Wednesday, August 28, 2013

The Nutrition Debate #138: Fruit, the 3rd Rail for Prospective Low Carb Dieters

Whenever I am asked about what foods one “cannot” eat on a Low Carb Diet, the prohibition on eating fruit is always the “3rd rail.” If you’re not familiar with this term, on electrically operated trains, there are two types of power: overhead systems and 3rd rails. Third rails run along the ground between tracks on a 2-way system. They are very high voltage and very dangerous. To touch them is to die. Like 3rd rails, life without fruit to a prospective Low Carb Dieter is similarly “fatal.”

So, some bloggers I otherwise admire and respect make an exception for fruit. They have concluded to do otherwise would be to lose the battle advocating low-carb eating before you are engaged. That’s cowardly. From my point of view, integrity demands that I speak the truth to you. I love fruit too, just as I love pasta, and rice and potatoes and bread, but I have learned that my body no longer tolerates “sugar,” especially simple sugars (mono and disaccharides). I also can’t eat any processed carbohydrates, as in virtually all packaged foods, and I can’t eat all of the starchier and sugary vegetables.

Fruit is mostly sugar. Well, it’s mostly water, but all of the macronutrient nutrition is sugar. An apple is 86% water, 3% fiber, and 11% simple sugars (0% protein and 0% fat). The sugars are 20% sucrose, 57% fructose and 23% glucose. When the sucrose breaks down to free fructose and free glucose, an apple is then 67% fructose and 33% glucose. That’s all “simple sugar”!

It’s true, an apple has some micronutrients (vitamins and minerals in the skin), and the pulp has pectin, but there are other sources for these important components in a basic “real food” diet that “cost” fewer otherwise “empty” calories. Do not use these “good” components as an excuse to eat fruit. Rationalization is just self-deception. Own up to it, my friend.

So, what do you tell someone who wants to reduce their carbohydrate intake and who loves fruit? Three common approaches are 1) don’t snack on fruit. In fact, don’t snack at all, but if you must snack, snack on fat (like a portion-controlled serving of nuts), and 2) if you must eat dessert, eat fruit for dessert instead of ice cream or pie, and 3) eat mostly berries (strawberries, raspberries, black berries and blueberries), with some fat like cream (but no added sugar!). Berries also have phytochemicals, fiber, and minerals and vitamins too. But do not ever eat grapes, or cherries, or dried fruit!

Is it possible to take a more moderate stance on the issue of fruit? Sure. As far as your blood is concerned, all carbs are equal. They will all break down to simple “sugars,” mostly glucose, some slower and some faster. If you are only mildly carbohydrate intolerant, that is, if you have been told you are “pre-diabetic,” you may be able to tolerate more “sugar” (glucose) in your diet. But be careful. This is a very slippery and treacherous slope. You could, for example, lower your carbs by a third or even two-thirds, and eat low carb, but not very low carb. Your meter will tell you what you need to know.

But this is a no-man’s land for both the patient and the clinician. Your doctor most likely adheres to the practices and “Standards of Medical Care in Diabetes,” issued by the American Diabetes Association. If you are overweight, and your A1c test, which measures the glucose on the surface of your red blood cells, is elevated, your physician will advise you that you are “at risk of diabetes.” Your doctor will then probably tell you to lose weight by eating less (on a “balanced diet”) and exercising more, but they won’t tell you to eat fewer carbohydrates, and they won’t tell you to eat less fruit. And they will definitely not tell you that if you do not change the foods you eat, that your condition is progressive and that you will inexorably become a full-blown type 2 diabetic. And that, my friend, is an irreversible diagnosis. Repeat: Irreversible.

For some reason, doctors just don’t get it, yet. The glucose in your food causes your blood sugar to rise, and if you are insulin resistant, it (the glucose) will remain circulating in your blood. The only way to lower your blood sugar, and your circulating (serum) insulin that transports the glucose, is to eat fewer carbohydrates, including but not limited to fruit. It’s that simple!

Today’s fruit is different from the fruit of yesterday in two major respects: 1) it has been hybridized to be sweeter and larger than it ever was in nature, and 2) it is no longer a seasonal treat. Due to refrigeration and world-wide air transportation, fruit is available everywhere year round. In cities today, it is available in every street corner grocery store even in the middle of winter. It is up to you to treat fruit as a treat: to eat it only occasionally, on very special occasions.
I was inspired to write this column by two recent incidents. First, I read a Q & A in “Diabetes Today” in which Dr. Richard K. Bernstein referred to “sweet fruit” as something to be eaten sparingly. He has been a type 1 for 69 years and has A1c in the 4s. He regards a 5.8 as a full-blown type 2 diabetic. You don’t usually hear the phrase “sweet fruit,” so it stuck in my mind. The other was an article, “Fruit Restriction for Type 2’s: Good or Not?” in Diabetes in Control, a digest for physicians. It compared two groups of newly diagnosed type 2s: one was told to eat fruit only two times a week and the other “given the more common conventional medicine advice to eat no more than 2 fruits a day.” After 3 months they measured A1cs, weight loss and waist size and found little difference. They concluded, “We recommended that the intake of fruit should not be restricted in patients with type 2 diabetes.” What idiots! What bleeping idiots! This is “one size fits all” advice (writ large!)  If you want to live (a long and healthy life) with diabetes, eat to your meter! And eat fruit very, very infrequently!


  1. This is so timely (for me). I just finished reading, from a low carb source, how women might benefit from fruit, especially a banana.

    My meter tells me bananas are poison.

    1. Hi Jan,
      Stefani (the Paleo for Women blogger) seems very knowledgeable, especially in the area of hypothyroidiam, various hormones, and women's health issues, but she is not advocating very low or even low carb diets for diabetics. Her emphasis in on Paleo, and she admits to advocating for low carbers (apparently w/o respect to their level of carbohydrate intolerance) to increase their level of carbohydrate consumption.

      To the extent that she does, I agree with the type of carbs she recommends. If I were not so carbohydrate intolerant, I would not hesitate to follow her advice in this respect. But I am, and you apparently are too, so we cannot.

      I addressed this subject in my column #124, "A Lamentable Confusion Between Diets." What I said there applies to us, unfortunately.

      PS: Stefani actually descirbes a banana as "a glucose bomb." How can this be good for people with IR?