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The Carb-Sharp Ratio, Part II

In an earlier post, I introduced the carb-sharp ratio, defined as [(carbohydrate gramsfiber grams) / fiber grams]. I pitched this ratio as a tool for selecting foods to help in weight loss, and I aimed it squarely at people like me, who have no medical issues around food, and no ideological commitments either (e.g., not a vegan, indifferent to GMOs, etc.). It’s designed for people who don’t like how big their belly has grown over the years, and who intend to eat differently going forward.

The carb-sharp ratio, then, has nothing to do with “healthy” eating, and everything to do with weight loss.  It’s more particularly aimed at a traditional American eater of Northwest European heritage (me), who had spent all his life eating grain products, especially wheat, at almost every meal, and who made starchy foods a big part of almost every meal.

It’s important to note that my grain-heavy diet didn’t cause me any weight gain before the age of 30, and not very much until after the age of 50.  I was born an ectomorph; my parents used to joke that they were afraid to take me to the beach as a nine-year old, lest busybodies see how my ribs stuck out, and turn them in to the authorities, on accusations of starving me.

Plus, those of my ancestors who couldn’t survive on a diet of wheat and dairy when young, all died off thousands of years ago, before they reproduced. I did fine for decades with granola or a buttered English muffin for breakfast; wheat bread sandwich for lunch; and white rice, wheat pasta, pizza or enchiladas for a dinner accompaniment. And yet and yet: by my 60s, I was carrying around quite the spare tire.  Even at the worst, you wouldn’t have thought me the least overweight if my belly was hidden from your view by a table, or if you were walking behind me—all the weight was there around my waist, a balloon held up by an inner tube. The rest of me was still the same ectomorph, more or less.

I was a perfect candidate for a book like Wheat Belly; but instead, I read Dr. Fung’s The Obesity Code. Dr. Fung is no fan of wheat, but he has a larger argument, that inspired the carb-sharp ratio.  The backstory of how I developed it may be useful in helping you decide whether to apply it to your own meal selection.

Dr. Fung or no, it’s easy to infer from the most casual acquaintance with the weight loss literature that wheat flour products, especially refined flour, might be a leading culprit in weight gain.  My first step, after getting fired up by Dr. Fung, was the easy one of trying to eliminate products with added sugar (bye bye, oh so delicious pecan granola clusters).  The second step was to look for alternatives to wheat—if only because so many wheat products seemed to contain added sugar.

If you’ve trod this path, and you have the income to purchase at a Whole Foods, or any upscale supermarket, then you know that alternatives to conventional wheat bread and wheat pasta and wheat pizza crust are in endless supply; along with alternatives to potato chips, white rice, crackers, tortillas, or muffins.  Some are positioned medically, some are positioned as organic, some are low-fat or fat-free, some are “whole grain,” yada yada.

My first act was to cut way back on any wheat, and on foods that had any added grams of sugar at all.  Lentil crackers, gluten-free pizza crust, red rice and quinoa crackers, bean chips, lentil pasta, and more—in a mood to experiment, I tossed them all into the shopping basket.  I made my own granola with no added sugar at all. As you can see from that list, I still wanted to approximate the mouth feel and the experience of the grain products I had eaten all my life.

It was only after I re-read Dr, Fung that I realized that avoidance of wheat, or obsessing about a gram or two of honey added to bread, or reflexively reaching for the “whole grain” version of anything, was largely beside the point, from the very particular perspective of maximizing weight loss.

The reasoning stems from what carbohydrates are, and what happens when the body digests them.  If you pick up any conventional discussion of healthy eating, you will read something to the effect of “carbohydrates provide a ready source of energy.”  That’s their role in nutrition: carbohydrates are easily broken down into glucose, which cells can use as fuel.

Sounds benign, eh?  You wouldn’t want to go around feeling low energy, now would you?

What conventional accounts miss is the answer to this seemingly casual question: Suppose my body doesn’t need any energy right now, or doesn’t need all the energy made available by that slice of whole grain bread?

Answer: it gets stored first as ready reserves in your liver—in your body’s checking account, to continue the financial metaphor.  Well, what if the liver’s store of ready reserves is full?  Well, most of us are careful not to leave too much money in our checking accounts.  If the balance grows too large, we transfer funds to a long-term savings vehicle.  The body does the same; except that here, long term storage means storage as fat—aka, that spare tire around your waist.  The body stores excess energy as fat. And that fact is key.

