Hi There, For Nearly Six Years I Was Greatly Mistreating

Hi there, for nearly six years I was greatly mistreating my body with poor diet and little exercise but recently I decided to fix that. I have been make gradual alterations like going to the gym and started eating fruit again and reducing calorie intake but a few days after I started I have been experiencing symptoms such as dizziness, sick stomach, regular bowel issues and lack of sleep. Could this be linked at all to the change in diet?