If your basic metabolic rate is burning 1900 calories a day you should try to keep your daily calorie intake less that that ever day.
4 weeks is not enough time to lose much weight safely.
I can lose 2 or 3 lbs of winter fat a week on Optavia.
You want to keep your lean protein intake up so you don't lose lean mass/muscle.
I take about 2 months to lose 20lbs on a lean and green no carbs semi keto diet that monitors my BMI so I'm sure to lose fat not lean mass.
Great results for a flat stomach and no love handles.
After 6 weeks clothes fit better and my belt is 2 notches tighter, and I dropped from 216 to 198.
Plan to lose another 8lbs and then back to healthy lean and green, low carb meals.
It cost around $300 a month for the Optavia food, easy to follow and helps develop good cravings that will help you keep the weight off after you have reached your goals and stopped the diet.
They should of taught us this stuff in high school,
https://www.optavia.com/us/en/