What Dusty and Crono said 100%.

The trick is to choose fibrous vegetables and low GI foods that take longer to digest so you feel fuller for longer. Make those foods dense in nutrients but lighter in calories. You could eat 1 chocolate bar a day and still be within your daily calories but you won't be happy, you'd probably get malnourished and yet still lose weight.

A simple way to cut a huge amount of calories out of your diet is the elimination of refined sugar and white, processed carbs (white breads are a big example). Favour whole grain but better favour unprocessed vegetables and other carbs (legumes).

Don't drink anything but water - for some, artificial sweeteners can trigger an insulin response. Insulin literally tells the body to store fat, process glucose, since glucose is toxic if left lying around, hence diabetes.

It's not so much losing body fat but being healthy. There are numerous ways to lose body fat, a lot which are unhealthy.

Body fat also isn't as clear cut either. Subcataneous fat, i.e under your skin, is not unhealthy. The fat that causes problems is abdominal, visceral fat that encases your organs. This is the stuff that harms you. This is what you want to worry about.

You mention you dehydrate easily? I would schedule a doctor's appointment about that and request a fasting blood sugar test, given you are concerned about body fat. If there is a problem there, it's best for your doctor to know and oversee any dietary regime. Luckily, the best medicine for those sorts of problems is good diet and exercise. It can certainly make weight loss harder if not recognised and controlled.

I hope this helps and hope you succeed