Taking Thyroid And Metabolism Meds Since May Last Year, L

Taking thyroid and metabolism meds since May last year, l have gained 20 pounds on a plant base diet recommended by doctors, eating 1500-1800 calories per day, & eat very little good "fats", very frustrated so guess back to Akins, what do you think? Doctors recommendation of plants base healthy eating with no protein animal fats, truthfully has turned out to be a crock of crap when I just keep gaining. Am 62 years old. Alarming gaining weight. Even on salads. Meds aren't working, plants based healthy eating isn't working; exercise with walking, stretching, stationary bike, not working. Am 120 lbs. overweight, have been on Weight Watchers and Atkins for 2 years, losing and gaining the same 40 pounds up and down, but not the "old fat". Cannot get rid of the visceral belly fat. Deeply concerned. Doctors have no answers, been to 3 of them, all suggesting everything they can think of like celiac, food allergies, etc. Was tested for those and nothing....trying hard to avoid bariatric surgery as I think it's just a band aid on a deeper problem. I am not a binge or emotional eater. So I don't get this. Drink 108 oz. of water per day with lemon. Was told I have no metabolism, meds don't work obviously. Thanks, sorry am so long-winded. FORGET IT, I AM UNEMPLOYED AND HAVE NO MONEY, THANKS ANYWAY!