But wait: how likely is it that a pasta salad and a turkey sandwich for lunch—rather healthier a lunch than many Americans eat—would lead to excess energy in your body? For grins, check off each of the following activities you performed in the past few weeks:

  1. Guided a plow pulled by two oxen from dawn to sunset
  2. Puddled steel in a mill for a 10 hour shift
  3. Climbed a 100 foot mast with the wind at 20 knots and furled in the sail
  4. Rode horseback for twenty miles
  5. Shoveled out a ditch thirty feet long by two feet wide by three feet deep.

What? Not a single one?  Or did you maybe sit down for breakfast, then sit in your car to drive to work, then sit at your desk until sitting down for lunch, then sit in meetings after lunch, then sit in your car for the drive home, then sit down at dinner, then sit in front of the tv, and then lie down for sleep?

I submit that under that schedule, if you eat more than a dozen or two grams of excess (un-matched by fiber) carbohydrates, then you will gain weight—inexorably. The gain will be slower if you avoid added sugars, and slower still if you eat only whole grains, never refined flour; but neither of those meal choices will suffice to stop long term weight gain, much less reverse it. You’re taking in excess fuel every day.  It will make you fat.

The conventional remedial action, one I on which I prided myself for many years, was to get some vigorous exercise.  Break up all that sitting with a vigorous walk up and down hills. Take the stairs not the elevator.

Here, Dr. Fung rocked me on my heels: turns out 95% of the body’s energy budget consists of keeping the heart pumping, lungs breathing, etc.—basal metabolism. Doubling your existing exercise effort, at best, only nudges energy consumption up by 5%.  Six extra fettucine noodles at dinner, because you have a better appetite after that exercise, wipes out the effect.

You will be healthier if you take that walk; but it will not budge your weight. No matter how healthy the food you eat, if you take in extra fuel, you will gain weight over the long term.

Every day most Americans dose themselves into a state where the blood carries excess fuel.  The dose consists of the carbohydrates consumed in excess of the body’s need for energy.  Put another way, a sedentary American, who consumes anything close to the recommended daily allowance of 300 grams of carbohydrates, is taking a weight-gain pill at every meal.

Worse: many people snack between meals, and that snack is often carbohydrate-rich: bagel or muffin, crackers or chips.  I’ll leave it to Dr. Fung to explain why “no snacks, ever” is as least as important a rule for weight loss as “very little or no added sugar.”  For now, let me leave you with this image: five times every day, an office worker religiously and conscientiously takes a weight gain pill; yet they do not understand why they are unable to lose weight.

As an aside, I suspect a huge component of weight gain /loss is a function of ethnic ancestry crossed with body-type—perhaps more than is accounted for by food type, i.e., whole grains or not, or whole wheat versus brown rice.  I could eat a carb-rich diet based on refined grain flour for decades, without significant weight gain or medical issue, based on my Irish ancestry and ectomorph type.  But the laws of physiology caught up with me eventually.

Conversely, the low carb-sharp ratio diet I pursue now, with its fat- and protein-rich replacements for grain (think cheesy omelette with smoked salmon), might not be so effective in weight loss if your ancestors grew up on similar foods. Further research is needed, as we like to say in academia.

Remember, I’m neither a doctor nor a nutrition expert—just a guy blogging about a handy tool that helped him select foods for weight loss. So if you have any medical issues around food at all–why are you reading blogs instead of talking to your doctor?

Next, I consider some objections, and wind up with a few more caveats.

Why not carb count or net carb count?  Why a ratio?

 Some fraction of readers will have grown impatient: why not just count carbs, and keep that count low?  Or count so-called net carbs, carbs minus fiber?

First answer: if you ate zero carbs, you’d also eat zero fiber.  That can’t be right.

Second answer: if fiber does act as an antidote, the question becomes how best to quantify its remedial action.  Use of subtraction argues that fiber acts as a remedy 1-to-1: one gram of fiber counteracts one gram of carbs.  A ratio, as in the carb-sharp ratio, which may be a multiple of 1.0, potentially confers greater power on fiber. Or put another way, a ratio defines excess carbs in proportion to fiber, rather than in absolute terms.

A ratio has one other powerful feature. Under a net-carb accounting, all meal combinations involving carbohydrates produce an increase in net carb count, relative to eating only the lowest net carb food in the set. If net carbs are bad, and the best food provides two net carbs, then adding the second-best food, with, say, its four net carbs, gives you a total of six net carbs, and leaves you 3X worse off relative to eating only the best (lowest net) food.  Result: pressure toward a very restricted diet consisting only of the lowest net carb foods.  Fava bean flour, every meal!

