In which Green T looks at the low carbohydrate approach to weight loss. He has personal experience of such approaches.

Low Carb world hosts a number of different varieties and diets – a Full English if you will. Paleo, Atkins, South Beach, Dukan, slow carb or even the Harcombe Diet are just a few of the myriad low carb approaches. Whilst there are nuances, indeed significant differences, between these approaches there are some areas of consensus: all apparently advocate the carbohydrate-insulin-obesity hypothesis; all therefore restrict certain types of carbohydrates for some or all of the time; all argue for fat and/or protein having a so-called “metabolic advantage” (more on this later) over carbohydrates; many advocates defend their theories with a vim and vigour that verges on religious zealotry.

The prevalence of this cluster of approaches needs to be seen in the context of the low fat, high carb governmental approach has most certainly failed the public health – at least the way it has been interpreted or implemented. Even though “low fat, high carb” is the official dietary advice in most countries around the world this has not prevented record levels of obesity, diabetes and metabolic syndrome in EVERY developed country around the world and the vast majority of developing ones too. Whilst we can argue whether people are adhering to this advice and whether food companies are interpreting this advice as intended, the fact that this approach has not led to an improvement in public health has given the oxygen necessary for alternative hypotheses to flourish. The fact that it has very “energetic” advocates and is extremely effective (at least for some people) has only advanced its cause.

Metabolic Advantage

This fancy term is simply how the nutritional scientific community describe the theory that one type of calorie (e.g. from protein) has a different, metabolically different effect than a second type of calorie (e.g. from carbohydrate). That is to say that 1000 Kcals (calories) of protein will lead to less weight gain than 1000 Kcals of carbohydrate; not all calories are created equal; a calorie is not a calorie.

This (hotly disputed) concept is at the epicentre of the Low Carb approach in part because it allows an almost unrestricted prescription of “helpful” foods; it is as useful to its proponents as “a calorie is a calorie” can be to those – soft drinks companies for example – who argue that maintaining weight is simply a case of balancing energy intake and expenditure.

Amongst those who oppose the low carb approach you will find some who doubt that this is any more successful an approach (over the long term at least) than other approaches e.g. low fat, high carb particularly as it is restrictive and, given the prevalence of “banned” foods in the world around us, exceptionally difficult to adhere to long-term. There are also those who concede that this IS an effective weight loss method albeit one achieved through greater satiety and some kind of regulatory response (i.e. you feel full more quickly or earlier – from a calorie count perspective) rather than having a metabolic advantage per se. That is to say that there is no metabolic advantage per se but that there is an effective appetite control mechanism in play.

Insofar as I am not a scientist I am not sure that I care greatly whether it is metabolic advantage or increased satiety of a dietary approach that leads to its success. I am far more concerned with what actually works and, particularly important, what works sustainably.

The Carbohydrate-Insulin-Hypothesis

This is the scientific theory that explains WHY low carb approaches work (if we indeed accept that they do). As set out by luminaries such as David Ludwig and Gary Taubes (big constellations in the Low Carb galaxy) it postulates that obesity is caused (in the main) by too much insulin action on fat cells, or viewed from the other end, that fat cells become too sensitive to the effects of insulin. This state is caused by carbohydrates which raise blood sugar too quickly (high GI or GL). It is of particular interest because it marks an alternative rationale to “Carbs In Carbs Out” (or CICO) and advocates a regulatory problem rather than an energy balance problem – which I think is getting somewhere.

Why Is This Approach So Popular?

There is a huge amount of anecdotal evidence that this approach is highly successful for a lot of people. Whether it is significant weight loss, developing an absolutely shredded physique (Google “Ted Naiman”), managing Type 2 diabetes (some Type 2s people report this approach being successful in eliminating dependence on insulin injections), eliminating common symptoms of perceived (or actual) food intolerances, many peoples’ lives have clearly been revolutionised by (or in association with) the adoption of this lifestyle. And where n=1 and

1= “me” that is all that really matters. Indeed anyone whose focus is solely personal will likely be less concerned whether any weight loss or desirable effects are due to unconscious carb reduction, increased satiety, metabolic advantage of fat / protein or other factors; it simply matters that IT WORKS and it works SUSTAINABLY. The stupendous results that some people achieve is indubitably what furnishes the advocates of the low carb approach with the sort of staunch and sometimes aggressive zeal that they display. However, a strong conviction in something that is first based on personal experience can lead to bias, unconscious or otherwise, which is a dangerous path for a scientist to be treading. It therefore pays dividend to be wary of any scientist that advocates this approach whilst successfully adopting it themselves; it’s like an inverted ad hominem. Equally that is not to say that they are wrong nor that they are biased only that their judgement *may* be clouded.

