Increased appetite and intense cravings in the days leading up to menstruation are a widely reported physiological phenomenon. Many people notice a distinct shift in their eating patterns, consuming more calories and specifically desiring certain types of food. This change is not a matter of willpower but is driven by predictable shifts in the body’s biology. Heightened hunger and specific food desires before a period are rooted in fluctuating reproductive hormones, an increase in the body’s resting energy needs, and a neurochemical attempt to manage mood.
The Role of Hormonal Fluctuations
The primary driver of increased premenstrual hunger is the dramatic shift in reproductive hormone balance that occurs after ovulation. During the follicular phase, estrogen dominates and functions as a natural appetite suppressant. Following ovulation, estrogen levels decline sharply while progesterone levels increase significantly, which is associated with a rise in appetite and food consumption. This hormonal environment tells the brain’s hunger centers to increase caloric intake.
This hormonal signaling is a vestige of the body preparing for a possible pregnancy, as the thickening of the uterine lining requires substantial energy investment. Studies comparing food intake between the two cycle phases note that a person may consume anywhere from 200 to 600 more calories per day in the luteal phase. This hormonal interplay is the most significant biological cause behind the feeling of deep hunger.
Metabolic Changes and Energy Expenditure
Beyond hormonal signals, there is a genuine, physical increase in the body’s need for fuel. The body’s basal metabolic rate (BMR) rises during the late luteal phase, contributing to a true physiological hunger. This increased energy expenditure is mediated by the thermogenic effect of progesterone.
Progesterone stimulates the sympathetic nervous system, causing a slight elevation in core body temperature. Maintaining this higher temperature requires the body to burn more calories, increasing the resting energy cost. The increase in BMR is often reported to be a significant rise of up to 6% above the follicular phase rate. This means the body genuinely needs an estimated 100 to 300 extra calories per day to maintain this higher resting state.
Neurochemical Drivers of Specific Cravings
Cravings are often for specific comfort foods high in carbohydrates, sugar, and fat. This preference is strongly tied to the brain’s attempt to regulate mood using specific neurotransmitters. The fluctuating ovarian hormones, particularly the decline in estrogen, affect the production and function of serotonin.
Lowered estrogen levels in the luteal phase can lead to a drop in available serotonin and reduced receptor sensitivity, which contributes to the mood swings and tension associated with premenstrual syndrome (PMS). Consuming carbohydrate-rich and sugary foods provides a temporary boost to serotonin levels. The body achieves this by increasing the uptake of tryptophan, an amino acid precursor to serotonin, into the brain following a carbohydrate meal. The intense desire for sweets and starches can thus be seen as a form of biological self-medication, stabilizing mood and alleviating emotional discomfort.