Symptons of anorexia can cause you to have irregular or absent menstrual periods. Excessivley low body weight interrupts many hormonal functions in the body,  which causes women who suffer from an eating disorder to have absent menstrual periods. Feeling cold all the time which is also considered as hypothermia is another symptom of Anorexia because of lack of body fat. 

An obsession with counting your calories can also be a symptom esspecially wanting to only consume the smallest amount of calories. 

Your body can also give you many signs as well,  these signs include feeling dehydrated,  dizziness,  fainting,  fatigue,  low blood pressure,  and low body temperature. 

if you are experiencing any of these symptoms it is recomended too seek a mental health professional,  such as psychologist or therapist for talk therapy.  It is also best to seek a registered dietien to educate you about nutrition and meal planning. 

https://www.mayoclinic.org/diseases-conditions/eating-disorders/in-depth/eating-disorder-treatment/art-20046234