Hello Stephen, can you tell us a little bit about your background and how you got interested into diet issues and became passionate about low-carb and nutritional ketosis? Was it more from a “general health” perspective or a “sports performance” perspective, or something else?

I am trained in internal medicine, and during medical school, I discovered that I could go long distances on a bicycle – but only if I ate lots of carbs while I rode.  I wondered if my patients in the intensive care unit who were not being fed felt as bad and performed as poorly as I did if I rode 200 km without eating.  After my medicine residency, I decided to take a ‘break year’ to learn more about nutrition (which was not taught in my medical school [Stanford]).  That single year became 4 years and a PhD in nutritional biochemistry.

What is your personal diet today? Do you walk the walk and talk the talk?

For nine of the last 10 years, I have eaten a moderate protein, high fat diet with less than 50 grams per day of total carbohydrates.  I eat about 3000 kcal per day, with 12-15% from protein, 80% from fat, and less than 7% from carbs.   Why 9 years out of 10?  In 2003, I adopted the above diet because of increasing weight and high blood pressure.  Within 2 weeks my blood pressure was normal off meds, and within 3 months I had lost the extra weight.  After a year on this diet, my weight and blood pressure remained normal, but my friends and family were worried that all that dietary fat would be bad for me.  So I then did a year rigorously following the DASH Diet (Dietary Approach to Stop Hypertension, promoted by the US Department of Health).  In that year of doing what I was trained to tell my patients that was the best diet for hypertension, I fully regained my hypertension and half of the excess weight I had lost.  So in May of 2005, I resumed my low carb lifestyle, lost the extra pounds, and have been weight-stable off of high blood pressure meds for 8 years.

A little bit of a historical perspective before we dig into the molecules!

Steve, you are an expert in nutritional biochemistry, so you have tools to analyse how our body functions today. We also know that today’s chemistry is the result of, well, a long, long time of tweaking by Mother Nature : depending on how you look at it, 2 billion years (first time mitochondria is included in a cell) or 2 million (first humans). Evolution has been ruthless in “choosing” adapted solutions to the issues that living organisms were facing.  What’s your take on that and how this “vision” relates to your findings in the lab?

Well, we are familiar with the idea that the agricultural revolution, 10.000 years ago, changed dramatically the way humans acquire energy (food) and expend it (exercise).

I live in California, but my ancestors were Vikings, and if I imagine where they lived in a pre-agricultural environment, what do I see? Carbohydrates such as fruit available scarcely, and only for a brief period of time during the year, maybe one month! Just try to find blueberries in Sweden in February!

So our ancestors must have been adapted to survive mostly from hunting and fishing, which means protein and fat, and whatever plants they could find, which had lots of cellulose, that we cannot really digest, and very little carbs, although plenty of micro-nutriments.

Human creativity was used to invent techniques for protein conservation, such as smoking the meat, like the pemmican that the Native Americans made (and I still do for myself). They probably have been refining the recipe over 1000’s of years and it has been a key to tribe survival. It had to be very valuable because there are traces of “trade roads” for pemmican, being traded with tobacco, flint, or even seashells.

In my book I describe the ritual of First Nations bands in Western Canada, specialized in extracting fat from a little fish called the “oolichan”. For nearly 10.000 years, they migrated every year in spring to the rivers to catch the fish, which happened to be more than 20% fat, a fat which is very much like olive oil (mono-unsaturated) and semi-solid at room temperature, hence easy to transport and trade.  So just like the Pemmican trails there were oolichan grease trails.

So this, to me, shows the importance of protein and fat in the pre-agricultural societies.

It was probably different in the tropical areas though, as the seasons are not so different and it’s easy to find plenty of fruit. But our ancestors who lived in Europe for 2 million years had to be able to thrive with very little, 5 to 10% of their total energy intake, even zero carbs for most of the time.

Which means that, contrary to us today, they were probably in “dietary ketosis” most of the time. And still able to perform much more demanding physicals activities than even today’s ultra-endurance athletes!

More in depth about low-carb

What would be your definition of low carb? I guess it may be different for every person. How can we assess it at a personal level? How do we find the sweet spot?

You are correct.  “Low carb” varies by individual tolerances.  For some people it could be 125 grams per day, and for others it is less than 30 grams per day.  At this point, finding one’s threshold of intolerance is done by trial-and-error.  How do you feel?  Is your weight stable?  Are you inappropriately hungry or have cravings?  Jeff Volek and I are currently working to validate an objective test that can give an individual ‘early warning’ if his/her carb intake is too high.  We should have an answer if that works within 12-18 months.

There is this idea that if you eat low carb, you don’t need to count calories because as you don’t have insulin spikes your body does not store whatever excess energy you put in your gut. Is this true? I understand that excess protein can trigger an insulin release, is it the same with fat? Or can I have 2500 calories from butter in one serving and not store one gram of fat (well … where would it go, I don’t know? in the toilet ?)

