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Is Seaweed Keto-Friendly? (Best Types Ranked)

On the ketogenic diet the goal is to keep your carbohydrate intake low enough. What about seaweed, is it keto-friendly?

Seaweed is a category of different plants that grow in the sea. You can eat some of these on their own, mixed in a salad, or as an ingredient in a variety of recipes.

The first thing to note is that these different plants also contain different amounts of carbohydrates.

The net amount of carbs, which comes down to total carbs minus carbs from fiber, in one example seaweed called agar is around 6.3 grams per 100 grams.

While it depends on the rest of your diet and personal diet, this is a good chunk of your daily carb intake. Agar seaweed in that amount is not very keto-friendly.

On the other hand, a popular seaweed called spirulina only contains about 2.4 grams of net carbs per 100 grams. You should be able to fit that amount into a keto diet.

This article also looks at the amounts of carbs in a few other types of seaweed and what happens to the nutrient concentration if you dry seaweed.

When is a food keto-friendly

The goal of the ketogenic diet is to put your body into ketosis, a state where it starts mainly burning fat as a fuel (1). This comes down to more or less getting 55%-60% of your macronutrients from fat, 30%-35% from protein, and 5%-10% from carbohydrates.

For most people this comes down to eating around 20g – 50g of carbohydrates a day.

In reality, this number is different depending on a lot of factors. For example, people who exercise a lot may be able to consume more carbohydrates before getting kicked out of ketosis.

That being said that daily amount can be a good general guideline.

It is also common to exclude fiber from this amount since it doesn’t get absorbed into your body the same way as regular carbohydrates.

Carbs in agar seaweed

100 grams of raw agar seaweed contains the following amounts of carbs (2):

  • Total carbs: 6.8 grams
  • Of which fiber: 0.5 grams
  • Net carbs: 6.3 grams

This food is not the highest in net carbohydrates, it is very possible that the 6.3 grams of net carbs in 100 grams of raw agar seaweed are enough to kick you out of ketosis.

One ounce of raw agar seaweed is about 28 grams and contains the following amounts of carbs:

  • Total carbs: 1.9 grams
  • Of which fiber: 0.1 grams
  • Net carbs: 1.8 grams

The number of net carbs in 1 ounce of raw agar seaweed, 1.8 grams, is a lot easier to fit into a keto diet.

Whether or not agar seaweed is keto for you ultimately depends on what portion you have in mind, your individual situation, and the rest of your diet.

Carbs in dried agar seaweed

Seaweed is often used in its dry form too. By taking out the water, the nutrition contents per 100 grams change a lot.

As an example, 100 grams of dried agar seaweed contains 80.9 grams of total carbs which includes 7.7 grams of fiber (3). That means it contains 73.2 grams of net carbs.

You will obviously eat less dried seaweed than raw seaweed but this is something you do want to keep in mind.

Carbs in different types of seaweed

Seaweed is a broad category of different plants. In turn, these plants typically vary in the nutrients they contain, including carbohydrates.

That means some types of seaweed will be better than others for staying in ketosis. These are the net carb values per 100 grams (4, 5, 2, 6, 7, 8):

  • Spirulina seaweed: 2.4 grams of net carbs
  • Laver seaweed: 4.8 grams of net carbs
  • Agar seaweed: 6.3 grams of net carbs
  • Kelp seaweed: 8.3 grams of net carbs
  • Wakame seaweed: 8.6 grams of net carbs
  • Irish moss seaweed: 11 grams of net carbs

As you can see, agar is a decent example of what you can expect in terms of carbohydrates in seaweed.

Other nutrients in agar seaweed

Other nutrients like fat, protein, vitamins, and minerals also still matter on the ketogenic diet.

100 grams of raw agar seaweed contain the following nutrients (2):

  • Calories: 26
  • Protein: 0.5 grams
  • Carbs: 6.8 grams
  • Part of the carbs that is fiber: 0.5 grams
  • Fat: 0 grams
  • Folate: 21% of the DV (Daily Value)
  • Manganese: 19% of the DV
  • Magnesium: 17% of the DV
  • Iron: 10% of the DV
  • Potassium: 6% of the DV

And some other vitamins and minerals in smaller amounts.

While agar seaweed is somewhat higher in net carbs, it does contain a few valuable nutrients in nice amounts. You could consider eating this type of seaweed and others in limited amounts on a ketogenic diet.

How to avoid eating too much seaweed

To be able to fit seaweed into your keto diet, you may have to exercise some portion control. Snacking on a big bag of nori (a type of dried seaweed) and hoping that you don’t eat too much is not the ideal way to do this.

You can avoid eating too much seaweed with some of the following tips:

  • Plan ahead, how many grams of seaweed will you eat?
  • Put the planned amount in a bowl and leave the rest of the seaweed out of sight
  • Don’t eat during other activities like watching TV
  • Consider not preparing or buying seaweed if you crave it too much

If you notice you get out of ketosis you may need to reduce the amount of seaweed you eat.

What is your goal with keto?

Even a small portion of seaweed added to certain daily diets could potentially put you just over the net carbs border, out of ketosis. Depending on the goal you have with keto this may or may not be a problem.

If your goal is to stay strictly in ketosis 24/7 you want to be careful about your carbohydrate intake.

If your goal is to lose weight and become healthier, seaweed can be a good food option even if it potentially puts you at a carbohydrate level slightly above your ketosis level.


Matt Claes

Matt Claes founded Weight Loss Made Practical to help people get in shape and stay there after losing 37 pounds and learning the best of the best about weight loss, health, and longevity for over 4 years. Over these years he has become an expert in nutrition, exercise, and other physical health aspects.