Can Diet Pills Effect Your Menstrual Cycle?

Many women experience an irregular menstrual cycle sometime in their lives. This may last for a short time or may be a lifelong feature of their cycles. Causes include polyps, breastfeeding, chemotherapy, stress and drug use. Diet pills fall in this last category, and often knock menstrual cycles off kilter. If you suspect your attempt to lose weight might be causing irregular periods, consult your doctor.

Nutrient Deficiency

Nutrient deficiency is one common cause of irregular periods, according to OB/GYN nurse practitioner Marcelle Pick. Diet supplements, especially those that are advertised as alternatives to meals, may lack the vitamins necessary to keep everything in working order. Pick warns that nutritional deficiencies caused by dieting might cause other unhealthful effects in addition to skipped periods.

Stress and the Menstrual Cycle

Stress is another common reason for menstrual irregularities. When you're stressed, your adrenal glands secrete a hormone called cortisol, which impacts estrogen, progesterone and DHEA, which are all hormones tied into the reproductive cycle. Your body interprets many things as stress, including dieting, stimulants and drug use. If diet pills are adding to your other sources of stress, it might be time to put them back in the cupboard and try to lower your stress by exercising, meditating or chatting with a friend.

Not Enough Fat

Periods can stop when a combination of dieting, diet pills and too much exercise result in inadequate body fat. Sometimes women perceive themselves as heavier than they are, and don't know when to quit dieting. If your body fat drops low enough, estrogen levels fall and ovulation stops. This condition is called stress-type hypothalamic amenorrhea and is common in anorexics. These overzealous dieters put themselves at risk for degenerative conditions like osteoporosis.

Types of Diet Pills

Doctors may prescribe diet pills for obese patients, and many supplements and pills are available over the counter. These pills work in different ways. Some, like the prescription pill Xenical and the over-the-counter pills Chitosan and guar gum, work by blocking or decreasing absorption of dietary fat. The fat passes right through, often with messy side effects. Bitter orange and chromium claim to increase the number of calories burned. Hodia, green tea extract and ephedra allegedly decrease the appetite. According to, the safety of most of these pills and supplements range from unsafe to debatable.


Irregular periods are only one possible consequence of diet pills. Xenical has especially unpleasant side effects, according to the Net Doctor website, including sudden bowel movements, oily spotting from the rectum and possibly preventing the body from absorbing fat-soluble vitamins. Somewhere between one in 10 and one in 100 women report irregular menstrual cycles while on Xenical. The FDA has banned the diet supplements ephedra and country mallow.