Losing a substantial amount of weight can take some time if done correctly and safely.
If you stick to a diet properly and get some exercise and watch the calories you intake you should be able to lose 25 lbs of weight easily in just 3 months.
Doing intermittent fasting is also good when it comes to losing weight and it's good for your health as well to clean your body out of toxins.
So in 6 months you should be able to lose 50 lbs and in 1 year you should be able to safely and easily lose 100 lbs if that is the amount of weight you're looking to lose.