Interview with Aitor Calero of Directo al Paladar

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Aitor Calero writes for the popular Spanish cooking and nutrition blog, Directo al Paladar ("straight to the palate").  We did a written interview a while back, and he agreed to let me post the English version on my blog.  The Spanish version is here and here.

Without further ado, here it is:


Whole Health Source, why did you choose that name for your blog and why did you decide to start a blog?

I began writing about seven yearsago because I felt I had useful information to share.  Whole Health Source was actually the name ofmy original website.  It was intended tobe a nutrition and health site, but due to my poor web development skills, itwas very amateur looking!  I took it downshortly after starting my blog because I felt the information wasoutdated.  I chose the name Whole HealthSource because it implies that health is more than just not having a disease,and that many factors converge to determine health.

What is the "state of the art" in nutrition science, what theories are right now more advanced?

I’m fairly specialized in myresearch so I’m perhaps not the best person to say what’s state of the art inthe field as a whole, but I’ll give my perspective on a few things that I findcompelling.

One of the things that I’ve foundreally gratifying is seeing the field move in the direction of studying foodsrather than specific nutrients. Essential nutrients such as minerals and vitamins are obviouslyimportant, but now that we really understand the great biological complexity ofwhole foods, it’s becoming less and less plausible that we can accuratelypredict the biological impact of a food by understanding only a few of itschemical components.  A number ofprominent researchers understand this and are moving their research in thatdirection. 

Another line of investigation that’simportant is understanding how genes and environment interact to produce healthor disease—this field will continue expanding and providing importantinsights.  There is no one-size-fits-allsolution for health. 

Gut bacteria and digestive healthhave also generated a lot of interest lately. 

There is a lot of cutting-edgeresearch going into understanding the brain mechanisms that mediate foodintake.  We’re getting to the point wherewe can predict obesity risk to some degree just by measuring cognitive traits(e.g., ability to delay gratification, impulsiveness, susceptibility toreward), or brain responses to food stimuli. Also, understanding how the energy homeostasis system in the brain isaltered during the development of obesity—this is my field.

What is the real role of physical activity? Some argue that the more you exercise the more hunger, is that correct?

I think a person would have to bepretty stubborn at this point to think that physical activity doesn’t help atall with body weight control and general health, given the state of theevidence.  For obesity, it seems to workbest as a preventive measure rather than as a treatment, and this has beenstrongly supported both by animal studies and observational studies inhumans.  It’s hard to return to true leannessonce a person is obese, no matter what strategy they use.  As we say, “an ounce of prevention is worth apound of cure”.  It is correct in ageneral sense that exercise increases hunger. However, on average it doesn’t increase hunger enough to make up for thecalories you expended, and therefore you lose fat if you’re overweight. 

There is a lot of individualvariability here.  Research has shownthat some overweight people compensate for exercise by eating more, and othersdon’t, and in some cases they even eat less than if they hadn’t exercised.   On average, exercise alone isn’t a very effectiveway to lose fat if you have a lot to lose, but it can increase theeffectiveness of dietary interventions. However, some people respond exceptionally well to exercise and can lose20, 30, 50 pounds.  Regardless of whetheror not it can turn people from fat to ripped, regular exercise is an absolutelyessential component of a healthy lifestyle.

You have debated with Gary Taubes about the role of insulin and carbs in weight control, what is right or wrong with his view?

I think Taubes has been useful inthe sense that he introduced many people to the low-carbohydrate diet, and theresearch challenging some of our conventional ideas about the health impacts ofsuch diets.  A number of studies onlow-carbohydrate diets have shown that although they’re higher in fat and meatthan most diets, when adopted by overweight or obese people they’re able tosafely cause fat loss and health improvements over periods lasting up to twoyears.  No one really knows what happensafter that.  They seem to cause more fatloss, and perhaps better metabolic improvements, than the conventional low-fatdiet for periods up to one year. Although the ability of low-carbohydrate diets (and most diets ingeneral) to cause fat loss is fairly modest in most clinical trials, someindividuals respond extremely well to it and can lose large amounts offat.  For these people, the diet can belife-changing. 

However, Taubes took this piece ofuseful information and stretched it much too far.  He ditched most of the last 70 years ofpublished research and constructed a mechanism whereby many of our modernhealth ills, particularly obesity and diabetes, are due to the ability ofcarbohydrates (particularly refined carbohydrate and sugar) to increasecirculating insulin.  It’s an extremelysimple model if you think about it: carbs -> insulin acting directly on fatcells -> obesity.  Much too simple infact, given the many roles of insulin in various tissues including the brain,not to mention all the other processes that occur with food ingestion.  Taubes has scathingly criticized seasonedresearchers for not considering his hypothesis, which he felt was correct but ignoredby researchers for non-scientific reasons (do I need to point out here thatTaubes has virtually no training or experience in the biological sciences?).  The reality is that researchers have notoverlooked the hypothesis, they have tested it in many different ways and foundthat it does not explain obesity.  As ascientist, I can’t say with 100 percent confidence that elevated insulin playsno role in obesity whatsoever, but what I can say with 99.99 percent confidenceis that no single factor will ever be able to explain common obesity.  I can also say with confidence that there aremuch more compelling explanations than excess insulin acting on fat cells, andthese are currently being pursued by many brilliant researchers.

