I recently had the pleasure of presenting a talk on Keto Myths and Realities at the annual conference of the association representing Naturopaths and Herbalists in Aotearoa, Naturopaths and Medical Herbalists of New Zealand (NMHNZ).
The talk itself was great (if I do say so myself!) but some of the questions from the audience were equally great. And so, I figured Carb-Appropriate Research Review readers would also get some value from this Q&A.
Enjoy!
Could you talk about the impact of low carb on thyroid?
While true that reduced carbohydrate diets (containing less than 35% of total energy from carbohydrates) have been shown to reduce triiodothyronine (T3) levels,1 they do not affect thyroxine (T4) or thyroid-stimulating hormone (TSH) levels, nor reverse T3 levels2, 3.
A 16-week trial of a ketogenic diet for the treatment of type 2 diabetes also showed no significant effect on TSH levels,4 and no significant difference was seen between groups in TSH levels in a randomised controlled trial of ketogenic diets for the treatment of obesity and hyperlipidaemia (including 119 participants over 24 weeks).5
No statistical difference was observed in T3 uptake between a very low carbohydrate diet (VLCD) group and control, with the VLCD group exhibiting marginally higher T4 levels.1, 6
In their paper on the effects of a eucaloric ketogenic diet, Stephen Phinney and colleagues noted that despite significant reductions in T3 levels there were no concurrent effects of hypothyroidism noted and no associated reduction in oxygen uptake,1 suggesting an incomplete association between T3 levels and metabolic rate, and a differential, and not a necessarily detrimental effect of carbohydrate (and lack thereof) on the regulation of thyroid hormone levels (particularly concerning T4-T3 conversion).
Individual responses to low-carbohydrate and particularly ketogenic diets vary greatly and anyone with a medical condition should seek sound advice before embarking on a nutrition plan, but lower-carb diets are likely to be safe for thyroid function.
How much of an important factor do you think the quality of the food makes in the effectiveness of any therapeutic diet. Rather than micronutrient only comparisons. Taking into consideration the effects of food quality on the microbiome?
Food ‘quality’ is critically important to health. However, definitions of quality vary widely. Most in the clinical nutrition world determine ‘quality’ to be related to the processing of foods. Therefore, a more highly refined or ‘ultra-processed’ diet has consistently demonstrated negative outcomes, whole any diet focussed on more unrefined foods demonstrate better long-term health outcomes (assuming that it is replete in all essential nutrients). Especially concerning gut health, the higher availability of resistant starches and fibres is likely to have a more positive effect on the gut biome.
What would be an indicator for higher-carb regarding triglycerides?
Triglycerides are a key marker of cardiometabolic health and might be a stronger indicator of health outcomes than the other lipid markers.7-9 Typically, lower-carbohydrate diets have the greatest impact on triglycerides (and HbA1c),10-13 and are therefore a good ‘proxy’ for both carbohydrate intake and whether and how much it should be reduced in the diet.
There appears to be so much mixed information about a Keto diet whilst having Non-alcoholic fatty liver disease – what are your thoughts on this, please?
Non-alcoholic fatty liver disease is a metabolic disorder and thus, will be positively impacted by a low-carbohydrate or ketogenic diet.
I’m interested in knowing if Cliff still prescribes a ketogenic diet for people with adrenal fatigue, and/or for female px wanting to conceive?
There is a common misperception that low-carbohydrate or ketogenic diets are ‘bad’ for female hormone balance, but this is a misreading of the evidence. The studies used to support this idea do not show that lowered carbohydrate availability impairs hormone function but instead that drastic calorie restriction does. So, a lower-carbohydrate diet is not necessarily negative, only if (because of the satiety effects) it reduces one’s ad libitum energy intake. Similarly, for ‘adrenal fatigue’ the risk would come from energy autoregulation downwards, rather than there being a problem with carb-restriction per se.
Read: https://cliffharvey.com/do-low-carbohydrate-diets-negatively-affect-female-hormone-balance/
Watch: https://cliffharvey.com/do-low-carb-diets-affect-hormone-balance/
Read: https://cliffharvey.com/how-to-deal-with-fatigue/
I thought the loss of electrolytes was what contributed to keto flu i.e., magnesium, potassium, and salt?
