Dieting don't work because if it did there would be a lot of skinny people walking around instead of the 66% who are overweight! One is considered to be overweight if they weigh 10 pounds more than they should or have a Body Mass Index (BMI) greater than 27. One is considered to be obese if they weight 30 pounds more than they should or have a BMI of 30 or more.
Most diets will help you lose weight initially, but very, very few of them will help you keep it off without lifestyle changes. So what can you do? Glad you asked! Eat predominately a plant based diet - vegetables and fruits. Take your weight and divide by two and drink that many ounces of water per day. Don't eat within four hours of going to bed - if you do everything you eat goes to fat! Get your fat off the couch and start moving! Walk, joy, swim, bike etc. to get the heart pumping; do resistance training with weights. Start small and work your way upward.
By doing these type of things you can lose the weight you need to lose and keep it off without counting calories, fat grams or carbs. If you feed the body what it needs and give it the exercise that it should get, it will stay healthy, strong and useful for a lifetime.