The short answer is: Maybe! Science understands weight management pretty poorly at this point, and most studies conclude that current advice about weight loss is successful over the long term for between 3% and 5% of people who follow it. So obviously, the relationship between any one lifestyle change and weight loss is complex. I am not qualified to advise you on whether adding water ex to your current routine will cause you to see a lower number on the scale.
I can, however, tell you with 100% certainty that you will build muscle mass, increase flexibility, improve your range of motion, feel stronger, and probably improve things like your blood pressure, your A1C, and your cholesterol levels with regular aquatic exercise. Those things reduce your risk factors for osteoporosis, heart disease, stroke, and other illnesses. So while I can’t tell you for sure whether you’ll change your pants size, I can tell you that you will definitely be stronger and healthier.
With low injury rates and high levels of fun and enjoyment, you’ll benefit from improved health at every size as a regular participant in aquatic exercise- and that is something to celebrate!