When you start eating more, your body is forced to wake up
and start digesting,
and the shock to your system causes an increase in
heart rate that may manifest itself over a long period of time.
Luckily, our bodies and our hearts are tough, and are able to adjust. It will take time, but I'll bet that after you're fully recovered, your heart rate will slow and your health will be better than ever. Keep eating, and believe in the power of your body to be healthy once more.