These problems are related to disturbed sleep cycle with decreased food intake leading to lethargy.
You need to balance your work, sleep, eating, exercises.
If you have an option of switching over to day work for sometime, that will help you.
If not, you can change your food eating habits as per your work schedule.
Take meal when you come back from office in morning.
Take proper sleep of 7 to 8 hours.
After waking up, take light snacks with milk/tea, followed by a proper meal before you go for night shift.
It will take body clock to adjust but should settle down.
Also, if possible take out some time for exercises after you're back from office or before going, whatever is convenient.
Next Steps
Visit a Physiotherapy centre who can help you with exercises for weight loss. Also, you can start with yoga for same.
Health Tips
Avoid eating too much while in office.