Weight is not the only metric for health. How do you feel? How do your clothes fit? These are the measures that mean more. I know when I'm eating poorly and not excercizing enough by the way I feel and how my clothes fit.
The place to start is with what you take in. If you clean up your diet and stop polluting the body, it will gradually recover. Cleansing will hasten this process, but only if your diet is clean and sufficient. Starving oneself makes the diet insufficient, so the body kicks into self-preservation mode. Eating the Standard American Diet (SAD) introduces poisons, so the body can't recover.
Clean up your diet, drink lots of water and excercize 5 minutes more each day. It doesn't have to be all in one session. Time how long it takes for a brisk walk (swinging your arms) to leave you are huffing and puffing. Time it again in the evening. The next day, do 5 minutes more in the morning. The day after, do 5 minutes more morning and evening. It is amazing how much better one feels when the blood and lymph are moving.
The idea is to encourage movement of toxins out of the body. Excercise causes things to move, then you can clean the filters and make sure the exhaust pipe isn't blocked.