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everyone’s gonna have you believe that fasting is gonna slow down your metabolism and it’s going to negatively affect your thyroid function well I’m here to do this video to explain the science explain the peer-reviewed studies and explain the scholarly articles that prove otherwise you see fasting doesn’t necessarily affect our thyroid well it does while we are fasting but it doesn’t affect our thyroid function overall so before I go into detail about the fasting process I have to help you understand what exactly a thyroid is see thyroid is a gland that takes in iodine from our diet and combines it with tyrosine to actually create thyroid hormones thyroid cells are the only cells that have the capability of doing this so without the thyroid we cannot create these thyroid hormones that ultimately regulate our heart rate our body temperature and other components of our metabolism so yes the thyroid is important but fasting does not negatively affect it you see we have a couple of different components when we look at the overall thyroid system and how we create thyroid hormone we have t3 t3 is the active form of thyroid that is the thyroid hormone that is actually causing the activity in your body increasing the heart rate increasing your core body temperature revving up your metabolism all of that then we have T 4 t4 is a prohormone it’s a prohormone because it encourages the production of t3 then we have thyroid stimulating hormone thyroid stimulating hormone is another precursor to even t4 TSH when it’s high means that our body is having a hard time producing enough t3 so it’s stimulating more production of TSH to actually create more thyroid but now let’s get into the fasting part because this is gonna help things make a lot more sense and here’s the cool thing most of these studies are done on longer term fasts like 7 to 10 days and they were still showing no negative effect on the thyroid so when we break it down to intermittent fasting where we’re fasting for short periods of time the results are even better so there are two studies that I actually want a reference here there’s a 2014 study in the European Journal of endocrinology and a 2008 study in the journal thyroid and they both concluded the same thing what they found in these studies is that during a fasting period after ten days of fasting there was a slight decrease in t3 during the fasting period but there was no change in t4 and no change in TSH no change in thyroid stimulating hormone so what this ultimately meant was that a multi-day fast affected the active form of thyroid while they were fasting but it didn’t actually mess up the process of creating thyroid long-term so you’re not permanently slowing down your metabolism what you are doing is temporarily reducing your thyroid that is active in the body but only during the period in which you are fasting once you break your fast your metabolism revs back up so much that it actually compensates for the slow thyroid production during your fast so net-net you end up ahead of where you were before your fasting that’s why it’s pretty powerful to actually look at the science when we’re really talking about fasting the other thing that we have to look at is that it did affect the hypothalamic pituitary thyroid axis so people that say that it affects that axis are not incorrect but it does not affect it in the way that your body cannot produce it anymore it’s only affecting the temporary production it’s no different than temporarily slowing down testosterone production only to have it come back as soon as you’re done fasting all these things don’t really matter as long as our bodies overall are in homeostasis so to help make some sense out of all of this and bring it into a practical application with intermittent fasting not just long-term fasting there was a study that was published in the Journal of Medical Sciences that was done on 42 jordanian subjects that were going through Ramadan now in case you didn’t know Ramadan ends up ultimately resulting in an intermittent fasting style structure they’re usually fasting for 12 ish or 16 hours during the day and only eating and drinking water at night so therefore we can get a pretty solid take of what 30 ish days would look like on intermittent fasting well they tested some blood markers and what they ultimately found was that although there were some changes in LDL cholesterol HDL cholesterol fasting blood glucose and a couple other general markers there were no changes no changes in thyroid hormone at all barely any change in t3 again during the time that they were fasting but no change in T for no change in thyroid stimulating hormone so this is the most practical example of an intermittent fasting lifestyle that’s been published in a scholarly article or a peer-reviewed study pretty amazing stuff so I do understand where a lot of this comes from though people