Yes! The loss of electrolytes and water is the primary reason for ‘keto-flu’, along with a transiently lowered energy availability to the CNS. In a nutshell, reductions in insulin caused by a reduced carbohydrate intake signal a short-term release of increased amounts of sodium, potassium, and water.14-18 However, based on our research showing no significant difference between moderate-carb, low-carb, or keto diets in eliciting keto-flu,19 we would conclude that energy availability is the biggest impactor of the severity of these symptoms and that they are likely to be present whenever there is a large reduction in carbohydrate (even if the diet is not ketogenic).
What are the views of fruit consumption whilst on keto?
Typically, fruit is eliminated in a ketogenic diet as it can push carbohydrate intake too high and preclude nutritional ketosis. However, as we have demonstrated,19 ketosis can be achieved on widely varying intakes of carbohydrates and so, some people may be able to have some fruit and still achieve ketosis.
Are there conditions that you would not be recommending the keto diet for?
There are certain, rare genetic disorders in which ketone production is affected (particularly carnitine-palmitoyl-transferase deficiency) and people with these are typically unsuited to a ketogenic diet, however, they can be undertaken under care and with the use of medium-chain triglyceride supplementation.20, 21 There can also be ‘runaway’ ketone production in those with alcohol dependency and uncontrolled type 1 diabetes, and again, ketogenic diets should only be undertaken by clients with these conditions under care. Functionally, if a ketogenic diet drives down energy intake, resulting in a relative energy deficiency syndrome, then it is also inappropriate, and finally, most people seeking to gain appreciable amounts of muscle, or competing in sports with an extremely high volume of high-intensity activity, also benefit from higher carbohydrate intakes.
Should the key takeaway be that measuring ketones is the one thing that we should be encouraging our clients to do and then manipulating the diet from that, rather than the other way around?
Yes and no. Measuring ketones can be useful but it’s not necessary either. The simplest way to achieve ketosis and be on a ‘ketogenic’ diet is simply to avoid obligate carbohydrates. It can be useful to ‘check in’ by measuring ketone levels (with a blood-prick ketometer) to see whether the client is above 0.5 mmol/L, but the more important measures are related to the client’s health markers, measures of their desired goals, and most importantly, how they fell.
Do you think saturated fat is inflammatory though?
Not really… There are many nuances to this. While there might be some inflammatory effect of certain saturated fatty-acid chains (which are often de novo, not dietary) and there might be minor increased inflammation in saturated fat-heavy hypercaloric diets, the overall effect of saturated fat on long-term morbidity and mortality is innocuous.
Read: https://cliffharvey.com/summary-of-the-effects-of-saturated-fat-on-heart-health-mortality/
What does Cliff think of an all-meat diet?
Based on anecdotes, it appears that some people are thriving on an all-meat diet. However, the weight of evidence shows that we are omnivores and that plant foods are beneficial to health. So, I would say that for almost all people, almost all of the time, increasing vegetable intake rather than reducing it, is a better long-term strategy.
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References
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2. Ullrich IH, Peters PJ, Albrink M. Effect of low-carbohydrate diets high in either fat or protein on thyroid function, plasma insulin, glucose, and triglycerides in healthy young adults. Journal of the American College of Nutrition. 1985;4(4):451-9.
3. Fery F, Bourdoux P, Christophe J, Balasse E. Hormonal and metabolic changes induced by an isocaloric isoproteinic ketogenic diet in healthy subjects. Diabète & métabolisme. 1982;8(4):299-305.
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5. Yancy JWS, Olsen MK, Guyton JR, Bakst RP, Westman EC. A Low-Carbohydrate, Ketogenic Diet versus a Low-Fat Diet To Treat Obesity and HyperlipidemiaA Randomized, Controlled Trial. Annals of Internal Medicine. 2004;140(10):769-77.
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18. Harber MP, Schenk S, Barkan AL, Horowitz JF. Alterations in carbohydrate metabolism in response to short-term dietary carbohydrate restriction. Am J Physiol Endocrinol Metab. 2005;289(2):E306-E12.
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