Saciedad

Vegetables and starchy roots

Onion

Onions are 89% water, so 100 g (3.5 oz) brings only 40 kcal and 1.7 g of fiber.

Last reviewed: By USDA description: Onion, raw

  • 40 kcalCalories per 100 g
  • 1.1 gProtein per 100 g
  • 1.7 gFiber per 100 g
  • Estimated satiety: 5 out of 5

Nutrition facts

A typical 50 g (2 oz, about 1/4 cup) serving provides about 20 kcal, 0.6 g of protein, and 0.9 g of fiber.

Values for onion per 100 g (3.5 oz) and per typical serving of 50 g (2 oz, about 1/4 cup).
NutrientPer 100 g (3.5 oz)Per serving (50 g (2 oz))
Calories40 kcal20 kcal
Protein1.1 g0.6 g
Carbohydrates9.3 g4.7 g
of which sugars4.2 g2.1 g
Fiber1.7 g0.9 g
Fat0.1 g0.1 g
of which saturated0 g0 g
Water89.1 g44.6 g

The typical serving 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.

Satiety

Very low energy density; a lot of fiber per calorie; high water content.

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

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.
May cause bloating
Beans and other legumes, cruciferous vegetables, onions, and carbonated drinks cause gas in some people. Because GLP-1 medications slow down stomach emptying, that bloated feeling can be more noticeable. This is an editorial judgment: many people tolerate these foods well in moderate servings.

Frequently asked questions about onions

How many grams of protein are in a 50 g (2 oz) serving of onions?

100 g (3.5 oz) of onions has 1.1 g of protein. A typical 50 g (2 oz) serving has about 0.6 g of protein. That is 2.8 g of protein per 100 kcal.

How many kcal are in a 50 g (2 oz) serving of onions?

100 g (3.5 oz) of onions has 40 kcal. A typical 50 g (2 oz) serving has about 20 kcal. That is a very low energy density.

How much fiber is in a 50 g (2 oz) serving of onions?

100 g (3.5 oz) of onions has 1.7 g of fiber. A typical 50 g (2 oz) serving has about 0.9 g of fiber.

Do onions keep you full?

Yes, very filling for the calories they provide: our estimated satiety score is 5 out of 5. It is based on: very low energy density; a lot of fiber per calorie; high water content. It is an estimate based on its composition, not a measurement in people.

How do onions fit into eating on Ozempic, Wegovy, Mounjaro, or Zepbound?

Based on our tags, this is what matters about onions on a GLP-1 medication. “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. “May cause bloating”: it can cause gas or bloating in some people, and on a GLP-1 medication that feeling can be more noticeable. These are general guidelines, not medical advice: everyone tolerates foods differently.

What is a typical serving of onions?

We use 50 g (2 oz) as a typical serving, about 1/4 cup. That amount provides about 20 kcal, 0.6 g of protein, and 0.9 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. USDA FoodData Central: Onions, raw (FDC ID 170000). U.S. Department of Agriculture, Agricultural Research Service. accessed .