so I have a little story to tell. Basically it is about how the body needs certain vitamins, and stuff, and how a deficiency in such things in our diet can and will lead to a deterioration of important parts of your body's system, which can include metabolism.
So here's my story. I grew up in a vegetarian family, and so I was vegetarian. My family also taught me that doctors were corrupt and expensive, and only good for extreme life/death situation or surgery. So I never went to doctor checkups and I believe I was healthier for my vegetarian lifestyle. So now I am turning 25 years next month, and it was only now in my life that I decide to go to the doctor of my own initiative to get a general checkup. So I knew that I had some energy problem, meaning that I felt tired. But part of me believed that it was because I was lazy or I had to push myself more. And while in part that may be true, it wasn't the whole story. And so when I went to the doctor and got my blood results back, I saw I had a B12 deficiency and when I did research online on what this meant, I was shocked.
In a nutshell your body requires B12 for both your nervous system, in the continued maintenance and reparation of it, as well as all of the cells in your body requiring it to help them metabolize energy. So in the medical studies this is what they found. And there is all of interesting stuff to read on this on this website, which is geared for vegetarians/vegans, primarily because B12 is only found naturally in meat. So here I was reading this, never hearing/knowing this before, a vegetarian for practically 25 years. I luckily ate some meat substitute as what our family bought us as children (weird but true) and these had B12 in them (a small amount). But my parents never told me about B12 because they didn't know.
Here's the website: http://www.veganhealth.org/articles/vitaminb12
So basically the point of my story is that doing some very basic blood tests or general medical checkups is essential to be sure that whatever going on within you, including tiredness is not a result of some deficiency or other medical problem.
One last note, that when you get older your body has problem extracting B12 from meat, usually around 50 years old. There is also more I can say about B12, but I recommend that everyone should read the article I linked at least if not for yourself but for any vegetarians/vegans you know or will meet. Because B12 is dangerous in that it takes years for you to develop a deficiency, and so it creeps up on you sneakily, and so you may just feel tired, and not really realize what is going on. And may believe that it is part of who you are, when it may just be something as simply eating what your body requires. So if you know any vegetarians/vegans, and if you ask them about B12 and they have no idea what it is, that is a red flag.
Right now, I am taking B12 supplements, everyday, and B12 is something you can only build up again slowly, as it is stored in your Liver in large quantities, but it can only add it slowly over time. You also in fact need very little of it daily, only a tiny amount, when you have a healthy storage of it in your liver. I am also taking a general multivitamin, because I respect vitamins now, and medical knowledge about such basic points, and so I wish to not to take any chance that may compromise my experience of myself. There is more I can say, but everything I learned is there in that website. I also have a boderline thyroid problem, which having a deficiency of iodine is also a problem for vegetarians and it is explained in that website as well.
I have been humbled by this whole experience because I in a way believed that I could control my experience simply through intent, when the reality is that deficiency in food and such substances, will affect your experience, including mood, and energy levels.