Someone told me about this thread (and Bryan's been bugging me to post here anyhow) and I see my name is being taken in vain as usual.
Couple of comments.
1. All of the studies on glucosamine and leptin are in vitro, that is, they add it to cell culture. I highly (highly, highly) doubt that oral glucosamine is going to have any effect. It's not absorbed well enough orally in the first place, and blood flow to the fat cells is too poor. I don't know if it would work topically (i.e. DMSO or something), would depend on how big it is. I kind of doubt it. I know it is big, which is why its absorbed so poorly. Incidentally, some research suggests that it's the sulfate part of glucosamine sulfate having the main effect, NOT the glucosamine. Which would make sense considering how little glucosamine actually gets into the bloodstream.
2. EPA doesn't work through the hexosamine biosynthetic pathway as someone stated (the HBP is simply a nutrient sensing pathway in both muscle and fat cells which 'tells' the cell how it's doing on nutrients, by changes in glucose metabolism in the cell). EPA works via the PPAR nuclear pathway (PPAR gamma is the main receptor in fat cells, PPAR alpha is in muscle cells). I'm too tired and spaced out right now to type out what PPAR stands for; can't sleep for some reason.
3. In the studies where EPA decreased leptin levels, it was because the EPA caused the fat cell to lose fat. It's easy to confuse what's doing what for this reason.
And that's the bottom line: any time you pull calories out of fat cells, leptin levels go down, becuase of changes in hexosamine levels (it has to do with levels of an end product with this horribly complicated name that I can never remember; when that end product goes down, the fat cell 'knows' it's losing calories, and leptin production goes down). I tried to find ways to 'trick' the pathway but I don't think it can be done. I will be curious to see what's in Leptigen though. I have a few guesses on the ingredients but am waiting to see.
4. Yes, it would be ideal to maintain leptin levels at a normal level while dieting. Finally, a recent study tested this (all of the previous leptin studies were using it wrong). Dieted folks and then gave them just enough leptin to return levels back to baseline. It corrected metabolic rate, thyroid levels, and caused further fat loss. Well, duh (sorry, I'm cynical, I knew this was how leptin should be used two years ago and the researchers just now caught up). For the time being, high carb, high calorie refeeds are really the only way to naturally bump leptin. You still can't get it back to where it needs to be.
Lyle