Is fructose a problem as Dr. Robert Lustig suggests?

Humans have a very long evolutionaryhistory with fruit.  Our ancestors wereamong the first organisms to eat fruit 55 million years ago, shortly after itevolved.  Mammals likely evolved into primatesspecifically to access fruit, and our ancestors remained in trees eating fruit untilrelatively recently.  Our closest livingrelatives the chimpanzees get most of their calories from fruit, and theytherefore have a high-sugar diet.  Allhuman cultures that have access to fruit enjoy it and eat it regularly.

Studies suggest that fruit ishealthy and can even aid fat loss a little bit under certain circumstances.  However, most of the sugar people eat doesn’tcome from fruit—it comes from processed corn or refined sugar cane juice.  This poses a problem for severalreasons.  The first is that sugar andhigh-fructose corn syrup are virtually devoid of micronutrients and otherbeneficial substances, therefore they crowd out more nutritious food.  The second is that sugar increases the energydensity and palatability of foods, leading to increased meal size andeating/drinking between meals in the absence of hunger/thirst.  This contributes to obesity and all thethings that come along with it.

The third problem is that yes, inexcess refined sugar can cause metabolic problems, and this is mostly due toits fructose content.  To my knowledge,this has only ever been demonstrated with large amounts of refined sugar orfructose, and never with fruit.  Leanpeople are more resistant to the insulin resistance and other metabolicproblems that occur with fructose feeding, and this probably relates to theenergy overload already present on the liver in obesity.  It’s not clear whether or not the amount offructose most people eat today is enough to cause these problems, however Isuspect that for people eating more sugar than average, it is.  Despite its ability to cause metabolicproblems in excess, many studies have shown that fructose is no more fatteningthan other equally caloric sweet substances (such as glucose).

Is insulin the main problem? What about ghrelin, leptin and other hormones?

Insulin resistance (an inability ofinsulin to do its job properly) is definitely a central problem for health inthe 21st century.  Itcontributes to many different health conditions, particularly type IIdiabetes.  The main cause of insulinresistance is excess body fat, plain and simple, although there are many otherfactors such as exercise and diet quality that also have an impact.  To understand insulin resistance, we have tounderstand what causes excess body fat. Food intake is regulated by a “symphony” of signals that the brainreceives and uses to determine whether or not a person will eat.  Some of these signals are from sensory organsand the brain itself, while others are hormones in the circulation coming fromthe gut, body fat, the pancreas, and elsewhere. This finely tuned system is disrupted when a susceptible person isexposed to abundant, energy-dense, tasty food, in an environment that minimizesphysical activity and sleep, and promotes psychological stress.  Leptin is a key hormone that restrains foodintake in this context, but it can only go so far.  Eventually, leptin resistance develops, whichmakes it difficult to lose fat once obesity is established.

Is wheat that bad? If so, why?

Wheat is definitely bad for aboutone percent of Europeans and Americans who have celiac disease.  This alone is a major public health burdenattributable mostly to wheat.  Beyondthat one percent, I suspect that there are many other people who benefit fromavoiding it for various reasons, but that is a supposition that will requiremore research to confirm.  There areprobably many people who can eat wheat with impunity.

I think one of the most problematicaspects of wheat is that it’s used to make things that are energy-dense andtaste really good.  Flour is a substancethat can be homogenously mixed with fats, sugars, and flavorings, creatingcombinations that are virtually irresistible to the palate.  Think brownies, cookies, cake, and even a hotloaf of crusty bread.  Most people canfind room for 200 calories of chocolate cake even when they’re stuffed at theend of a meal.  Can you get that excited abouta plain potato?

A fellow named Matt Lentznerorganized something called “Gluten-Free January” last year where people gave upgluten for one month.  An epidemiologist namedDr. Janine Jagger and I composed surveys to collect anonymous information fromparticipants at the end of the month.  Wefound that almost everyone who was overweight lost several pounds, and almosteveryone with digestive problems and low energy noticed an improvement (1, 2).  There was no control group so we don’t knowhow much of the improvement was due to avoiding gluten per se, how much was due to avoiding junk food and/or reducingcarbohydrate, and how much was a placebo effect.  However, it does suggest that many peoplebenefit from giving up gluten, whatever the mechanism may be.

What about fats? Why they have been so criticized? What are the real dangerous fats?

Fats are energy dense, and saturatedfats can increase circulating cholesterol in controlled trials, therefore itwas thought that fats contribute to obesity and coronary heart disease.  I think it’s still true that fat cancontribute to obesity if it increases the energy density and palatability offood.  However, paradoxically dietary fatis compatible with body fat loss in the context of a low-carbohydrate diet, soit’s not a simple relationship.  The key inthat context is that something is being restricted.  High fat in combination with highcarbohydrate will not cause fat loss.

