How to lose weight is a sensitive issue and the question could have more than one correct answer. Finding the correct answer for you, starts with one more question: Why do you have too much fat stored in your body?
Overweight and obesity develop over time when you take in more calories than you use.
Why am I overweight? 
Two possible answers are: (1) Medical condition (2) Over Nutrition (eating too much)
How to lose weight
(1) Consult your medical doctor to identify any medical issues
There are many potential medical conditions. Medical conditions include genetics, treatments (medications for other medical conditions) as well as diseases and other medical issues. 
(2) If no medical issues: Change your lifestyle. 
How much energy your body gets from the food you eat depends on what and when you eat.
What and When You Eat
The type of food, how that food is prepared, how much of that food and how often you eat results in how much energy your body receives.
If your body receives too much energy, more energy than your body needs (or uses), you store the extra energy as fat.
If your body receives less energy than it uses (or needs) your body will not store any energy as fat.
How much food: On average, how much energy does a healthy person require?
How Food is prepared, examples: If you fry your vegetables in oil, the oil increases the energy weight of your food. Similarly, if you add refined sugar to your coffee or tea, the sugar increases the energy of that drink.
How frequently you eat and the time between meals also affects how much energy your body receives. The time between meals is usually measured in a daily period. How many times do you eat per day or per daily period is the frequency of eating.
-  https://www.nhlbi.nih.gov/health/health-topics/topics/obe/causes
-  http://www.nhs.uk/conditions/prader-willi-syndrome/Pages/Introduction.aspx
-  http://www.nhs.uk/conditions/Cushings-syndrome/Pages/Introduction.aspx
-  http://www.nhs.uk/conditions/Thyroid-under-active/Pages/Introduction.aspx
-  http://www.nhs.uk/conditions/Corticosteroid-(drugs)/Pages/Introduction.aspx
-  https://ghr.nlm.nih.gov/condition/cohen-syndrome
-  http://www.mayoclinic.org/diseases-conditions/obesity/basics/causes/con-20014834