Can pickle juice help me lose weight. I heard it eats fats in the stomache?

Don't drink it! There is nothing healthy (quite the contrary) about drinking pickle juice straight. With some variation, pickle juice contains water, vinegar, salt, sugar. These ingredients don't "eat fats." particle size of dietary fat is decreased by the stomach's churning action. Hydrolysis of fats (triglycerides) is a complex process involving pancreatic lipase, colipase, & detergent effects of bile salts.
Not for fat. Pickle juice may work a bit like a sports drink for dedydration, according to some college football teams, but it won't do a thing for fat.