Before you throw good money after bad, determine how much weight you really need to lose.
If you are only slightly overweight, go to the gym like Body will advise.
However, if you are officially carrying around enough weight to be classified as having a BMI that is "Obese" or "Morbidly Obese" then stay far away from the gym and people like Body or Opt or, for that matter, anybody who tells you to exercise to get rid of the weight. Once you are that heavy you need to remove the majority of the weight FIRST without exercise as you are only going to do serious damage to your joints and could even cause a heart attack.
You need to go on a doctor monitored weight loss program (one without stuffing yourself full of pills or using silly things like rubbing used motor oil or coffee all over your body

). Being Obese or larger is a disease just like Alcoholism and you need to recognize it for what it is. It onset may be emotional in nature and may stem from something in your childhood or any emotional crisis at some point in your life that destroyed your self esteem. Any weight loss program that has to remove huge quantities of weight may well need to be accompanied by appointment with a psychologist as well to get to the root of your emotional need to eat "comfort" foods. It will also teach you to recognize your emotional triggers as well.
Once you get within a couple of kilo of your target weight (at least the upper end of the normal range or the lower end of "Overweight", THEN it's time to start an exercise regime to rebuild your fitness in a manner that will not cause you even more medical problems.