10 Reasons Why Seaweed Is Good For Weight Loss

Seaweed or marine algae are a perfect bundle of all-round nutrition.

It is one of the richest sources of proteins and nutrients.

Eating seaweed may seem unusual to you but it is a staple item of diet in Japan, China and Korea.

In the West, seaweed is considered as a health food and is now popularly consumed on coastlines.

Seaweeds belong to a group of microorganisms called algae.

Algae-based on their pigment is classified as red algae, green algae, blue algae, and brown algae.

There are around 21 species of seaweed that are used commonly in Asian cooking.

The most popular ones are:

  • Nori: It is purple-black seaweed with a high protein content of 30-50%.
  • Kombu: It is brown seaweed rich in iodine.
  • Wakame: It is brown seaweed with high total dietary fibre than other species.
  • Dulse: It is red algae which are rich in iron.

Commercially seaweeds are harvested for gelatinous material like agar, algainate and carrageenan which are used as food additives.

Seaweeds are rich in dietary fiber which implies its use in digestive problems.

Also as a fibre it helps in controlling appetite which can lead to weight loss.

10 Reasons Why Seaweed Is Good For Weight Loss

Quite a bit of study and research work has investigated the effect of seaweed and its bioactive components on obesity.

1. Seaweed burns fat

Fucoxanthin is a brown pigment found in brown seaweeds and other marine species. It is touted for its anti-obesity effect.

UCP1 is a protein that is expressed in brown fat which is the type of fat that burns fat rather accumulating it. White fat is the opposite- it accumulates fat rather than burning it.

Fucoxanthin consumption increases the expression of UCP1 in white fat tissue and leads to burning of fat.

Another mechanism by which fucoxanthin exerts anti-obesity effect is by modulating enzymes involved in fat metabolism and breakdown of fats.

Animal studies investigating the anti-obesity effect of fucoxanthin in face of diet induced obesity have revealed :
• Fucoxanthin reduces white adipose tissue- a tissue that accumulates fat.
• It lowers cholesterol and blood lipids.
• It prevents body weight gain.
• It improves metabolism of fat and glucose.
• It promotes excretion of fats.
• It positively regulates glucose and insulin levels.
• It reduces inflammation

In case you haven’t heard of MCT oil please read our article on Cooking Oils for weight loss. MCT or medium-chain triacylglycerol oil is a type of oil that doesn’t accumulate as fat but rather gets utilized immediately and raises metabolism in order to burn fats.

A study was conducted to compare the anti-obesity effect of MCT oil and fucoxanthin.

It was observed that fucoxanthin prevented weight gain better than MCT oil; but fucoxanthin’s anti-obesity effect was potentiated in combination with MCT oil.

Fucoxanthin’s anti-obesity effect was attributed to its ability to cause browning of white fat. Similar results have been proven about the combination of fucoxanthin and fish oil.

There has been only one clinical trial that investigates the effect of fucoxanthin supplementation in humans.

In this study, obese women with non-alcoholic fatty liver disease and those with normal liver fat content were recruited.

Xanthigen- a formulation of brown seaweed fucoxanthin and pomegranate seed oil was evaluated.

It contained 300mg of pomegranate seed oil and 300mg of brown seaweed extract containing 2.4mg fucoxanthin.

The study lasted for 16 weeks. Weight loss was 5.5kg in non-alcoholic fatty liver disease group and 4.9kg in the normal liver fat group.

Reduction in waist circumference, body fat, liver fat, liver enzymes, blood lipids, and inflammatory parameters was observed.

Xanthigen and fucoxanthin also increased metabolism.

An animal study also shows that Xanthigen’s anti-obesity effect is more potent than its individual components and acts on genes and enzymes affect fat tissue development.

These results suggest that seaweed extract can be a promising food supplement in the treatment of obesity and metabolic disorders.

What does this mean? Fucoxanthin is a pigment present in seaweeds which has anti-obesity effect. Animal studies and clinical trial suggests that it can help in modest weight loss and improve weight loss outcomes of other anti-obesity agents.

2. Seaweed extract has an anti-obesity effect

Fucodian is a type of sugar bound to sulphur found in various seaweeds, especially brown seaweeds. It also forms a jelly like the cover on sea urchin eggs and sea cucumber.

Fucodian prevents the accumulation of fats in fat cells by stimulating lipolysis or breakdown of fats.