Minimizing a sum or a count also implies a target of zero. Minimizing a ratio, in a context where commonly encountered ratios can be as high as 40 or 60 to 1, is much more flexible.  Mild but persistent weight gain on a diet with an overall carb-sharp ratio of 20 to 30 (me, eating oatmeal with some sweetening, whole wheat sandwiches, and white rice for dinner, still better than the ratio attained by the ordinary grain-fed American), implies steady weight loss when subsequently, the carb-sharp ratio is consistently held below 5.0, or better, near 2.5.  I don’t have to aim for a carb-sharp ratio at or under 1.0.

The ratio approach also favors food combinations in which a low ratio vegetable or bean somewhat redeems a high-ratio grain: corn chips and guacamole, rice and beans. A much wider variety of foods can be enjoyed, including some amount of whole grains (in moderation).

Last, the carb-sharp ratio, with a target ratio of 2.5 say, also limits total and net carb consumption, albeit indirectly.  Even on my new regime, I find it hard to achieve the recommended daily amount of fiber (about 25 grams).  If I can only pull together 20 grams of fiber in a day, then with a target ratio of 2.5 (more aggressive than needed for weight stabilization, but appropriate for a period of substantial belly shrinking), than my total carb count is limited to 50, and my net carb count is limited to 30.  For context, 300 grams of carbs per day is the recommended allowance—which would be a carb-sharp ratio of 15-to-1, on 20 grams of fiber.

In sum, although the carb-sharp ratio has a different formulation than the net-carb approach, anchored more directly in the antidote power of fiber, it leads to a similar end: a drastic restriction in carb consumption—without the distraction of thinking you must come as close to zero as possible, or the incredibly restricted (and therefore unsustainable) diet to which the zero target too often leads.

I should point out here that I really like to eat—everything except rabbit food. Mealtimes are among my favorite parts of the day.  But I do want to shrink my belly, and the carb-sharp ratio was forged from these twin imperatives: eat a variety of delicious food, and shrink the belly.


Constraining the day’s carb-sharp ratio to less than 5.0 does not automatically imply a high fat, low carb diet (HFLC), especially if you are a vegan, or have a high tolerance for rabbit food (aka salad). But if you are a carnivorous, salt-tolerant person like me, who loves to eat food with rich flavor, then restraining your carb-sharp ratio to a low value probably does, initially, lead to an HFLC style diet. However, you don’t target a certain amount of fat, and you don’t target some level of protein, as in prescriptive diets.  Rather, you eat whole foods that taste good, mostly not grains, that keep your carb-sharp ratio low, and that satisfy you.  It’s that latter point that drove a rabbit-food hater like me to what in practice looks rather like a HFLC diet. I enjoy my meals as much or more as before.

One of the most chilling parts of Dr. Fung’s book is his physiological explanation of why repeated dieting, on the conventional plan of calorie restriction, ultimately makes it harder and harder to lose weight by altering what you eat.

Although Dr. Fung is appropriately cautious regarding this next point, it’s a straightforward extrapolation from the evidence he marshals: I surmise that restricting fat intake makes it harder to lose the weight stored up from decades of excess fuel intake. To lose weight the body has to consume the fat cells it had stored around the waist.  It has to transfer money out of long-term savings into the checking account, and then spend down that checking account far enough to trigger another transfer from savings, day after day. If your paycheck is large enough (i.e., if your carb consumption continues at a level equal to or higher than your energy budget), then the checking account never gets empty, and no transfers are made from savings.  You do not lose weight.

Dropping the metaphor and returning to physiology: if there isn’t enough carb fuel in the body for its needs, and the liver’s ready reserves are also low, the body (reluctantly) will fall back to the more difficult task of extracting fuel from fat, which is harder work and a last resort. To do this it converts stored fat to ketones, fuel which can be used to make the energy cells need.

Now imagine the person eating a low fat diet, but otherwise maintaining high, even levels of energy by consuming sufficient carbohydrates.  Result: no practice making ketones.  No ready, smooth switch over to “eh, time to use some of the fat I stored up long ago for just this occasion.”

