Yes but it can result in strange changes to body composition if you do it wrong. So massive calorie reduction will result in weight loss but it might be the weight you don't want to lose. Changes in diet are as much about losing weight as shifting around your composition. People are also very different. Men and women are different and so are the genetics of each person. So people have to be very careful thinking that doing X will result in Y because it worked for someone else. It is why two people of the same height and weight can look so different. What matters is not the actual weight but the percentages of each. Trying to force a change early on through massive calorie reduction is what causes much of the yo yo type dieting.