The 60-plus pounds he gained for his role as Mark David Chapman in "Chapter 27" was Jared Leto's explanation for the plastic clogs he was wearing recently at Chicago's Hard Rock Hotel. His diet and weight gain caused him to develop gout, a painful form of arthritis which causes toes to swell due to a buildup of uric acid crystals in the joints. Sounds painful, and I'm sure those plastic "Croc" clogs helped ease the pain.
Gout is often thought to be a disease of laziness - caused by lack of physical activity, a diet high in alcohol and rich foods and low in fruits and vegetables. This may be linked to one's metabolism of purine, an organic compound that is broken down by the body into uric acid. Eating high-purine foods such as meats and alcohol, and avoiding purine-neutralizing foods such as berries and fresh vegetables can therefore cause gout in those predisposed to it. In extreme cases, surgery may be necessary on the inflammed joint. I'm sure Jared is working hard to lose the weight and hopefully he can put this whole swollen-toe episode behind him soon.
(Jared Leto) Suffers For Art [Page Six], Gout information thanks to Wikipedia