Losing weight can affect your menstrual cycle But how much weight does that mean?
Being skinny, or losing a lot of weight, shouldn't affect your
menstrual cycle unless it's a very drastic change. When you become
very skinny, your body decides that it's 'not fit' to have a baby,
so it halts the production of eggs, and hence the uterine lining,
which is what you shed (blood) during menstruation. No eggs, not
uterine lining, no period. So unless you lost A LOT of weight and
were OVERLY active, odds are you wouldn't have any problems.