They had an issue with weight restriction once out of NRT as I was trying to get back to Conus. But it had more to do with the unusual warm spell they had there, temperatures in the 90's causing them to weight restrict because of fuel. When its warm, the high temp and high humidity causes aircraft fuel to not burn as efficient and lean requiring more thrust for takeoff which means weight becomes more of an issue in the calculation. Another issue with weight restriction has to do with elevation. (Density altitude.) The higher you go in the air, the less dense the air is, the molecules are farther apart...never mind, read this. All should know this.

Density altitude - Wikipedia, the free encyclopedia