Carrageenan, one of the active components in sea moss, may help you lose weight by increasing feelings of fullness, lowering your body fat, and improving your gut microbiota.

Sea moss (Chondrus crispus) is a red algae popular among health enthusiasts due to its purported health benefits, including weight loss.

While research supports the idea that sea moss has multiple benefits, you may still be wondering whether the weight loss claims about it are true.

This article reviews the benefits and downsides of sea moss and explores whether it may help you lose weight.

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Sea moss is a red seaweed, also known as Irish moss.

It commonly grows in the Northern Atlantic coasts of America and Europe, mainly in Canada, Ireland, and Iceland (1).

Sea moss is harvested due to its high carrageenan content — namely lambda-carrageenan. This is a polysaccharide widely used as a thickener and stabilizer in the cosmetic and food industries (2, 3).

It’s also rich in minerals, such as:

  • iodine
  • calcium
  • magnesium
  • iron

These are necessary for numerous body functions, including thyroid function, bone health, building muscle, and transporting oxygen (4, 5, 6, 7).

Also, sea moss is very low in calories. A serving of 2 tablespoons (10 grams) of sea moss contains just 5 calories and 1 gram of carbs (8).

While sea moss is currently touted for its weight loss effects, it is traditionally used as a home remedy to treat sore throats and congestion.


Sea moss is a red seaweed low in calories and high in carrageenan, a polysaccharide used for its thickening and stabilizing properties.

Sea moss has a few properties that may support weight loss.

Research indicates it may help:

May increase feelings of fullness

Carrageenan is one of sea moss’s main bioactive compounds. Due to its gelling ability and the fact that your body can’t digest it, it acts like soluble fiber in your digestive tract (3).

Soluble fiber absorbs water and forms a gel-like substance. This slows digestion by increasing the rate at which food moves through your digestive tract and delaying the rate at which your stomach empties its contents (9).

So, it may leave you feeling fuller for longer, which may help you eat less. In fact, regular soluble fiber intake has been linked to lower body weight (10, 11).

May help reduce body fat

Some research on red seaweed suggests that carrageenan may potentially prevent weight gain.

Animal studies indicate that it may help reduce body fat by (12, 13):

  • lowering dietary fat absorption
  • reducing the creation of fat cells
  • increasing the breakdown of stored fat
  • promoting the “fat-burning” effect of brown fat tissue

Additionally, a 12-week study including 78 adults with obesity determined that supplementing 1,000 milligrams per day of red seaweed extract significantly reduced body weight and total body fat mass, compared with the control group (12).

Still, more human research is needed to validate this effect.

May have a prebiotic effect

Prebiotics are groups of fibers that act as food for your gut’s friendly bacteria — or gut microbiota (14).

Recent studies suggest that the composition of your gut’s microbiota may influence your risk of obesity. The proposed mechanism is that specific types of bacteria in your gut may affect your weight by regulating energy expenditure and storage (13, 15, 16).

That said, prebiotics may help make your gut microbiota healthier. And research on carrageenan shows promising results that it may improve the gut’s composition (12, 13, 14).

Animal studies have shown that it may help increase beneficial bacteria such as Bifidobacterium breve and reduce harmful species such as Clostridium septicum and Streptococcus pneumonia (17, 18).


Sea moss may aid in weight loss due to its carrageenan content, which may increase feelings of fullness, lower body fat, and improve your microbiota profile.

Consuming large amounts of sea moss is not recommended, due to its high iodine content (19, 20).

Excessive iodine intake may have a poisonous effect and lead to: goiter, thyroid cancer, and hyper- or hypothyroidism (4, 21).

It may also cause fever, nausea, vomiting, and diarrhea, as well as a burning sensation in the mouth, throat, and stomach (21, 22).

Additionally, seaweeds such as sea moss may accumulate toxic metals like arsenic, mercury, and lead — a potential health risk (4).

What’s more, evidence suggests that sea moss may have potent anticoagulant or blood-thinning properties. That’s why you should avoid consuming it if you’re taking blood-thinning medication (23).

Due to a lack of research on specific populations, pregnant and breastfeeding people should avoid consuming it.

Finally, there’s no official recommended dosage for sea moss.

However, one study found that taking 0.14 ounces (4 grams) per day doesn’t pose a health risk. Frequent users suggest limiting its intake to 2 tablespoons (10 grams) per day (20).

Sea moss is available in capsule, powdered, dried, and gel form.

Consult with your doctor before adding it to your diet and don’t exceed daily serving suggestions listed on the label.


Large amounts of sea moss may lead to excessive iodine intake, which may have detrimental health effects. Pregnant and breastfeeding people and those taking blood thinners should avoid consuming it. More research is needed in this area.

Sea moss is a red seaweed low in calories but rich in carrageenan. This polysaccharide acts as a soluble fiber, and it’s responsible for sea moss’s potential weight loss effects.

It may aid in weight loss by:

  • promoting feelings of fullness
  • influencing fat metabolism
  • improving your gut microbiota

However, there’s currently no determined safe dosage, and high intakes of sea moss may be detrimental to your health. It may cause iodine toxicity and also interfere with medications, such as blood thinners.

Remember to always consult with your health care provider before adding sea moss to your diet.