rises in estrogen tend to suppress appetite, whereas a dip in the hormone, combined with elevated progesterone, stimulates appetite. As a result, in the first half of your cycle, your metabolism slows down, curbing your appetite and conserving nutrients in anticipation of a possible pregnancy. During the luteal phase of your cycle, energy expenditure jumps anywhere from 8 to 16 percent, according to foundational research from 1986 in the American Journal of Clinical Nutrition. That jump corresponds to burning an extra 89 to 279 calories a day.
