To feel really irritable after doing this

[Fitnessstep]

I’ve started lifting weights in recent months, I really enjoy it but feel so groggy and irritable afterwards. If I’m doing cardio then I don’t feel like that though.

Has anyone else experienced this? It’s really odd, I’ve no idea what causes it.

In cycling it's called a bonk, due to depletion of blood sugars. You need to ensure you are eating correctly prior to and after working out.

Being an older man I work out first thing then have breakfast

Interesting, I’ll look into that.