What Could Be The Reason For Lack Of Energy And Appetite ?

hi read your query there could be a number of reasons for this 1. maybe he has developed diabetes or a thyroid disorder. without treatment such symptoms may occur suggest - fbs ppbs, tsh, HbA1C, urine ketones 2. he could have developed something called osa or obstructive sleep apnea. does he snore? is he overweight? does he have high blood pressures? you need a sleep study to prove this, but i would suggest you wait for other reports before we try this. 3. something significant in this query is that the symptoms started for the last 3 weeks. i am worried there may be a neuropsychological problem. could he be depressed about something? or anxious? is there any problem he may have developed, work wise or otherwise, causing depression/anxiety? besides we need to rule out a neurological problem. i would suggest an mri brain. 4. does he have any fever, or any vomitting or headache? i am worried about meningitis too. again mri brain will help. but a csf examination, after mri, is more diagnostic. 5. could be he has an infection causing this. a cbc with esr, urine routine, and culture of urine and blood would be needed to give a better comment. an x ray chest of course. i must say, you should meet a physician locally. without an examination, and a better history, it would be difficult to restrict the differential diagnosis. and therefore more and more tests would be needed but if you want to stick to my line of thinking, let me know the above reports and we can take it further from there best of luck