Diet and exercise both play a vital role in your weight loss journey. For effective weight loss, it is important to follow both. But in the beginning, you need to start slow. If you have started dieting, particularly those which require you to cut down too many calories, wait for a week or two before kick-starting any workout routine. A restrictive diet or too many changes in it can make you weak and tired. Give yourself some time to adjust to the changes before starting your workout routine. Doing both together may increase the risk of injury and you might also lose motivation.