Some advice for those that wanna lose weight preferentially, versus wanting to build muscle and get buff.
Cardio works best. There are 3 main types of cardio almost everyone can do. Running, cycling and walking.
Running is by far the best and has full-body effects. That means that if you keep at it, you'll develop abs, proper leg muscles, basically just the upper torso and arms will get less work. It has rather dramatic effects on general health and cardiovascular health in particular, usually above what you'll get from other cardio. Can't go into too much detail without PLing dramatically.
You can focus on either health and losing weight by running at lower speeds, or muscle and explosive speed bursts by doing intervals/HIIT - at a higher risk of injury.
Cycling is your second best, and will also lose you lots of weight, has nearly similar benefits as running, but it's even more leg-centric. The biggest issue with cycling is the associated dangers, which are quite significant, i.e. cars and various accidents, many times not your fault either. Injuries tend to be severe. Keep in mind, that for outside cycling, not indoor spinning, to actually burn fat at a significant rate, at one point you'll be faced with travelling at 30-50km/h speeds with barely any protection. It's intoxicating adrenaline, but it's also a real danger.
Walking is what you do when you are too fat and out of shape to run, which is far more common than you think. Being fat puts immense pressure on joints and organs, so if you want to start with running while obese, your body will likely tell you that you're about to die, you won't be able to maintain any decent pace, and you won't last for more than 2-3 kms. If the situation is dire, it's probably best to take it slow with walks and just get to a pace where you're able to maintain a longer effort, so you burn more calories, get rid of weight, and be able to start running.
Now, about diets, which I know that many are unable to keep.
Depending on your culinary habits, your body might have been accustomed with large amounts of excess food. Letting go can be hard. Parts of your digestive system might've gotten larger, although this is somewhat controversial these days.
If you manage an active life with proper sports regimen (like 4-6 days/week, at at least a moderate intensity for like 1hr+), you might be able to lose weight even with eating normally, including sweets and other such problematic foods.
But if you do sports rarely, 1-2 times/week, and you're avoiding higher intensity exercise, you'll need to restrict your diet in rather uncomfy ways.
Best of luck!
Ideal weight is around 50kg. 
