Can Adding Kelp to Your Diet Help You Lose Weight?


Hate to burst your bubble, but there are no “magical” weight loss foods that will melt off extra pounds of body fat and give you a svelte figure. People like the idea of quick, simple results but it’s an illusion. The totality of your diet matters most for weight control, and you also have to move your body more to burn extra calories and maintain a healthy body composition.

However, some foods may give you an edge in fighting body fat. For example, eggs are a high-quality protein that helps with appetite control and vegetables are a rich source of fiber that increases satiety and curbs cravings. But there’s another food you hear less about that may help you fight an expanding waistline. This food is an excellent source of over 30 vitamins and minerals and an important part of the Japanese diet. If you haven’t guessed by now, it’s kelp, a type of sea vegetable.

Kelp isn’t a food most Americans eat regularly. But when you look at the slim bodies of many Japanese citizens and the fact that their average life expectancy exceeds that of Americans by five to seven years, maybe we should!  And there’s more good news about kelp. According to research presented at the American Chemical Society Meeting in San Francisco, an ingredient in kelp could help with weight loss.

Kelp for Weight Loss

Kelp is a sea vegetable, brown algae, that the Japanese use to flavor soups, rice dishes, and some snack foods. It has a naturally salty taste that makes it appealing as a snack food. Plus, it’s healthier than chips. At some health food stores, you can buy bags of seaweed chips and other crunchy snacks made of kelp.

Kelp is low in calories but rich in vitamins and minerals, including iodine, a mineral that’s important for thyroid function. This brown, leafy sea vegetable is also an excellent source of a fiber-like carbohydrate called alginate. Scientists at the University of Newcastle believe the alginate in kelp could help with the battle against obesity.

When you eat kelp, it exposes the alginate to water in the intestinal tract and the alginate sucks it up voraciously. In fact, alginate can absorb up to 300 times its weight in water. When it does, it forms a thick, gum-like substance in the intestines that binds fat. You can see where this is going, right?

When researchers at the University of Newcastle tested the alginates in sea kelp in an artificial intestine, they discovered this fiber-like substance reduced the absorption of fat by the intestines by a whopping 75%. Less fat absorption means fewer calories, which could make it easier to lose weight. The researchers in this study hope that adding alginates to common foods such as bread and pasta might reduce how much fat people absorb from food and help with weight loss and weight control.

More good news: one study found that alginates block the activity of an enzyme called lipase that aids in fat absorption. So, you may absorb fewer calories from the fat you eat if you consume a diet rich in fucoxanthin.

Another compound in kelp and other sea vegetables called fucoxanthin, a type of fiber, may also help with weight control based on some research. Most of us could use more dietary fiber.

Other Health Benefits of Kelp

Kelp is one of the best natural sources of iodine, a mineral that’s important for thyroid function. The thyroid is a gland in the neck that regulates metabolism and body temperature. People deficient in iodine may have an under-active thyroid and a slower metabolism that makes it harder to lose weight.

Iodine plays a key role in making active thyroid hormone. Your thyroid gland takes up iodine and uses it to make triiodothyronine (T3) and thyroxine (T4), the active forms of thyroid hormone that determine your metabolic rate. Therefore, you need iodine for normal thyroid function. However, the evidence is lacking that adding more iodine to your diet helps with weight loss if you’re not iodine deficient. In fact, too much iodine may contribute to autoimmune thyroid disease. It’s an example of more not always being better. Plus, consuming large quantities of iodine could cause an overactive thyroid.

Other benefits? Kelp is also rich in vitamins and minerals and an excellent source of iron, magnesium, and calcium. A serving of kelp contains vitamins A,C,E, and K, as well as some B-vitamins. It also contains antioxidants that help fight oxidative stress that damages cells.

Does Kelp Suppress Appetite Too?

According to a study published in the journal Appetite, the alginates in kelp keep appetite in check too. This isn’t surprising since alginate forms a gel-like substance in the intestines that expands. When researchers gave alginate to a group of participants, they ate an average of 135 fewer calories over a 24-hour period.

Should You Add Kelp to Your Diet?

Don’t overstock your cabinets with kelp. These results are preliminary and need further confirmation with more human studies. However, kelp is vitamin and mineral-rich. In addition, one study showed it reduces levels of estradiol, the most potent form of estrogen. Lowering levels of this form of estrogen may reduce the risk of breast cancer and other estrogen-related cancers.

There is one problem with adding large amounts of kelp to your diet. Kelp can absorb heavy metals from the waters they grow in, and some kelp supplements have tested positive for inorganic arsenic, a heavy metal linked with health problems, including cancer.  If you add kelp to your diet, choose kelp grown in deep waters near the ocean floor. It contains fewer heavy metals and other contaminants. Don’t eat kelp if you have a history of an overactive thyroid or autoimmune thyroid disease.



  • Science Daily. “Seaweed to Tackle Rising Tide of Obesity”
  • Nutraingredients-USA.com. “Study Reports Arsenic in Kelp Supplements”
  • Science Daily. “New Study Finds Kelp Can Reduce Level of Hormone Related to Breast Cancer Risk”
  • Appetite. 2008 Nov;51(3):713-9. Epub 2008 Jul 4.
  • EndocrineWeb.com. “How Your Thyroid Works”
  • Food Chem. 2014 Mar 1; 146(100): 479–484. doi: 10.1016/j.foodchem.2013.09.075.
  • Mar Drugs. 2016 Dec; 14(12): 222.Published online 2016 Dec 7. doi: 10.3390/md14120222.
  • Cherry P, O’Hara C, Magee P, McSorley E, Allsopp P. Risks and benefits of consuming edible seaweeds. Nutr Rev. 2019;77(5):307-329. doi:10.1093/nutrit/nuy066.
  • World Health Organization. “Cancer”


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