Fucodian also inhibits adipogenesis- development of fat cells. It inhibits the expression of genes involved in fat cell formation and accumulation.

In an animal study, it was found that fucodian prevented diet-induced weight gain.

Additionally, a reduction in cholesterol and blood lipids was observed. Accumulation of fats in liver reduced.

Also, fucodian influenced the activity of genes involved in fat tissue development.

Fucodian also suppresses the production of inflammatory chemicals which aggravates the accumulation of fats in fat tissue.

Fucodian shows promise as a prospective anti-obesity agent.

What does this mean? Fucodian is a complex sugar present in seaweeds. It prevents diet induced obesity by preventing fat cell formation, fat accumulation and inhibiting activity of enzymes involved in fat digestion and absorption.

3. Seaweed extract reduces the absorption of calories from carbohydrate and fat

Seaweeds are rich in sugars, fibres, and antioxidants. Brown seaweeds are a rich source of fucodian, fucoxanthin, alginate and antioxidants. Each of these components affect the activity of digestive enzymes like glucosidase, amylase, pepsin, and lipase.

Alpha glucosidase is an enzyme that breaks down carbs into simple sugars.

Seaweeds inhibit the activity of this enzyme which results in a positive effect on blood sugar control and can also limit simple sugar absorption from intestines.

Another type of edible seaweed, Ascophyllum nodosum is found to inhibit the activity of alpha amylase- another enzyme involved in carbohydrate absorption.

Alginate, a type of dietary fibre found in seaweed is proven to inhibit the activity of enzyme lipase which is responsible for fat digestion and absorption.

Herbidean brown seaweeds inhibit the activity of lipase and can be useful in weight management.

What does this mean? Seaweed extracts inhibits the activity of various digestive enzymes which affects absorption and digestion of dietary fat and carbohydrates. This in turn can reduce the number of calories made available to the body.

4. Seaweeds reduces fat accumulation

\Alaskan seaweeds are found to reduce fat accumulation by 55% by increasing the level of hormone-adiponectin which mobilizes fat and prevents its accumulation.

Additionally, it is said to reduce obesity-induced inflammation.

An animal study was conducted to evaluate the effect of edible seaweed consumption on diet induced obesity. The seaweed evaluated was Geldium amansii.

It was observed that 12 weeks treatment of edible seaweed reduced body weight despite of being fed a high-fat diet, reduced formation of fat cells, improved glucose metabolism, and reduced cholesterol levels.

Researchers concluded that Geldium amansii supplementation can benefit in the treatment of obesity.

Similarly, seaweeds of Jeju island have shown an inhibitory effect on fat accumulation in fat cells.

Powder of brown seaweed Sargassum polycystum reduces diet induced weight gain. Its rich fibre content and presence of fucoxanthin supports its anti-obesity effect.

What does this mean? Seaweed intake reduces fat cell formation and reduces fat accumulation and can thus protect from diet induced obesity.

5. It controls appetite

Seaweeds contain viscous fibers like alginate which when consumed increase the fullness feeling, reduce appetite and energy intake.

Alginate when consumed increases in volume with water absorption thus giving a feeling of satiety.

It delays gastric emptying, increases the viscosity of digested material and slows down the absorption of nutrients in the intestine.

Jensen et. al studied the short term effects of alginate consumption on appetite. Individuals were given either low volume (9.9g) or high volume alginate (15g) based drinks or placebo drink prior to breakfast and lunch.

A 5.5% reduction in appetite was observed with high volume alginate beverage.

When the same researchers conducted the study for a period of 12 weeks with the inclusion of a low-calorie diet, it was observed that weight loss in alginate group was around 6.78kg compared to placebo 5.04kg and most of this weight loss was attributed to reduction in body fat.

Paxman et al has demonstrated that daily consumption of sodium alginate reduces daily energy intake by 7%.

Odensi et. al conducted a 10-day clinical trial in which they supplemented obese individuals with 3 alginate capsules 30 minutes prior to three main meals. It was observed that alginate did not affect gastric emptying or hormones related to appetite and satiety.

Overall review of studies conducted on alginate consumption and appetite, suggests that alginate consumption does suppress appetite and energy intake.

Alginate supplementation affects glucose control and insulin secretion.

A study was conducted to assess whether whole seaweed rather than alginate consumption will aid in controlling appetite.

