It may seem obvious to set realistic weight-loss goals. But do you really know what's realistic? Over the long term, it's smart to aim for losing 1 to 2 pounds a week. Generally to lose 1 to 2 pounds a week, you need to burn 500 to 1,000 calories more than you consume each day, through a lower calorie diet and regular physical activity.
Depending on your weight, 5% of your current weight may be a realistic goal, at least for an initial goal. If you weigh 180 pounds , that's 9 pounds. Even this level of weight loss can help lower your risk of chronic health problems, such as heart disease and type 2 diabetes.
When you're setting goals, think about both process and outcome goals. "Walk every day for 30 minutes" is an example of a process goal. "Lose 10 pounds" is an example of an outcome goal. It isn't essential that you have an outcome goal, but you should set process goals because changing your habits is a key to weight loss.
https://www.mayoclinic.org/healthy-lifestyle/weight-loss/in-depth/weight-loss/art-20047752