tend to think that whenever we don’t eat our metabolism slows down and eventually if our caloric intake is too low our metabolism can start to slow down but that’s only if you are reducing your caloric intake for a long period of time the example being this you start intermittent fasting and after the fast you only managed to consume 1000 calories and then you fast every day so ultimately are only consuming a thousand calories every day well eventually your metabolism is going to adjust to that it’s not about what you’re not eating it’s about how much you actually are eating so if you are fasting it’s important to make sure that your caloric intake is still high enough that you’re not lowering your basal metabolic rate that’s why I’m such a fan of introducing fasting only three or four days per week especially when you’re starting out so especially for those that are concerned about slowing down their metabolism you are much more apt to increase your metabolism by going through a fasting protocol as always keep it locked in here in my channel if you have ideas for future videos or if you have any suggestions to reinforce what I just talked about today make sure to put them in the comments section below I’ll see you in the next video
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Fasting Effects on Metabolism and Thyroid- Thomas DeLauer…
The function of the thyroid gland is to take iodine, found in many foods, and convert it into thyroid hormones: thyroxine (T4) and triiodothyronine (T3.) Thyroid cells are the only cells in the body which can absorb iodine – these cells combine iodine and the amino acid tyrosine to make T3 and T4. T4 (Thyroxine) is a prohormone and is inactive – when it is converted into its active form, T3 (Triiodide Thyronine), it can exert its action on the body metabolism in each and every cell in the body.It is released into the bloodstream and is transported throughout the body where it controls metabolism (conversion of oxygen and calories to energy.)
Thyroid and Fasting:
Many people with thyroid conditions, especially hypothyroidism, are concerned about the way intermittent fasting may affect thyroid function. There is a considerable amount of research examining the impact of fasting on thyroid function, but there is relatively little information regarding the role that intermittent fasting has on the thyroid gland. Most scientific articles include experiments in which a fasting state was created by 10 days or more without food – this is clearly not the same thing as intermittent fasting and is more closely related to starvation.
Results from Longer Term Fasting Studies:
A 2014 study from the European Journal of Endocrinology and a 2008 study from the journal Thyroid both found that fasting decreases the concentration of T3 thyroid hormone while thyroxine (T4) and free T4 levels stay the same or only decrease slightly – thyroid-stimulating hormone (TSH) does not increase. Triiodothyronine (T3) is a thyroid hormone that plays vital roles in the body’s metabolic rate, heart and digestive functions, muscle control, brain development – it affects almost every physiological process in the body. Thyroxine (T4) is the main hormone secreted into the bloodstream by the thyroid gland. It plays vital roles in digestion, heart and muscle function, brain development and maintenance of bones. Thyroid-stimulating hormone (also known as thyrotropin or TSH) is a pituitary hormone that stimulates the thyroid gland to produce thyroxine (T4), and then triiodothyronine (T3) which stimulates the metabolism of almost every tissue in the body.
What the Studies Mean:
Multi-day (near starvation) fasting does change the level of the most active thyroid hormone (T3), but T4 (the precursor to T3) and the hormone used to test for thyroid function (TSH) are unchanged. So, multi-day fasting does affect the hypothalamus-pituitary-thyroid axis, just not on the hormones that affect thyroid function in the body. Fasting changes levels of thyroid-releasing hormone (TRH) and leptin, yet other values are held relatively constant over several days.
Fasting and Ramadan:
Muslims fast during the month of Ramadan – for one month, they only eat after the sun has set. They follow a pattern of intermittent fasting – fasting for 8 to 12 hours during the day followed by nourishment. A study published in the Journal of Medical Sciences evaluated the effect of Ramadan fasting on serum levels of some hormones among 42 Jordanian healthy male students. The fasting did cause a few changes in blood measurements such as blood glucose, HDL and LDL; however, most markers were unchanged. More importantly, it had no significant effect on T3, T4, or TSH levels – there were slight detectable changes in these values, but they stayed within normal limits.
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4) Impact of Ramadan Fasting on Metabolism and on Serum Levels of Some Hormones… (n.d.). Retrieved from s