Losing weight

Hi Sumana,
Hypothyroidism is the condition in which, there will be inadequate production of the thyroid hormone that leads to various metabolic disorders including unwanted and undefined weight gain and lethargy. Moderate impact aerobic exercises,low calorie diet, swimming, Yoga and Pranayama are most effective tools that can help you to achieve your goal.
Regular walking - 4 Km a day for 5 days a week is also a good workout, may be your body has got adapted to it. I will suggest you to progress from walking to jogging.Also you can go for some other activity like skipping, stair climbing, swimming etc.
Also do some pranayama (breathing exercises) and Yogasanas like Sarvangasana (Shoulder Stand),Dhanurasana (Bow Pose) Sashankasana (Rabbit Pose) Matsyasana (Fish Pose) ,Simhasana (Lion Pose),Ustrasana (Camel Pose) etc. which can activate your hypoactive gland,thereby helping to regulate thyroid functioning.

Hi Sumana,
From your above description, its cleared that yo live an active life so you need to do more than just walking 4 km. Though walking for 4 km regularly is quite a good exercise but for your goal you need to change your regular pattern of exercise like give your body some changes like interchanging walking and jogging in between like walking for 15 min and jogging for 5 min and so on. This would help your body to burn more fat. And try walking more brisker than you walk at present. Also ,Hypothyroidism tends your body metabolism weaker so we can improve our metabolism by having small frequent meals and doing weight training exercises like push ups, lunges, squats, etc for atleast 20 min 2-3 /wwek for better results.
BEST OF LUCK !!

Hi

Useful points. Read this link also: http://www.lifemojo.com/lifestyle/losing-weight-with-hypothyroidism-5954779