The less calories you take the harder for your body to lose any weight. Also, a very low calorie diet may slow down your metabolism, making your weight loss very difficult.
When you get a chance read the top two post in this forum - it will help you understand this process better.
Let us know if you have any further questions,
Sylvia Melendez-Klinger, MS, RD, LDN, CPT - registered dietitian