Now compare the person eating an HFLC diet, and being very careful to maintain large gaps between meals (no snacking, ever; and grazing is the spawn of hell).  By 3pm, and 10pm, on a conventional lunch and dinner schedule, the body has exhausted the easy energy it could extract from the few carbs it was given; the more so, if a big chunk consisted of fiber.  But there’s plenty of potential energy nearby—the fat that was consumed at lunch and dinner. All the body has to do is trigger the more difficult task of ketone production. Result: practice making ketones every day, because the body has not been deprived of the fat which it needs for practice.  And when the daily dose of fat also runs out, a seamless switch over to burning fat stored around the waist, and laid down years ago, becomes more likely.

Conversely, a low fat, high carb diet—the conventional dietary recommendation over the past few decades—is like having an ample paycheck, so that you never run out of funds before payday. No prudent citizen dumps money out of long term savings into the checking account unless forced to by circumstance.  No human body extracts fat from long term storage unless required. It has to run out of energy first, and it helps a great deal to have daily practice in running out of cheap, easy carb energy. Then the body knows what to do.

You can’t lose weight unless you spend some hours of every day hungry, in the specific physiological sense of having no cheap carb energy available.

The very curious fact, and the saving grace of following the HFLC path, is that the subjective experience of physiological hunger changes. On the low fat, high carb path, with snacks, you top off your body’s (carb) fuel tank every day, multiple times per day. There’s never a need to tap long term stores, or for any form of ketosis. Maybe the body forgets how to do it, or gets sluggish about it. Then one day, lunch gets delayed, or you didn’t eat much of it because it didn’t taste good. Later that afternoon, when physiological hunger strikes for the first time in eons, you feel awful.  A person of my age and provenance would joke about having “low blood sugar.” You want to grab for a snack RIGHT NOW. You are jittery. You are crashing.  It’s aversive.  You snarl at the waitress—why is my food taking so long? BRING ME MY CARBS!!

But on the HFLC diet, the subjective experience is very different.  On this regime, you experience physiological hunger—aka, lack of readily available carb fuel—several times per day, every day. Your body becomes accustomed to it.  Like the smooth transition from electric propulsion to gasoline propulsion in a well-designed plug-in hybrid car, your body simply says “carbs needle on empty? OK, let’s switch over to ketosis.”

And later that night, when even the fat you ate that day is all gone, your body says, “OK, time to break into long term stores.”  And the spare tire shrinks a little bit more.

Caveats and Future Research

Remember, I’m just a retired professor blogging about what interests me.  I have no authority in this area.

Next, the carb-sharp ratio makes the simplifying assumption that all (fiber-free) carbs are created equal, and likewise, that fiber is fiber is fiber (it takes no account of soluble versus insoluble). Well, the old mantra that a calorie is a calorie is a calorie didn’t work out too well, did it? Calories obtained from high-fructose corn syrup are not created equal–they really are worse.

Accordingly, it’s entirely possible that some carbs are worse than others (wheat being the leading candidate for censure).  The exact chemical composition of the carbohydrates in wheat may preferentially lead to insulin spikes, or otherwise frustrate efforts to burn stored fat rather than add to it.

Likewise, it’s not clear whether adding stand-alone fiber has the beneficial effect that the resulting lowered carb-sharp ratio suggests it should.  I’m fond of a low carb tortilla made mostly from oat bran and soy flour, with some wheat, and a great carb-sharp ratio of 1.375. But does the oat bran protect against the wheat, as that ratio suggests, or does this tortilla have the same effect as eating exactly that much wheat flour on its own, with no amelioration?

On similar reasoning, anything made of flour, particularly if finely milled, may be worse than the un-ground version of the same grain or legume.  The problem would be not so much the grain but the grind. Oat bran would only protect against the rest of the oat kernel when consumed as an intact package. Mixing it in with wheat kernels has no preventative effect, because the wheat kernel isn’t encapsulated within the oat bran.

The analogy here is to melting chocolate.  Even if the average temperature comes in below the scorch point, if you turn away and exceed that temperature for even a few seconds, the chocolate gets a scorched taste that won’t go away.  Similarly, no matter what the overall carb sharp ratio, it may be that consuming a portion of wheat flour, above some threshold amount, screws up the process of ketone production / transfer from long term storage, maybe for the whole day.  Which means no weight loss that day, and maybe no ongoing weight loss at all, if you fall off the wagon that way for several days a week.

Future research will be required …

Comments welcome as always. And please do read Dr. Fung’s book.

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