Anthony Colpo | Friday, July 1st, 2011 | Comments Off
Extract:
So What Does This All Mean?
Almost everyone assumes that low thyroid function equals excess weight gain, and that if only they could get their thyroid humming along like a Keonig-tuned Ferrari, eternal leanness is theirs for the taking.
It ain’t that simple. The human hormonal network is amazingly intricate, with an endless array of feedback loops that impact upon hormonal output and function in ways that scientists still don’t fully understand. Focusing on the level of just one or 2 hormones is somewhat myopic and often ineffective.
Researchers, for example, have observed almost no difference in various measures of energy expenditure and body composition in obese individuals with normal thyroid function and subclinical hypothyroidism (of the numerous measurements taken, only resting energy expenditure per kilogram of fat free mass was significantly different and lower, and only in the most severely hypothyroid patients)[Tagliaferri].
Which makes it less surprising to learn that treatment of obesity with thyroid hormone has delivered lacklustre results. In a 1984 report, minor weight loss was seen with treatment of subclinical hypothyroidism, but bodyweight gradually returned to pre-treatment levels at 24 months[Hoogwerf].
And lowered T3/raised rT3 does not necessarily equate to measurable differences in metabolic rate.
Numerous clinical studies have compared the effect of low-carb and high-carb diets on dietary induced thermogenesis (the increase in metabolism that occurs after a meal) and overall energy expenditure. There is either no detectable difference or a slight increase seen with higher carbohydrate meals and diets (I discuss this in detail in The Great Eades Smackdown, Part 1). However, even when differences are observed they are quite small and unlikely to have any meaningful impact upon weight loss.
Indeed, as explained in great length in The Fat Loss Bible, tightly controlled metabolic ward trials dating all the way back to 1935 repeatedly show no difference in fat-derived weight loss on isocaloric high- and low-carbohydrate diets, no matter what the caloric intake.
However, the longest lasting of these trials is around 2 months, which leaves open the possibility that the changes in thyroid levels seen on low-carb diets could cause unfavourable effects on weight status over the longer term, especially in susceptible subjects.
And remember, there’s a whole lot more to the thyroid story than just fat loss. The thyroid gland and the hormones it secretes have a profound effect on your overall health and energy levels. Any diet that produces untoward changes in thyroid hormone levels should be regarded with great caution – especially so if you are a hard training athlete whose physiology is subject to the added burden of regular and vigorous activity, or if you’ve previously displayed symptoms of low thyroid function (heightened cold intolerance, low morning temperature, clinically diagnosed thyroid dysfunction).
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Anthony Colpo is an independent researcher, physical conditioning specialist, and author of the groundbreaking books The Fat Loss Bible and The Great Cholesterol Con. For more information, visit TheFatLossBible.net or TheGreatCholesterolCon.com
