A few days ago I realised that I had been under-eating pretty badly. In the month before that, I was running much slower in all of my workouts/races despite them feeling much harder than usual. Started eating a lot more and now I feel like I have far more energy. Easy paces have returned to normal, and feel far less taxing on my legs.
My question is, will the training that I did whilst under-eating/overtraining still be beneficial and have a positive effect? Or should my fitness be back to where it was before I started underperforming?