Low Carb and Low Carb High Fat diets are not likely to be embraced any time soon by mainstream medicine. That’s not because people aren’t using them or are failing. Quite the reverse. It’s more down to the fact there are plenty of actors out there, not least Big Food, Big Government and Big Medicine, who are not keen on us getting on to a bandwagon that fundamentally changes how and what we eat. If the majority of us take sugars and refined carbs out of our diets, the entire line up of products in our supermarkets, fuel stations and other outlets would change dramatically. We’d start to lose our addiction to sugar and refined carbs that are rapidly metabolised to sugar in our bodies. Big Food profits would tumble. Big Medicine would lose the truckloads of type 2 diabetics and obesity patients from whom it currently profits. You of course know all this already.

Untitled Dr Kevin Hall - Source

Keeping the anti-Low Carb machine oiled and running is big business. One of the keys is finding or creating studies that can support it. Last September you may remember we ran a story criticising a US National Institutes for Health (NIH) study headed by Dr Kevin Hall. We weren’t the only critics. The most common complaint was that the study was too short, running for only a month. Others were concerned that it only included 19 people that were not necessarily representative. We had other concerns too.

Well, at last week’s World Obesity Forum meeting in Vancouver, Kevin Hall presented on his latest study that has yet to be published. The work was supported by the Nutrition Science Initiative (NuSI), co-founded by Gary Taubes and the NIH. It’s regarded as classic, ‘gold standard’ study, because of its highly controlled nature, despite it including just 17 subjects.

Of course, it’s just a matter of time before the study is published – as the scientific journals love tightly controlled studies, even if they have little bearing on reality. The duration of the new study has been extended to 2 months but that’s still too short given what we know about metabolic adaptation and re-establishing full body/mind homeostasis.

When the study is published, probably in a matter of weeks, there will be a fanfare from the world’s media declaring a nail in the coffin for Low Carb High Fat (LCHF) diets. That’s because the findings will be misrepresented. More than this, given what we can glean from the interview with Kevin Hall last weekend (below), the findings, or their implication, may even be misunderstood by the researchers themselves. But that’s probably too early to call definitively until the paper’s out.

Below you’ll find the interview by doctor, journalist and weight loss expert, Dr Yoni Freedhoff, author of the Diet Fix at ICO 2016. Ironically, Dr Freedhoff has been a long-time proponent of working with the mind to break our habits linked to unhealthy eating patterns – these being precisely the things that are squeezed out of Hall’s latest experiment.

Watch Dr Kevin Hall’s interview at ICO 2016

Our preliminary concerns about the study

Our overall concern is that in Kevin Hall’s attempt to remove as many variables as possible, a completely unrealistic experiment has been created that bears no relationship with what overweight or obese people experience. That includes the key role our brains (and guts) play in freely choosing particular types, qualities and amounts of foods, as well as activity levels.

As part of an informal scientific forum that communicates on matters of nutritional science, Rob Verkerk pitched in some of his concerns that emerged after watching Kevin Hall’s description of the study. In his mind, the study probably raises more questions than it answers, and it shows, if nothing else, that this kind of ‘gold standard’ metabolic chamber study does not reflect what thousands are experiencing on Low Carb diets.

Questions raised about Latest NuSI/NIH metabolic ward study


  • What was the degree of insulin resistance (I.e. carbohydrate tolerance) among the 17 subjects? Individuals who were highly insulin resistant vs those who were insulin tolerant would be likely to respond very differently
  • The protocol appears designed to test the validity or otherwise of the insulin theory of obesity. It shows, if nothing else, this isn’t the primary driver of obesity (and many recognise this already)
  • The metabolic ward, isocaloric type study doesn’t allow free choice of food items (or physical activity) and therefore completely removes the brain’s involvement in food selection and appestat regulation, more likely candidates as main actors in obesity
  • The standardised dietary approach used as part of such a tightly controlled metabolic ward study implies that each kcal of each of the 3 macronutrients will exert the same effect on the body (clearly not the case) and it doesn’t take into account variability in mTOR, AMPK, sirtuins and other protein kinases controlling energy storage, utilisation and energy expenditure
  • What was the quality of the fats in the high fat/low carb study group? What was the n6:n3 ratio, saturated vs PUFA, etc?
  • What was the inflammatory profile of the test subjects both during the run-in period and the ketogenic phase?
  • How frequently were the study subjects eating? 3 times a day? Were snacks allowed between meals?
  • The curb on energy expenditure designed into the experiment would put a block on the potential benefits of the LCHF diet, and an interesting finding (that Hall indicates was unexpected - why doesn’t he talk to the LCHF clinicians??) was the increased energy expenditure outside the metabolic chamber. What might have happened if the subjects had been free to move of their own accord? More than 90 minutes of activity (in a fasted state) is generally required to burn the muscle/liver glycogen pool. Could the subjects have shifted to significantly more active lifestyles and burned even more fat once fat-adapted had they been left to their own devices (and I don’t mean iPads!)?
  • Hall appears very convinced that all the fat adaptation occurs within the first week of transition to LCHF based on 24h C-peptide measurements. Were ketone bodies (or other measures of fat oxidation) measured? Most practitioners and sports trainers I know, as well as my personal experience, would suggest 3-months as the minimum period before a degree of adaptation occurs both metabolically and in terms of the brain’s control of feeding and control of the mesolimbic reward system
  • Did any of the obesity/overweight subjects have any polymorphisms affecting their lipid metabolism, oxidation or transport?


Take home

In summary, the chances of the new Hall study being any kind of a slam dunk against the low carb movement (scientific and public) is pretty slim, although we are all familiar with the interests that will do their darndest to try!

We hope this outline goes some way to preparing you for what will happen when Dr Hall’s latest study is published.