I wear a button on my ID tag that proclaims that I am "High in Fiber." It's to show that 1) I am a member of a profession that educates people on fiber needs (or not), 2) I enjoy "fiber arts" such as knitting, crocheting, and possibly spinning, and 3) I have the sense of humor of a twelve year old most days. Yesterday I was in a circle of people who were all beginning spinners and we were all commiserating on the difficulties of learning spinning. I've noticed that sometimes said comraderie leads to commiserating and trading tips on other things, and in this case it happened to be upcoming surgeries and weight loss. My favorite for this event? "I started drinking two tablespoons of chia seeds in water and in two days I lost three pounds!"
"Wait, aren't chia seeds what you use to grow the 'fur' on those terra cotta figurines feature in those annoying commercials?" is probably what you are thinking. Well, yes, they are from the same plant, but now the seeds are being sold to help [insert your favorite health problem here], including helping people lose weight. The theory is, if you put chia seeds in water they form a gel, and that gel helps you "feel full" faster, and then you don't eat as much, so you can lose weight. (Although I think the person who said this just heard "they are supposed to be good for losing weight" and stopped there). Since the use of chia seeds also date back to Mayan and Aztec cultures, I think there might also be an "appeal to ancient wisdom" fallacy at play here, as well as an "it's exotic so it must be good for me" fallacy. Does this theory hold up in practice though?
There was actually a single blind study done in 2009 that indicated that chia seeds didn't help change body composition after 12 weeks (Link). Think about it this way too, even if the addition of chia seeds did help you eat less at breakfast (or whatever meal you decided to take them), if you didn't get enough protein and/or good fats for satiety (or just overate on carbohydrate and messed with the hormones like insulin that play a role in regulating appetite), you will probably try to make up for what you didn't eat at breakfast later on. So why did that person in your knitting circle lose weight after adding chia? Chances are they made other changes in their eating habits that promoted weight loss.
Is there any other benefit to adding chia? Possibly, depending on what other things you are or are not eating. Chia seeds are a good source of omega-3 fats, so if you don't eat fish on a regular basis or don't wish to supplement with fish oil you could use this as one of your sources. Keep in mind that the form in non-animal sources (alpha-linolenic acid or ALA) is not as efficiently absorbed as animal sources (docosahexaenoic acid or DHA, and eicosapentaenoic acid or EPA), so if you are vegan or vegetarian you really want to make a point of working those in! (Flax seed also works, but you have to make sure you grind the flax seeds to actually absorb the good things!). If you are someone that has trouble eating fruits and vegetables (you know you should eat more vegetables, but you haven't make it yet), chia seeds can help you get some anti-oxidants and fiber. And if you have irritable bowel syndrome, the soluble fiber in chia can be good for helping absorb water so the stool can be more formed (diarrhea dominant) or softer and easier to pass (constipation dominant). 2 tablespoons of chia can actually give you about 6 grams of protein (about the same amount as one egg), so carbohydrate-concious vegetarians/vegans can use this as a way to work some protein in as well.
Take home message--there could be benefits to including chia seeds, especially for vegans/vegetarians, just don't expect any magic weight loss attributes.