Does this app really help

So I started the app yesterday. Put in my weight put in my weight loss goal. And it told me to consume 4040 cal per day at the end of the day I only had 2300 left. Then it told me if I ate that way I will be able to lose 25 pounds in five weeks. I threw out all the junk food in the house and bought clean healthy food meal prepped and I’m doing a low-carb diet plan. At the end of the day I wasn’t starving I was a little unsatisfied however but it was my first day. Is it really just that simple cutting the calories?