Bread enriched with seaweed Ascophyllum nodosum was given to healthy individuals at breakfast and the effect on appetite at lunch was studied.

It was observed that there was a 16.4% reduction in energy intake at lunch. Also, incorporation of seaweed in bread was found to be palatable.

What does this mean? Both whole seaweed and alginate serve as excellent source of dietary fibres which on consumption increase fullness by absorbing water and swelling. This reduces appetite and further calorie intake.

Seaweed Is Good For Weight Loss

6. It controls blood sugar levels

Obesity induced diabetes or insulin resistance is a major health hurdle.

When cells fail to respond to insulin glucose metabolism is hampered and then glucose is either stored as excess fat or we tend to suffer from excess blood sugar which is called hyperglycemia.

Research shows that seaweeds inhibit the activity of enzymes- alpha glucosidase and alpha amylase.

These enzymes are involved in carbohydrate absorption and digestion.

Irish brown seaweed extract is proven to inhibit the activity of these enzymes and can aid in preventing hyperglycemia or rise in blood sugar levels.

Fucoxanthin found in brown seaweeds has an anti-diabetic effect.

A clinical trial was conducted wherein obese or overweight individuals were given 500mg fucodian or placebo for 3 months.

A decrease in bad cholesterol and improvement in insulin levels and pancreatic beta cell function (cells responsible for insulin secretion) was observed.

What does this mean? Seaweed consumption improves blood sugar control and prevents insulin spikes. It is important that glucose metabolism is not hampered else it can contribute to weight gain.

7. It reduces cholesterol levels

Alginates and other viscous fibers present in seaweeds bind to cholesterol and other lipids to form a complex and promote their excretion.

A clinical trial on humans suggests that a 1.5g intake of alginate can reduce cholesterol and glucose levels.

Result of a clinical trial shows that the consumption of seaweed (48g daily) reduces blood sugar levels and improves good cholesterol levels.

Improvement in antioxidant defenses was also observed.

Green seaweeds are proven to reduce cholesterol levels and thereby reduce the risk of metabolic and heart diseases.

Dietary seaweed reduces hypercholesteremia- a health condition with high cholesterol levels.

Fucoxanthin also affects cholesterol levels. Dietary fucoxanthin affects the genes involved in cholesterol synthesis and reduces cholesterol levels.

What does this mean? Excessive weight gain can pave way for high cholesterol levels and metabolic diseases. Seaweed supplementation can reduce cholesterol and improve metabolic health.

8. It is rich in minerals and vitamins

Seaweeds are rich in minerals like iron, zinc, magnesium, calcium, and iodine. It is rich in vitamins A, B12, and C.

Seaweed is a rich source of iron. Dietary supplementation of seaweed is found to improve iron status in anemic individuals.

Supplementation with minerals and vitamins has an indirect effect on weight loss for eg: they are essential in various life processes and metabolism.

Mineral and vitamin deficiency can occur in obesity. (Read Are Vitamin Levels Connected To Obesity?-Truth Revealed, How Minerals Play An Important Role In Weight Management)

What does this mean? Seaweeds provide a rich source of vitamins and minerals whose supplementation is essential and can accelerate weight loss.

9. Seaweeds improve digestion and work as prebiotic

Prebiotic foods are those that serve as food for the bacteria that are residing in the gut and these bacteria aid in digestion and absorption of nutrients.

They benefit the growth of gut bacteria whose population is impaired in obesity. Polysaccharides or complex sugars found in seaweeds serve as prebiotic agent.

Liu et. al conducted an animal study to investigate the prebiotic effect of red seaweeds.

It was observed that red seaweed supplementation increased the population of beneficial bacteria like Bifidobacterium breve and reduced the number of pathogenic bacteria like Clostridium and Streptococcus species.

It also improved immunity.

Proteins isolated from red seaweed also improve gut function, exert an anti-inflammatory effect and improve immunity.

What does this mean? Proteins and carbohydrates found in seaweeds have prebiotic effect. This is beneficial in improving gut health in obese individuals.

10. It is a low-calorie food item

Around 100g of seaweed provide only 43 calories with 0.6g of fat and 1.3g of dietary fibre. 2tbsp or 10g of wakame provides only 5 calories.

Presence of dietary fibre and the absence of fats is what makes it low calorie.

The fibres are undigestable and hence don’t contribute to calories.