Does it Work for Everyone?

Anecdotally no. We can debate whether this is because across the entire population there is no uniform biochemistry or whether people are not doing low carb “properly”. For, any diet (by which I mean long-term way of eating rather than a short-term weight loss program) has to work in practice as well as in theory. Not eating anything would certainly lead to weight loss but even if you could sustain this it would lead to death so is not sustainable. Furthermore, in an environment where food is readily available our biochemistry would render this approach almost impossible to adhere to – it is phenomenally hard to intentionally starve ourselves. It’s an extreme example but one that I hope illustrates my point. That is we need to eat in a way that won’t have the body crying out because we are not denying it nutrients which it craves.

Is This Healthy Weight Loss and The Crunch

So you want to know my own subjective, purely anecdotal, uncontrolled and unscientific view on this i.e. what will I personally do as a result of my reading and “research” in this area? Well having strictly adhered to The Dukan Diet for 6 months I know some of the unpleasant side-effects of at least one of these approaches. Yes I lost a lot of weight very quickly – nearly 3 stone. Yes it was doable in the short-term and on some days quite easy. And yes it certainly correlated with increased mental clarity and an alleviation of some depression and anxiety symptoms. Yet the oft reported downsides: fragrant, acetone breath; constipation and passing single stools that were longer than an adult’s arm; the instigation of medium-term biochemical warfare in my stomach /brain “JUST GIVE ME SOME FUCKING BREAD / SUGAR / WINE / INSERT AS APPROPRIATE” all add up to an approach that is unsustainable for a year, let alone a lifetime. It is very difficult to effect this sort of diet without a significant reliance on animal protein and given that this is high on the suspect list of the causes of colorectal cancer, of which I have 2 generations family history, I just want a big more veg thanks. Or to frame in slightly different terms it would probably take Type 2 diabetes to make me want to eat like this. For now I will personally be looking for a different approach even if this means slower (but more sustainable) weight loss.

Further Reading

Some find him haughty and obnoxious (not me I hasten to add) others –  specifically non-scientists or those not interested in nutrition or obesity research – may find his writings esoteric to the point of impenetrability but I can highly recommend the writings of Stephan Guyenet, PhD, a “writer and science consultant with a background in neuroscience and obesity research”. The article below (and associated links) is still my go-to blog, my axiomatic foundation, for this area:

As I have alluded to above the carbohydrate-insulin hypothesis for weight loss is so interesting because it argues against CICO / energy balance as being the main factor behind weight gain / loss. As Stephan writes on his blog the majority of the obesity research community now seems to reject the simple CICO model and prefers a “third way”. That is to say an approach that is not CICO, is not carb-insulin but does think that weight gain is a problem of regulation. In future blogs I will be writing further on CICO and why I think this is an outdated paradigm and also on leptin and other hormones that are increasingly understood to play major roles in weight gain. I bet you cannot wait!

The Low Carb Lowdown:



  • For some this is THE best way to lose weight and lose it for good.
  • Particularly for those who retain water you will see a VERY fast start to a low carb diet. It’s not uncommon to lost 1/2 stone in a few days.
  • For some this diet brings other, unexpected health benefits e.g. elimination of IBS or other inflammation-linked conditions.
  • It is claimed that this way of eating can lead to increased mental acuity and clarity.


  • Even for those who lose weight easily on LC the weight piles back on even with relatively minor indiscretions and for some it IS difficult to adhere to longer term.
  • For some people the thought of low or no bread / sugar is enough to bring them out in hives.
  • A passionate advocacy base that can spill over into arrogance and even bile in some. This suggests a religious, rather than a scientific, level of fervour.
  • An approach that can lead to some “less welcome” side effects.
  • Not a great deal of documented long-term effects in the modern world although particularly Paleo advocates would argue that we evolved to eat this diet.
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Author: Tom Arundel

It’s rare for anyone to get an hour to explore their wellness goals with a trained professional. As a trained Integrative Nutrition Health Coach, I create a supportive environment that enables you to articulate and achieve your goals.

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