There are a number of reasons a person may struggle to lose weight. Firstly, you may be eating too many calories, resulting in the unused calories being converted into fat cells if not utilized as energy.
Another is your plan may not be tailored specifically to your goal. There’s no point in eating more calories only to try and outrun your diet. Leave that for the genetically gifted 5% of the population.
You also could find yourself under eating which in turn can slow down your metabolism. If you undereat, your body will go into survival mode and will refuse to release fat cells as it is unsure when the next meal is coming.
And finally, you may have a history of YOYO dieting which has suppressed your metabolism and trained your body to only accept low calories. This can be reversed over time by slowly adding calories weekly to your diet. Metabolism follows food, so a simple increase in calories over months can reverse this.
Start focusing more on intensity, consistency and have the patience to achieve the results you are after as it will not happen overnight.