like my BMR is 1600 calories a day if i layed in bed all day

well with mono i do lay in bed all day, and cannot exercise

so as long as i do not exceed 1600 calories, will i not gain any weight

im kinda freaking out because the last 3 months ive been working hard to lose weight

and my doctor says i may have mono which lasts like a couple of months

so im afraid i will gain all my weight back because i have no energy to exercise, and i could rupture my spleen if i do exercise