Saturated fat has received a lot ofblame over the years, but it’s becoming increasingly likely that it playslittle or no role in heart disease in humans, in the context of a normaldiverse diet.  That doesn’t mean a personshould put a huge amount of butter on everything or drink coconut oil, but inmoderation as part of a mixed whole food diet, I don’t see any reason to beconcerned about eating the natural fats contained in meat, dairy, eggs, andnuts, and to a lesser extent using fats like butter, unrefined coconut oil, redpalm oil, and extra virgin olive oil in cooking.

I’m not a proponent of refined seedoils (“vegetable oils”).  They’re refinedand therefore contain virtually no nutritional value, and many of them (e.g.cottonseed and soy) are by-products of other industries.  Furthermore, they tend to be high inpolyunsaturated fat and are therefore susceptible to oxidation (rancidity)during cooking, and most of them contain a lot of omega-6 and very littleomega-3, which can potentially disrupt many processes in the body (there areexceptions, such as canola oil).  If youmust use a refined seed oil for cooking, the best is probably high-oleicsunflower oil, a variety bred for low polyunsaturated and high monounsaturatedfat content.

Do we have to be worried about cholesterol? Can we control it through diet or drugs?

Cholesterol in the blood iscontained in particles called lipoproteins. Lipoproteins such as LDL (“bad” cholesterol) and HDL (“good”cholesterol) are causally related to the development of atherosclerosis(thickening and degeneration of the arteries), which increases heart attackrisk.  So yes, I think we should be worriedabout cholesterol.  The ratio of totalcholesterol to HDL cholesterol is a simple and effective indicator of risk.  For people who are interested, the Framinghamrisk calculator can give an estimate of 10-year heart attack risk based on datacollected from the Framingham study (3).

Diet and drugs do have an impact onlipoproteins.  Excess body fat increasesLDL and decreases HDL, and fat loss can reverse this to some extent.  Polyunsaturated fat lowers LDL and HDL.  Saturated fat increases LDL and HDL in trialslasting up to three months, although it’s not clear to what degree this effectpersists in the long term (in any case, it appears to have little or no impacton heart attack risk).  Dietarycholesterol has a modest ability to increase LDL and HDL.  Moderate alcohol consumption and exerciseincrease HDL and reduce heart attack risk. Smoking cigarettes lowers HDL and greatly increases heart attack risk,while smokeless tobacco does not.

Drugs such as statins lower LDL andreduce heart attack risk.  These drugs dohave side effects for some people, but they’re probably worth it in high-riskindividuals.

Your main point is that the reward and palatability plays a huge role in hunger and appetite? Why?

Food reward is the seductiveness offood—its ability to motivate you to seek it out and eat it.  Palatability is a related concept—it’s thepleasure derived from eating a food. It’s really just common sense that if a food is seductive and tastesreally good, you’re going to eat more of it, and you may even eat it betweenmeals when you aren’t hungry. 

Ourancestors lived in a world of simple foods. Even just a few hundred years ago, they didn’t have modern stoves, theydidn’t have a spice rack, they often didn’t have cooking oils, sweeteners, orsalt.  They certainly didn’t have soda,candy bars, and French fries.  They atesimply prepared whole foods, and this allowed their appetite control mechanismsto operate correctly, effortlessly matching energy intake to energy needs. 

I won’t get into the details of themechanism, but if food is highly rewarding and palatable, it modifies theseappetite control mechanisms, allowing you to eat more and accumulate more bodyfat than you would if the food were more simple.  In the US and globally we are increasinglysurrounded by energy-dense, highly rewarding and palatable foods, and food cuesin advertising that make us crave them. We eat less home-cooked food than ever before, instead outsourcing ourfood preparation to professionals who attempt to get our business by maximizingreward and palatability.

In Europe, the Dukan Diet is gaining traction as a way to lose weight, do you know it? What do you think?

The induction phase of the Dukandiet is basically a modified version of a protein-sparing modified fast(PSMF).  PSMF diets have been around fora long time—they’re basically very high protein low-calorie diets that causerapid fat loss while minimizing hunger and muscle loss due to the blandness,reduced carbohydrate, and high protein content. PSMF combines a low-fat and a low-carbohydrate diet.  PSMF diets contain very little carbohydrateor fat, and in Dukan’s case they are also quite bland.  This all contributes to the appetite suppressingeffect of the diet, facilitating fat loss. It also resets the palate to some degree, diminishing psychologicalreliance on highly rewarding/palatable foods.

That’s OK for a while as long as youcan tolerate the high protein and low calories, but obviously the diet is notnourishing enough to be a long-term solution, so it must give way to amaintenance phase.  This is where thingsbecome difficult, because most people will rapidly regain lost fat.  However, if you’re prepared to make positiveand lasting changes to your diet and lifestyle, and never return to how youwere living before, then it’s possible that you could maintain some or evenmost of the fat loss.