Is Seaweed Keto-Friendly? (Best Types Ranked)

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Seaweed contains a nice amount of micronutrients but that does not mean it is low-carb. Find out whether this food is keto-friendly and what the best options are.

The first thing to note is that there are a variety of seaweeds. Different types can contain different amounts of carbs.

A somewhat average example is agar seaweed. 100 grams of this food contains around 6.3 grams of net carbohydrates (total carbs minus fiber).

Since this is a good amount of carbs, agar seaweed is generally not that keto-friendly.

You could still be able to eat certain amounts while staying in ketosis. However, even then, it may not be worth it to spend so many of your daily carbs on such a small amount of food.

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 nutrition facts per 100 grams when you dry seaweed.

Carbs in agar seaweed

When figuring out whether a food option like agar seaweed is keto-friendly or not, you definitely want to look at the amounts of carbohydrates in it.

100 grams of raw agar seaweed contain the following amounts of carbs (1):

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

There are definitely foods that are higher in carbohydrates than this too.

However, it is fair to say that raw agar seaweed is somewhat higher in carbs and in turn, generally not that keto-friendly.

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

As you can expect, consuming smaller amounts of agar seaweed will also mean that you eat fewer carbohydrates. In turn, it becomes somewhat easier to fit this food into your ketogenic diet.

At the same time, you may still not want to consume so many of your daily carbs in such a small amount of food.

How many carbs there are in dried agar seaweed

Seaweed is often available in its dried form too. Taking out the water does change the nutrition details per 100 grams 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 (2).

This comes down to 73.2 grams of net carbs which is a lot more and definitely not that keto-friendly.

Not many people will eat this amount of dried seaweed but you definitely want to remember this difference.

Carbs in different types of seaweed

Seaweed is not just one specific plant. There are a variety of different seaweed types with varying amounts of nutrients, including different amounts of 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 of a few different types (3, 4, 1, 5, 6, 7):

  • 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 about what you can expect in terms of the amounts of carbohydrates in seaweed.

Other nutrition facts about agar seaweed

How many carbohydrates seaweed contains is important on a keto diet but other nutrients like fats, proteins, vitamins, and minerals still matter.

These influence how good your general health will be and even whether you will stay in ketosis.

100 grams of raw agar seaweed contain the following nutrients (1):

  • 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.

The amounts of vitamins and minerals in agar seaweed are decent and welcome but there are more nutritious foods that are lower in carbs too.

So you can still consider small amounts of agar seaweed but you don’t have to force yourself. You can get nutrients from many other foods too.

Why seaweed is sometimes allowed on keto

As mentioned, seaweed is often not that keto-friendly. However, that does not mean you will always get kicked out of ketosis if you eat this food.

Ketogenic diets are ways of eating where you get and stay in ketosis. This is a state where you mainly burn fat as fuel (8).

To get into ketosis you have to keep your carbohydrate intake low enough. Exactly how low depends on details like your body weight, muscle mass, activity levels, etc.

This keto diet fact does make things a bit more complicated but there are still some general guidelines. These are not perfect but do help you understand how much seaweed could kick you out of ketosis.

A typical recommendation for people who want to stay in ketosis is to get 55%-60% of their macronutrients from fat, 30%-35% from protein, and 5%-10% from carbohydrates.

If you do the calculations, you will likely conclude that you can eat around 20 to 50 grams of carbohydrates a day on a ketogenic diet.

Something to note is that you don’t include fiber in these amounts. While fiber is a category of carbohydrates, your body processes it in a different way.

With this, you can start to estimate how many grams of what types of seaweed you could consider eating.

How to avoid eating too much seaweed on keto

So you likely have to keep an eye on your portion sizes if you want to eat seaweed on a ketogenic diet.

Snacking on a big bag of nori (a type of dried seaweed) and hoping that you don’t eat too many carbohydrates will typically not be a good strategy.

Some of the following tips can help you avoid overeating seaweed:

  • Estimate in advance how many grams of seaweed you can/want to eat
  • Weigh out this many grams and put the rest of the seaweed somewhere else
  • Don’t eat seaweed mindlessly while doing other activities like watching a movie

Even with these tips, you could get kicked out of ketosis when eating seaweed. This would be a sign that your carbohydrate intake estimations are too optimistic.

Why do you follow a keto diet?

By now it should be clear that seaweed definitely has the potential to kick you out of ketosis. How much of a problem this is depends on why you follow a keto diet.

There are people who need/want to stay in ketosis every minute of the day. These individuals want to be careful about how many carbs they eat and potentially want to stay away from seaweed.

On the flip side, even if seaweed would kick you out of ketosis, it could help you lose weight and get healthier. Ketogenic diets have their benefits but you can often achieve the health goals above without them.

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

Related posts:

Is seaweed high in carbohydrates?

Agar seaweed contains about 6.8 grams of carbs (including 0.5 grams of fiber). That means agar seaweed is not that high in carbohydrates but at the same time, there are many foods lower in carbs too.

Is wakame keto?

Raw wakame seaweed contains around 8.6 grams of net carbs per 100 grams. You could be able to fit in small portions but wakame is generally not that keto-friendly.

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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.