I preferred to eat meat every day since I remember. I tried once lately for a couple of days to not eat meat. Mainly eating tofu as a substitute with some lenti

I preferred to eat meat every day since I remember. I tried once lately for a couple of days to not eat meat. Mainly eating tofu as a substitute with some lentil. On third day of such a diet I was feeling very bad. I was feeling weak, nauseous and a bit shaky. I tried to eat sugar in form of candy bars. It passed after I have eaten a few sandwiches with lots of meat. Was it wrong what I did? Is my body programmed to digest meat and can't easily switch to other sources of protein? When I'm not eating meat I feel weaker.