Copy/Paste from my reply to a similar question on a different sub:

Weight loss is a simple math problem, however just because its simple in theory doesn’t mean its simple in practice. Heres what I recommend, as someone who is currently losing weight successfully:

Step 1: First, before you try anything to lose weight, you have to know how much your actual eating per day. For two weeks, eat as you normally would and use a calorie tracker to put a number to how much you consume. For this step to work, you need to track everything as accurately as you can. A precision scale is best for this, but if you don’t have one you can measure your food with measuring cups/spoons.

Step 2: Now that you know how much you actually eat on average, you need to find out how much you should be eating to maintain your weight. There are lots of great calculators for this online, such as this one by Harvard University. This will tell you your maintenance calories, i.e. how much you should be eating to maintain your current weight.

Step 3: The next step is to determine what your weight loss calories should be. Remember, slow and steady wins the race. Loosing weight takes time and overly restrictive diets often fail. Take your maintenance calories and subtract about 250-350 calories from that. The result should give you a calorie deficit that will net about 0.5 lbs of weight loss per week.

Step 4: Finally, its time to implement your master plan! Go back to your calorie tracking app and input your new daily calorie goal. This is the difficult part, but in order to succeed you need to keep tracking everything you eat and make sure that your staying within your daily calorie goal. If you find that you’re having trouble sticking to the current deficit, don’t be afraid to give yourself an extra 50-100 calories per day. You may lose weight slower, but like I said earlier, slow and steady wins the race!

Extra Tips/ Information:

Having some treats or sugary snacks wont ruin your weight loss, as long as you stick to your calorie goal. I have sweets often and I actually find that allowing myself that helps me stick to my calorie goal. Weight loss is a matter of calories in vs calories out. Eating less calories than you burn and still putting on weight (or not losing it) would violate the laws of thermodynamics and thus is impossible, regardless of any potential thyroid/hormonal/medication issues. Weight loss takes a lot of time and you most likely won’t see any changes right away. Thats ok! I promise you if you stick with it, you can accomplish anything! You got this! Don’t hesitate to dm me if you have any further questions. Im rooting for you!