You need to go on a diet of 2000 Kcal per day and increase your exercise.
Stop all sugar intake (use Sugar free, equals, splenda) to sweeten your tea/coffee, eat only two chappati / slices of bread with each meal, or one bowl of rice.
Fill your tummy with fruits like Papaya, apple and guava, or salads like cucumber, lettuce. You can eat any amount of vegetables cooked in small amounts of oil. Take the white of two boiled eggs every day and white meat like fist / chicken, also cooked in very small amount of oil.
Please maintain a diary for his daily intake and go for a run / walk for 45 min every day.
A sachet of EZLAX at night with water should ensure a good bowel movement next morning.
Recent onset constipation should be investigated by a colonoscopy