pete69
04-30-2006, 09:43 PM
I posted this on the blog site as well in response to one of Dr. Eades Q&A that dealt with thyroid issues. I've seen a study say that after adaptions to ketosis (3 weeks) thyroid levels return to normal, i've never seen any data showing this for sure.
It does seem 50g of carbs a day are necessary for proper thyroid function.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1249190&dopt=Abstract
Effect of caloric restriction and dietary composition of serum T3 and reverse T3 in man.
Spaulding SW, Chopra IJ, Sherwin RS, Lyall SS.
To evaluate the effect of caloric restriction and dietary composition on circulating T3 and rT3 obese subjects were studied after 7-18 days of total fasting and while on randomized hypocaloric diets (800 kcal) in which carbohydrate content was varied to provide from 0 to 100% calories. As anticipated, total fasting resulted in a 53% reduction in serum T3 in association with reciprocal 58% increase in rT3. Subjects receiving the no-carbohydrate hypocaloric diets for two weeks demonstrated a similar 47% decline in serum T3 but there was no significant change in rT3 with time. In contrast, the same subjects receiving isocaloric diets containing at least 50 g of carbohydrate showed no significant changes in either T3 or rT3 concentration. The decline in serum T3 during the no-carbohydrate diet correlated significantly with blood glucose and ketones but there was no correlation with insulin or glucagon. We conclude that dietary carbohydrate is an important regulatory factor in T3 production in man. In contrast, rT3 concentration is not significantly affected by changes in dietary carbohydrate. Our data suggest that the rise in serum rT3 during starvation may be related to more severe caloric restriction than that caused by the 800 kcal diet.
http://www.pubmedcentral.gov/articlerender.fcgi?artid=371281
http://www.thyroidmanager.org/chapter5/5a-text.htm
(scroll down to starvation and fasting)
Composition of the diet rather than reduction in the total calorie intake seems to determine the occurrence of decreased T3 generation in peripheral tissues during food deprivation. The dietary content of carbohydrate appears to be the key ingredient since as little as 50 g glucose reverses toward normal the fast-induced changes in T3 and rT3.52 Replacement of dietary carbohydrate with fat results in changes typical of starvation.39,53 Refeeding of protein may partially improve the rate of T3 generation, but the protein may be acting as a source of glucose through gluconeogenesis.54
Any comments for those of us who are hypothyroid. Specifically, I am euthyroid stress syndrome, normal TSH, high normal t4, and very low (out of range) t3, suggesting low conversion. I also had low t3 uptake (wrong test for me) but it went along with high estrogen that I had, which might have been binding to thyroid hormone. Another test months later, with cytomel (50mcg) still showed out of range t3, despite normal estrogen. So either I have liver problems (ALT and AST were high normal, but b12 was high, so possible fatty liver) or the low carbs is inhibiting 5'diiodinase enzyme causing low t3.
It does seem 50g of carbs a day are necessary for proper thyroid function.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1249190&dopt=Abstract
Effect of caloric restriction and dietary composition of serum T3 and reverse T3 in man.
Spaulding SW, Chopra IJ, Sherwin RS, Lyall SS.
To evaluate the effect of caloric restriction and dietary composition on circulating T3 and rT3 obese subjects were studied after 7-18 days of total fasting and while on randomized hypocaloric diets (800 kcal) in which carbohydrate content was varied to provide from 0 to 100% calories. As anticipated, total fasting resulted in a 53% reduction in serum T3 in association with reciprocal 58% increase in rT3. Subjects receiving the no-carbohydrate hypocaloric diets for two weeks demonstrated a similar 47% decline in serum T3 but there was no significant change in rT3 with time. In contrast, the same subjects receiving isocaloric diets containing at least 50 g of carbohydrate showed no significant changes in either T3 or rT3 concentration. The decline in serum T3 during the no-carbohydrate diet correlated significantly with blood glucose and ketones but there was no correlation with insulin or glucagon. We conclude that dietary carbohydrate is an important regulatory factor in T3 production in man. In contrast, rT3 concentration is not significantly affected by changes in dietary carbohydrate. Our data suggest that the rise in serum rT3 during starvation may be related to more severe caloric restriction than that caused by the 800 kcal diet.
http://www.pubmedcentral.gov/articlerender.fcgi?artid=371281
http://www.thyroidmanager.org/chapter5/5a-text.htm
(scroll down to starvation and fasting)
Composition of the diet rather than reduction in the total calorie intake seems to determine the occurrence of decreased T3 generation in peripheral tissues during food deprivation. The dietary content of carbohydrate appears to be the key ingredient since as little as 50 g glucose reverses toward normal the fast-induced changes in T3 and rT3.52 Replacement of dietary carbohydrate with fat results in changes typical of starvation.39,53 Refeeding of protein may partially improve the rate of T3 generation, but the protein may be acting as a source of glucose through gluconeogenesis.54
Any comments for those of us who are hypothyroid. Specifically, I am euthyroid stress syndrome, normal TSH, high normal t4, and very low (out of range) t3, suggesting low conversion. I also had low t3 uptake (wrong test for me) but it went along with high estrogen that I had, which might have been binding to thyroid hormone. Another test months later, with cytomel (50mcg) still showed out of range t3, despite normal estrogen. So either I have liver problems (ALT and AST were high normal, but b12 was high, so possible fatty liver) or the low carbs is inhibiting 5'diiodinase enzyme causing low t3.