Just out of curiosity?

You have to be quite overweight for it to affect your period. Like morbidly obese kind of range. If you mean this is your first period in 4 months, if this happens again it'd be worth going to the doctor as that degree of delay can indicate all kinds of things, including PCOS. If you just mean it's been late a day or two each of your last two cycles, a) up to 4 days variation is considered medically normal, b) your cycle might have changed, especially if you're quite young, and