No of course it is not impossible. It may be harder for you to loose weight compared to others and then again it may be easier for you to loose weight compared with some others to. Focus on low intensity (i.e. power walking) for for long'ish' time durations (such as 45mins+) every day. Try and do this first thing in the morning without food as your body has dispossable energy stores for up to 30 minuites for this kind of activity and anything surplus will attack at your fat stores. Remember to have a good carb/ protein meal straight away afterwards. Don't starve yourself as your body will go into starvation mode and anything you do eat will be stored as fat. Instead drip feed your body food, ideally 5-7 small fist sized meals a day. Complex carbs in the morning and start phasing out towards mid afternoon, (such as brown rice, porridge etc). The trick is to keep your metabolism running pretty high. Try and stay away from dairy and replace fats such as butter with olive oil etc. Stop eating atleast 2 hours before bed time and limit fruit consumption to about 2 pieces a day, many people don't know but plant sugar (fructose) is fattening and anything more than 40-60g gets stored as fat. Try and eat as natural as possible, if its in a box/packet leave it alone, or atleast think twice! Remember only in the last few hundred years have we as a society had the lifestyle we have, our bodies have not yet adapted to the foods we now consume, think caveman! or cavewoman haha!
Try and make it a lifestyle change not a short term thing, set reasonable goals and stick with it. Remember it proabably took more than a few months/ years to get in the state you yourself don't like so it is going to take some time to rectify. After you have done this for lets say 6 weeks come back and we can make additional improvements but do this much for now and remember, stay positive and remember do what you always do and you'll get what you have always got.
Good luck and all the best,
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