Carnivore and Vyvanse

Anyone in here who takes Vyvanse for ADHD? Have you novices any change in how the medication works since starting the diet?

I take my meds in the morning on an empty stomach and usually don't eat until dinner time. I've noticed I get very tired/low motivation mid afternoon - could this perhaps be the medication no longer working? Maybe my body has become better at metabolising it? Before this it would last me till dinner/evening time.

Would love your input - also general inputs about how carnivore has affected your ADHD :))