In Asia, seaweeds are used in salads and soups as low-calorie dietetic foods.

Dietary fibre constitutes 25-75% of dry weight of the marine algae, most of which is soluble fibre.

The soluble fibre has high water holding capacity due to which it absorbs water, swells in the stomach and decreases appetite.

The fibres affect digestion and fermentation in the intestines.

Sugars found in seaweeds reduce cholesterol levels. These aren’t the type of sugars that would cause weight gain.

What does this mean? Seaweeds provide very low calories which makes it a perfect snack for weight loss.

Other Health benefits of Seaweed

Seaweed has a number of other health benefits like:

1. It is a rich source of protein.
2. It is a good source of iodine which can benefit thyroid function.
3. It has anti-inflammatory and antioxidant properties.
4. It has anti-bacterial and anti-viral properties.
5. Some of its compounds like fucodian exert anti-cancer effect.
6. It can prevent heart problems and diabetes.
7. It shows potential in treatment of hypertension.
8. It boosts immunity.
9. It serves as plant source of hormone or phytoestrogens.
10. It works as a natural detoxifier.

How much and how to take Seaweed for weight loss?

A serving of seaweed would be somewhere around 10g. So 1-2 servings or around ½ cup of seaweed should be fine.

Nori is used to wrapping sushi and other snacks. Kombu is sold as 5-6 inches pieces, as powder, boiled or even pickled.

Dried kombu needs to be boiled to soften it. In general, most seaweeds need to be boiled or soaked in water before cooking.

You can add seaweeds to soups, salads or even boil it with rice preparations. Powdered seaweeds can be added to drinks or sprinkled on foods. You can even cook seaweeds in olive oil till they become crisp.

If you opt for fucoxanthin supplements, the dose used in somewhere around 2-8mg. It is best to consult a doctor before taking fucoxanthin supplements. It is best to include seaweed in diet, for that supplies more than just fucoxanthin.

Study - Brown seaweed & Weight Loss

This study was conducted over a period of 16 weeks. 151 obese premenopausal women, some suffering from non-alcoholic fatty liver disease and other healthy were recruited.

They were given brown seaweed extract with different doses of an active compound, fucoxanthin.

What were the results of this study?

Statistically significant reductions in body weight were observed. Average weight loss was 5.5 kg in NAFLD group and 4.9kg in a normal fat liver group.

Body fat loss was around 3.5 kg and a decrease in waist circumference was also observed.

Improvement in liver fat content, liver enzymes, and blood lipids occurred.

The extract also caused an increase in metabolic rate in individuals suffering from NAFLD.

Brown seaweed extract helps in managing obesity

How did this occur?

Fucoxanthin is the active compound of brown seaweed and contributes to the color of brown algae. This compound has anti-obesity potential.

It raises metabolism and impacts fat metabolism. It suppresses diet-induced obesity. It restricts the accumulation of fats in the fat tissue and improves cholesterol and blood lipids.

It also helps in the maintenance of normal blood sugar levels.

All these mechanisms together favor good metabolic health and impact body weight.

What does this mean?

It was concluded that brown seaweed extract promotes weight loss and normalizes liver fat content which is therapeutic for obese individuals suffering from metabolic conditions.

Brown seaweed extract is thought to be a promising weight loss supplement.

Apart from taking supplements, certain cuisines also include brown seaweed, for example, the Korean cuisine, which you could try if you are up to it.

Read the paper here: http://www.ncbi.nlm.nih.gov/pubmed/19840063


Seaweeds are a natural food source and not likely to cause significant side effects.

However, it should not be consumed in high amounts, since its fibre content may affect digestion.

Also, seaweeds are a rich source of iodine and iron; so it is advisable to take precautions if suffering from thyroid problems and anemia.

No drug interactions have been identified.

The high vitamin K content of seaweed may pose a problem if you are consuming warfarin. It is advisable to consult a doctor before taking seaweed supplements.


Seaweeds are a low-calorie package but high on nutrients.

Its dietary fibre content helps in reducing appetite. Seaweeds also possess some great anti-obesity compounds like fucoxanthin and fucodian.

Research on seaweed’s anti-obesity effect is mostly based on animal studies and more clinical trials are required to confirm its role in weight loss.

But keeping mind the nutrients it provides and the potential anti-obesity components it contains we would recommend seaweeds for weight loss.



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