Most people who adopt a well-formulated low carb diet (i.e., moderate protein, high fat, resulting in nutritional ketosis) find that they reach a point of pleasant satiety before they have eaten too many calories.  In other words, on a ‘WFLCD’, it is easy to eat enough but hard to eat too much.  I don’t count calories, and my weight has stayed within a 5 pound range for the last 8 years.  If all of that 5 lb variation were due to changes in body fat, that would be 17,500 kcal of variation out of almost 9 million kcal consumed.  That translates into 0.2% accuracy in balancing intake vs expenditure.  The human gut is extremely effective in absorbing fat. It is the gut talking to the brain that determines when we stop eating, assuming we have gotten the diet composition right for our level of carbohydrate tolerance.

Do you agree with the concept of “safe carbs” or “slow energy release carbs” (whole grain, heart hearty cereals …) or you think it’s just clever lobbying from cereal manufacturers who want to stay in business ?

I would go for option 2.  As I will explain below, ketones (aka beta-hydroxybutyrate [BOHB]) are/is both a fuel and a regulatory molecule.  For many of us, health is protected if we maintain an effectively bioactive BOHB level.  For me, based upon testing my blood ketones, there are no safe grains because they suppress my ketones too much, and even modest levels of legumes and most fruits are off my ‘safe list’ for the same reason

Socio-political perspective …

What would you answer to people who say that it’s cheaper to be fed on carbs than on vegetables and fat? And that it’s unethical to eat meat?

It is also cheaper to smoke and die at age fifty than live to be ninety…

OK, that doesn’t answer the reductionist question that T. Colin Campbell’s followers love to ask. (Note : T. Colin Campbell is a famous biochemist who is a strong advocate of whole-food, vegan diet)

My wife is Asian, so my pantry contains two staples:  Thai jasmine rice (in a 50 lb bag) and high oleic safflower oil (in one gallon bottles).  The rice costs $0.41 per 1000 kcal and the oil costs $0.26 per 1000 kcal.  Assuming that a very low fat vegan eats 10% protein and 80% carbs, whereas someone on a WFLCD eats 15% protein and 80% fat, where is the price difference?  Yes, I eat some butter and olive oil as well, but they also indulge in the occasional bagel at Starbucks.  Their argument only works if they cook the numbers.

 Let’s move to … Nutritional Ketosis!

Even if there is a strong low carb community now referring to your work and of other writers like Loren Cordain, Robb Wolf, Art De Vany, Gary Taubes, Mark Sisson, and others, Nutritional Ketosis is still often considered as an « extreme » diet . Do you think that ketosis is a natural state for humans and can be kept for a long time (like weeks or months)? In your book you mention that ketosis is the first state of the human baby as the mother’s milk is mostly fat and protein? What would you be your main argument to get into Nutritional Ketosis ? Which benefits can one expect ?

Well … now there is this paper in ‘Science’ last December.   This paper will be a ‘game-changer’ going forward.  It takes extremely rigorous science and very novel findings to get a paper published in Science.  Putting it as simply as possible, these folks have demonstrated that BOHB (generated by the body when you are in Nutritional Ketosis) is a uniquely potent signaling molecule that regulates a host of different genes that in turn dramatically increases the body’s defenses against oxidative stress.  And this potent benefit is induced at blood BOHB levels characteristic of a WFLCD.

Based upon this new perspective of nutritional ketosis regulating our genes, one might expect improvements in diseases or conditions associated with oxidative stress and inflammation.  How about type-2 diabetes, coronary artery disease, most common forms of cancer, hypertension,  Alzheimer’s for starters?

What is your position on the idea that carb restriction puts the body in « survival mode» and therefore reduces the metabolism level, hence making it more difficult to lose weight? By the way, how would you measure someone’s metabolic level? Internal temperature?

If you severely restrict both carbs and calories (the so-called “very low calorie ketogenic diet’ that was popular in the 1980s), resting metabolism (resting energy expenditure, or REE) goes down about 10% and stays there as long as calories are restricted.  But as long as lean body mass is preserved, REE comes back to normal when maintenance energy intake is resumed.  Clearly, the reduction in REE was due to severely reduced energy intake, not because of reduced dietary carbs.

In my bike racers fed a weight maintaining ketogenic diet for 4 weeks, we saw no evidence of a reduction in energy use or REE.  There was a study published a year ago in JAMA (http://www.ncbi.nlm.nih.gov/pubmed/22735432) that showed a low carb maintenance diet after weight loss had the least negative effect on REE.  The problem with this study, however, was that their ‘low carb diet’ provided too much carbs and protein, so it was not ketogenic.

REE is usually measured by collecting expired air for anywhere from 15 minutes to a few days to measure how much oxygen the body is consuming.

To be continued …