The Science Behind Premenstrual Food Cravings
Updated: Jan 9
Natalie Lam, HK BioTek Intern
As young women become “moodier”, notice tiny “volcanoes” or acne erupting along their oily face, and start to feel more bloated than before, they know that the “worst days” of the month are approaching.
Changes in hormones secreted by ovaries - such as estrogen and progesterone - may be responsible for producing these discomforting symptoms before menstruation or “period”, which are collectively known as the premenstrual syndrome (PMS).
Another PMS symptom, not mentioned above, is premenstrual food cravings. Unlike the PMS symptoms mentioned above, premenstrual food cravings may act as a response to unpleasant PMS symptoms, but they are not unpleasant in nature.
Premenstrual food cravings may correspond to increased energy demand in the female reproductive system in the luteal phase - a 14-day period leading up to menstruation. During the luteal phase, increasing progesterone levels promote the thickening of the uterus lining to prepare for a possible pregnancy. Since the thickening process requires energy, menstruating females would search for energy-dense foods to meet their increasing energy demand.
The changes in ovarian hormone levels during the luteal phase are also concomitant with changes in other types of hormones. In response, some women may consume heaps of food prior to menstruation. For example, estrogen and progesterone interact with mood- and appetite-regulating brain chemicals, including serotonin and GABA, which weakens their production or effectiveness. This effect overrides the brain’s appetite control and contributes to food cravings.
Nicknamed the “happiness molecule”, serotonin is a neurohormone that transmits signals related to hunger and mood-relaxation within the brain. However, a drop in estrogen levels and a surge in progesterone levels during the luteal phase decreases serotonin production, serotonin receptors, and sensitivities. Repressed serotonin levels may eventually lead to premenstrual depression, a PMS symptom which may be overcome by craving for foods that stimulate serotonin synthesis.
To anyone who has experienced premenstrual food cravings, have you noticed yourself eating more bananas or drinking milk before your period? It is interesting to note that despite being famously known to stimulate serotonin synthesis, almost no women with PMS have reported an increase in banana or milk consumption, but rather an increased consumption of carbohydrate-rich foods.
However, the idea that craving for carbohydrate-rich foods is self-medication for premenstrual depression and is not well-substantiated. Although a Cambridge researcher named Wurtman discovered that carbohydrates facilitate the uptake of nutrients required to make serotonin, and deliberate consumption of carbohydrates could improve premenstrual depression in women with PMS, more evidence is needed to prove that PMS sufferers are “obsessed” with carbohydrates before menstruation.
Receptors of GABA - a “relaxing” brain chemical - are also affected by an increase in progesterone levels in the luteal phase. These receptors are not only activated by GABA, but also by allopregnanolone (ALLO) - a molecule made from progesterone. Normally, ALLO interacts with GABA receptors to produce a calming effect. However, a surge in progesterone levels in the luteal phase decreases the sensitivity of GABA receptors to ALLO, which increases a woman’s susceptibility to premenstrual depression. This paradoxical effect coincides with Sundström’s (1997) finding that GABA receptors in PMS sufferers are less responsive than women without PMS.
Additionally, a decreased sensitivity of GABA receptors to ALLO increases a woman’s sensitivity to stress. ALLO normally inhibits the release of the “stress hormone” cortisol, but women with PMS have a delayed response to ALLO in the luteal phase. As a result, ALLO cannot effectively inhibit the release of cortisol. Under a double whammy of premenstrual “depression” and an ineffective stress response, food cravings serve as a coping mechanism.
All in all, if you feel low and experience premenstrual food cravings before your next “period”, remember that it is most likely due to changes in ovarian hormone levels, as well as altered interactions between ovarian hormones and brain chemicals.
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