weight influencing periods?

How does weight change influencing periods? What are consequences? My best friend lost about 5kg and her problems with period started. She also trains 2-3h each day. Now she has it every 40-50 days. I believe that is because her diet. Am I right?

I think she caused secondary amenorrhea. Common causes are: pregnancy, lactation, young gynecological age, pregnancy, lactation, young gynecological age, anxiety, and eating disorders…although amenorrhea is attributed to exercise, it is more likely related to coexistent emotional stress, nutritional deficiencies. She should ask for professional help.