Here's some information I found on Fucoxanthin.
Fucoxanthin is being explored for weight loss. So far, only animal studies have been done. Japanese researchers have found that fucoxanthin (isolated from wakame) promotes the loss of abdominal fat in obese mice and rats. Animals lost five to 10% of their body weight.
Although it's not fully understood how fucoxanthin works, it appears to target a protein called UCP1 that increases the rate at which abdominal fat is burned. Abdominal fat, also called white adipose tissue, is the kind of fat that surrounds our organs and is linked to heart disease and diabetes. Fucoxanthin also appears to stimulate the production of DHA, one of the omega-3 fatty acids found in fatty fish such as salmon.
Although it's promising and already a popular nutritional supplement, more research is needed to determine if fucoxanthin will work in the same way in humans. If it does prove to be effective, fucoxanthin could be developed into a diet pill for obesity.