there is not much evidence that fructose is worse than glucose, but in principle part of it is because fructose permeates cells via diffusion while glucose must

there is not much evidence that fructose is worse than glucose, but in principle part of it is because fructose permeates cells via diffusion while glucose must be pumped into the cell; so it consumes more energy to produce energy from it. There's also differential ability of different cells in the body to process glucose vs fructose