I was compelled to write a long’ish comment on this post today, and thought I might as well put a copy on my own blog. Make sure to read the original post first though – it is very informative. I just dont fully agree with the conclusion…
That’s a great article. I am not really sure about your conclusion though – and I have to admit I am also not too sure what you are saying. Are you saying (1) that lowering carbs is OK for everyone, provided it is done rightly? Or are you saying (2) that “the official advice above” has not proven that some people might not adapt? I guess I would be OK with (2), but of course this does not say very much. I certainly do not agree with (1) however, or rather, I don’t agree that we have enough information to judge it.
There are two fundamental reasons why people might not be able to sufficiently adapt to a low carb diet:
- (a) there might be some genetic disposition that does not allow them to do so, or
- (b) their metabolism might have been primed to use carbs in an irreversible manner
and the statement (1) above essentially states that (a) does not exist, and for (b) it is always a matter of time, “possibly many months for those with considerable underlying metabolic derangement” as you have expressed it.
The point that I am making is that there seems to be absolutely no data as to whether all individuals (as opposed to some individuals) can adopt a low carb eating style – either from early childhood, or later on – and thrive on it. It is also unlikely that there will be hard data on this anytime soon, or even ever: as you yourself have expressed often and rightly, correlation is not causation. So any observational study will not be conclusive (and it is likely to suffer from a survivorship bias anyway: many people will drop out, and you will never know whether they would have made it eventually had they persisted). On the other hand I don’t see a 10-20 year study with a randomly selected control group (and how do you do high-carb placebos anyway?) coming for a number of reasons.
There is however some anecdotal evidence that – for some individuals – low carb is not a good idea. Thereby low carb could either be a persistent state of ketosis, or – even harder – a persistent state of gluconeogenesis. For example, Don Matesz describes why he (after 14 years!) did not longer think that Paleo / low carb was a good idea. This is n=1 of course, but so are most arguments in this sphere. And I don’t think there are many low-carbers now who can say that they have tried it for 14 years, and it works well for them.
Another thing that I am personally seeing is that in a low-carb state I am prone to palpitations – and I suppose I am not the only one, given the steady search engine referrals I get with terms such as “low carb arrhythmia”. Now my understanding of one possible mechanism for this is the following: if your body needs to resort to gluconeogenesis, then one of the stress hormone’s (cortisol?) is forcibly elevated, and this can cause palpitations. This seems to imply that persistent gluconeogenesis = persistent stress (regardless of whether this leads to palpitations) which does not seem like a good thing to me.
As an aside, you are writing
those who have struggled the most … are those who have treated low carb/paleo as a diet that is low in fat, moderate in protein, extremely low in carbohydrate, and very high in fruit and vegetables.
I would be keen to understand what you mean with this. It seems to me that you can not be “extremely low in carbs” and “very high in fruit” at the same time. Also, low fat, moderate protein, and very low carb does not seem to be possible to me: by definition those three need to add up to 100%, so at most two of them can small. Or are you talking about absolute amounts, and you are talking about an extremely calorie deficient diet here?
Anyway – this might sound more critical then it is meant to be. I am very much enjoying reading your blog, because I believe your content is great. However, whilst this post is great for the information you have given I believe that you have in this instance slightly allowed to let your convictions to allow your analytical mind, and you have drawn conclusions that might be a bit too far reaching, and that are not really supported by the data.