You will lose weight when you burn more calories than you consume. Hence eating less and being more active help in losing weight

Sound eating habits keep you out of putting on weight

Try to cut down on foods high in fats and sugar

Stay motivated to lose weight

Slow weight loss is the safest and most effective.[one to one and half pound per week]

Reducing calories intake by 300 per day and increasing the physical activity to burn 200 calories per day results in weight loss of 400 Gms per week.

Regular aerobic exercise like brisk walking, jogging or swimming, is a key factor in achieving permanent weight loss and improving health

Incorporate few simple measures to burn calories effectively. Like- taking an after dinner walk, using stairs instead of escalators or elevators, parking the car farther away to have a longer walk etc

Fry or sauté foods in a non-stick cook wear with low-calorie fat.

Baking or boiling is recommended instead of frying

Hi
Well come to healthcare magic

As you told you may be fat but so soon you become tired because of less hemoglobin, I am suggesting you to do the Hemoglobin test, and in diet part you have to have fresh fruits (guava, sapota, orange, sweet lime, etc which contains vitamin c it helps to iron absorption), fresh and all types of vegetables, green leafy vegetables (drumstick leaves it contains rich in iron), try to have high fiber foods.
Avoid junk foods, chocolates, ice creams, sweets, carbonated beverages, alcohols, ghee, butter, Paneer, egg yolk.
Include: Salad, green leafy vegetables, Skimmed milk & curd, egg white, try to have more vegetables, fruits,
Exercise: Daily 30 minutes brisk walk. Some basic exercise like arm, abdominal exercise for 30 minutes. These will help to reduce your weight.