Low-Carb Diet & Multiple Periods: What the Science Says

There is no scientific evidence that a low-carbohydrate diet causes two menstrual periods in one month (polymenorrhea). The menstrual cycle is governed by the hypothalamic-pituitary-ovarian (HPO) axis and ovarian steroid feedback (estradiol, progesterone). While severe caloric restriction, rapid weight loss, or very low body fat can disrupt GnRH pulsatility → anovulation/amenorrhea, macronutrient composition alone (low carb) does not directly shorten the cycle.

What Can Alter Cycle Frequency?

• Energy availability: Low energy availability (LEA) → functional hypothalamic amenorrhea.
• Stress (physical/psychological) → HPA axis suppresses HPO axis.
• Thyroid dysfunction, hyperprolactinemia, PCOS.
• Perimenopause – cycles shorten then become irregular.
• Uterine pathology (polyps, fibroids) – intermenstrual bleeding mistaken for second period.

Practical Advice

If you experience bleeding twice in one month, track dates/flow and consult a clinician. A low-carb diet per se is unlikely the cause; evaluation should focus on hormonal, structural, and systemic factors.