Why Do I Feel Sleepy Hungry And All The Time?

hi doctor i am 21 yr old female as i m a bit fat i started my exercise &morning walk since 1 month days use to be good but since a week i'm unable be active in my office i feel sleepy al time, i'll yawn often & loose my concentration towards my work & i feel hungry too. as i go to bed at 10:30 & wake up at 6 i'm worried if i loose my job because of dis so i would be glad if i get a relevant suggestion please do the needful thank you..