I find it funny that the person going around telling everyone off has nothing to show for his arguments.
And why is cataracts out of whack? well an average moron will say it's because your eye seems like it has nothing to do with fat? Which is understandable. Unfortunately pathology isn't this simple. There's macromolecular pathology, and then there's small molecules. Macromolecular pathologies tend to happen in the same organ system while small molecular based pathology usually involve small molecules that are able to diffuse out of one organ and go to another.
Here's an article from a peer reviewed article stating the relation between cataracts and DNP usage.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1761212/
Now, I suppose I need to go into just a slightly more detailed explanation as to why DNP is dangerous.
As another anon suggested, DNP is involved in oxidative phosphorylation, AKA the ETC. ETC is the energy producing mechanism in your body. Essentially you're able to function because you are generating ATP (an energy molecule) from the ETC.
As I've already mentioned before, there are complexes 1-4, and then there is number 5, which is the ATP synthase. 1-4 uses other energy carreirs made elsewhere in the body to create a proton gradient to be used for ATP synthase in the generation of ATP.
What DNP does is a concept called uncoupling, which is seperating the proton gradient generating step from the ATP synthase step.
physiologically, this makes sense if you want to lose fat. Because you're artificially mimicing fasting state, which drives beta-oxidation, known to the general public as "fat burning" for energy.
So why is this bad? the proton gradient I mentioned above will be transported away by DNP, meaning complex 1 to 4 will continue to use energy carriers (NADH/FADH2) as well as oxygen without actually providing you ATP.