It is possible to lose weight by only reducing your calorie intake or by only increasing exercise, but research shows combining the two is a much more effective approach.
While reducing calories alone has a slight edge over exercising to lose weight, exercise can help you keep the weight off. Studies show that that those who successfully maintain their weight loss are often regular exercisers.
Combining dietary changes with exercise can also help you feel less deprived. Weight loss occurs when you take in fewer calories than you burn. By exercising, you create a greater calorie deficit for weight loss.
In order to lose 1 pound per week, you will need to create an average calorie deficit of 500 calories per day. While you can cut 500 calories from the foods you eat, a better approach may be to burn 250 extra calories and cut your food intake by 250 calories. You will likely feel less overwhelmed and more energetic with this approach. This will increase the likelihood that you will stick with your new healthy habits.