fat kefir

Per 100 g (3.5 oz), kefir provides 3.8 g of protein and 43 kcal, a very low energy density.

USDA description: Kefir, low-fat, plain

  • Easy to digest
  • Low energy density
  • Hydrating

Estimated satietyHow it is calculated

Starting point+1
Very low energy density: 43 kcal/100 g+2
Protein: 8.8 g/100 kcal+2
Fiber: 0.0 g/100 kcal0
Liquid, less filling than a solid; 4.6 g of sugars, under 8−1

Our own estimate from the values per 100 g: useful for comparing foods with each other, not a measurement in people. Holt index (1995): this food was not measured.

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Sources
7 primary
Data
USDA FDC 170904

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Nutrition facts

Calories
86 kcal per serving
43 kcal per 100 g (3.5 oz)
Protein
7.6 g per serving
3.8 g per 100 g (3.5 oz)
Carbohydrates
9.5 g per serving
4.8 g per 100 g (3.5 oz)
of which sugars
9.2 g per serving
4.6 g per 100 g (3.5 oz)
Fiber
0 g per serving
0 g per 100 g (3.5 oz)
Fat
2 g per serving
1 g per 100 g (3.5 oz)
of which saturated
1.3 g per serving
0.7 g per 100 g (3.5 oz)
Water
179.4 g per serving
89.7 g per 100 g (3.5 oz)

Source: USDA FoodData Central: Kefir, lowfat, plain, LIFEWAY (FDC ID 170904), accessed September 23, 2026.

A typical 200 g (7 oz) serving provides about 86 kcal, 7.6 g of protein, and 0 g of fiber.

The typical serving (200 g (7 oz)) is a common amount used for the math, not a recommendation. Ounces and cups are rounded US equivalents; the values come from the database entry cited in the sources.

What it is and how to eat it

Kefir is milk fermented with kefir grains or with cultures that combine bacteria and yeasts, which gives it a sour taste and sometimes a slight fizz. It is thinner than yogurt and you drink it. Fermentation uses up part of the lactose: the kefir on this page has 3.7 g per 100 g, versus 5.05 g in whole milk according to USDA.

A 200 ml (6.8 fl oz) glass provides 7.6 g of protein and 86 kcal. It is liquid, cold and mild, and can be sipped when solid food is hard to face. The 2025 nutrition advisory on GLP-1 therapy suggests small, frequent meals when appetite is low, and a small glass of kefir fits that idea.

What the evidence says

The European Union has not authorized any health claim for probiotics, kefir included: in its official register the claims that were assessed are listed as non-authorized, and the word "probiotic" on a label is itself treated as a health claim. The only authorized claim about live cultures covers the two classic yogurt cultures and lactose digestion, not the microorganisms typical of kefir. A 2023 systematic review of 16 trials in Nutrition Reviews found possible benefits against tooth-decay bacteria, in Helicobacter pylori treatment and, with very limited evidence, for cholesterol and blood pressure, but 12 of the 16 trials had a high risk of bias. Its authors conclude that high-quality trials are needed before kefir can be recommended to treat any condition.

The sources for this section are listed under "Sources" at the end of the page.

Recipes with this food

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Satiety

The 1 to 5 score is our own estimate: it starts at 1 point, adds points for low energy density, for protein and fiber per 100 kcal, and for the water in solid foods, and subtracts points for drinks with calories. It is useful for comparing foods with each other; it is not a measurement in people.

What to keep in mind on a GLP-1 medication

Easy to digest
It is a soft or low-fat food that many people tolerate well when they feel nauseous or get full quickly. This is an editorial judgment based on common patient guidance, not a measurement: everyone tolerates foods differently.
Low energy density
It has 100 kcal or less per 100 g: plenty of volume for few calories, which helps you feel full. On a GLP-1 medication, which already reduces your appetite, make sure these foods do not push protein foods off your plate.
Hydrating
It has 85 g of water or more per 100 g, so it contributes to hydration. That helps because with a smaller appetite people also tend to eat and drink less, and not drinking enough can make constipation worse.

Frequently asked questions about kefir

How many grams of protein are in a small glass of kefir?

A small glass of kefir, our reference serving of 200 g (7 oz), has about 7.6 g of protein. 100 g (3.5 oz) of kefir has 3.8 g of protein. That is 8.8 g of protein per 100 kcal.

How many kcal are in a small glass of kefir?

A small glass of kefir, our reference serving of 200 g (7 oz), has about 86 kcal. 100 g (3.5 oz) of kefir has 43 kcal. That is a very low energy density.

Does kefir keep you full?

Yes, fairly filling for the calories it provides: our estimated satiety score is 4 out of 5. Calculation: 1 (base) + 2 (very low energy density: 43 kcal/100 g) + 2 (protein: 8.8 g/100 kcal) + 0 (fiber: 0.0 g/100 kcal) − 1 (liquid, less filling than a solid; 4.6 g of sugars, under 8) = 4. It is an estimate based on its composition, not a measurement in people.

What should I know about kefir if I take Ozempic, Wegovy, Mounjaro, or Zepbound and feel nauseous?

Based on our tags, this is what matters about kefir on a GLP-1 medication. “Easy to digest”: a soft or low-fat food that many people tolerate well when they feel nauseous or get full quickly. “Low energy density”: plenty of volume for few calories; make sure it does not push protein foods off your plate. “Hydrating”: a lot of water, which contributes to hydration when you eat and drink less. These are general guidelines, not medical advice: everyone tolerates foods differently.

What is a typical serving of kefir?

We use 200 g (7 oz) as a typical serving, roughly a small glass of kefir. That amount provides about 86 kcal, 7.6 g of protein, and 0 g of fiber. It is a reference for calculations, not a recommendation of how much to eat.

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Sources

Sources for the data on this page, with the access date.

  1. Official databaseU.S. Department of Agriculture, Agricultural Research Service.USDA FoodData Central: Kefir, lowfat, plain, LIFEWAY (FDC ID 170904).accessed .
  2. RegulatorEuropean Commission.EU Register of nutrition and health claims made on foods.accessed .
  3. RegulatorFood Safety Authority of Ireland (FSAI).Probiotic health claims.accessed .
  4. RegulatorOfficial Journal of the European Union (EUR-Lex).Commission Regulation (EU) No 432/2012 establishing a list of permitted health claims made on foods.accessed .
  5. Meta-analysisNutrition Reviews (Oxford University Press).Kairey L, et al. The effects of kefir consumption on human health: a systematic review of randomized controlled trials. Nutr Rev. 2023;81(3):267-286. doi:10.1093/nutrit/nuac054.accessed .
  6. Official databaseU.S. Department of Agriculture, Agricultural Research Service.USDA FoodData Central: Milk, whole, 3.25% milkfat, with added vitamin D (FDC ID 171265).accessed .
  7. Clinical guidelineObesity (Wiley).Mozaffarian D, et al. Nutritional priorities to support GLP-1 therapy for obesity: A joint Advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association, and The Obesity Society. Obesity. 2025;33(8):1475-1503. doi:10.1002/oby.24336.accessed .