The body knows what it needs and knows what to do when it is introduced to something 'fake' or synthetic, whereas we were taught somewhere along the way that they help? I'm not sure about you but I am afraid of taking ibuprofen, so I cannot imagine how my body would feel about harsh prescriptions day after day after day and me thinking this is a good thing. Poor nutrition or lack of proper nutrients also causes the metabolic rate to slow. Most importantly lack of iodine in the body puts it into a complete state of disarray; virtually coming to a halt. What happens is that blood is pumped through the thyroid gland every 17 minutes and than it is distributed to the rest of the body to feed nutrients and do what it needs to do. Since the thyroid is the main provider (not storage house) of iodine for the body and in charge of the metabolic rate, it released a tiny bit of iodine into the blood so that the body can distribute and function optimally, also helping to provide iodine for the thyroid hormones; T4 and T3. That is the quick version of it, but the biologically accurate quick version.
I remember when my thyroid was slow, I was going to the gym probably 4-6 times a week and I didn't understand why I wasn't seeing results. I wasn't even partying that much or eating that much bad food. Later on I came to realize, when learning about iodine and our body's desperate need for trace minerals and whole foods, that it was probably the worse thing to do was take my body to the gym. When you have a slow metabolic rate, you cannot make it go faster by going to the gym, find out why it is slow to begin with and usually it just has to do with the nutrition levels. If you take it to the gym you are actually sweating out, whatever trace minerals you have left in the form of salt.
And if there is no proper replenishment, your thyroid continuously battles for proper nutrients, essentially panicking and fluctuating to a hyper state and eventually goitre or worse. Today, after 15 years of religiously going to the gym and sweating it out, I don't have a membership anywhere and haven't for 3+ years. And considering I don't lift weights now either, I'm amazed at how well I am doing in terms of fitness, but because my metabolism is clearly back to where it was when I was a wee thing, I am able to focus on other things I like to do. I walk 20 minutes a day and always include a wicked hill and get the muscles warm and blood pumping so that my body can properly move any toxins out and I replenish myself. At this time of year when all of the holiday parties are coming out, I am extremely thankful for knowing that I know what to do the next day after a few cupcakes...eat better!