Diabetes from fruit

Mitch sat in my office, looking much the same as he had on prior visits.

At 5 ft 7 inches, he weighed a comfortable 159 lb, though he did have a small visible "paunch" above his beltline.

I had been seeing Mitch for his heart scan score of 1157 caused by low HDL of 38 mg/dl, severe small LDL (87% of total LDL), and lipoprotein (a).

Part of Mitch's therapeutic program was elimination of wheat, cornstarch, and sugars, the three most flagrant triggers of small LDL particles, and weighing his diet in favor of oils and fats to reduce Lp(a). However, Mitch somehow failed to follow our restriction on fruit, which we limit to no more than two 4 oz servings per day, preferably berries. He thought we said "Eat all the fruit you want." And so he did.

Mitch had a banana, orange, and blueberries for breakfast. For lunch, along with some tuna or soup, he'd typically have half a melon, a pear, and red grapes. For snacks, he'd have an apple or nectarine. After dinner, it wasn't unusual for Mitch to have another piece of fruit for dessert.

Up until Mitch's last visit, he'd had blood glucose levels of 100-112 mg/dl, above normal and reflecting mild insulin resistance and pre-diabetes. Today, on his unlimited fruit diet, his blood sugar: 166 mg/dl--well into diabetes territory.

I helped Mitch understand the principles of our diet better and advised him to reduce his fruit intake to no more than the 2 small servings per day, as well as sticking to our "no wheat, no cornstarch, no sugar" principles.

While fruit is certainly better than, say, a half-cup of gummy bears (84.06 g carbohydrates, 50.12 g sugars), fruit is unavoidably high in carbohydrates and sugars.

Take a look at the carbohydrate content of some common fruits:

Apple, 1 medium (2-3/4" dia)
19.06 g carbohydrate (14.34 g sugar)

Banana, 1 medium (7" to 7-7/8" long)
26.95 g carbohydrate (14.43 g sugar)

Grapes, 1 cup
27.33 g carbohydrate (23.37 g sugar)

Pear, 1 medium
25.66 g carbohydrate (16.27 g sugar)

Source: USDA Food and Nutrient Database

Fruit has many healthy components, of course, such as fiber, flavonoids, and vitamin C. But it also comes with plenty of sugar. This is especially true of modern fruit, the sort that has been cultivated, hybridized, fertilized, gassed, etc. for size and sugar content.

When you hear such conventional advice like "eat plenty of fruits and vegetables," you should hear instead: "eat plenty of vegetables. Eat a small quantity of fruit."

Comments (38) -

  • Matt Stone

    2/2/2010 2:48:37 PM |

    I agree. No matter how many times I attempt to make fruit a regular part of my diet, it always has a negative impact. At first I feel it as tooth pain. Then it seems to awaken a demon of sugar cravings.

    Getting fruit out of my diet, and more importantly - juice and refined sugar, has had the greatest impact on not only my health, but the health of my girlfriend and family members as well.  There's a huge difference between a little sugar and no sugar.

    But it has nothing to do with the carbohydrate content. Currently I'm eating at least 200 grams of starch per day, and am far healthier doing so than I was on a low-carb, high-fat diet. Have had fasting blood sugars dip all the way down to 67 on such fare.  

    One thing is for sure though. The fructose/fat combo. will give you the greatest chance to add body fat and raise your blood sugars of any other combination.  Tougher to do with fruit, but very easy to do chugging juice or soda with a mixed meal.  Like Richard J. Johnson, fructose researcher says, it is both a quantity and a speed of ingestion issue (speed of fructose ingestion that is, not of blood sugar rise, which is less significant).

  • Anne

    2/2/2010 3:16:55 PM |

    I do miss my fruits. The glucometer came in handy in helping me figure out how much fruit I could eat - 1/4 of an apple, 1-2 grapes, a couple of berries....that is it. Funny thing happened when I gave up high carb foods: vegetable started tasting sweeter.

    Dr. Richard Bernstein, who wrote Diabetes Solution, says he does not recommend any fruit and he has not eaten fruit in 40 years. He says one can get the same nutrients found in fruits from the low carb vegetables he recommends.

  • zach

    2/2/2010 3:46:48 PM |

    Fruit and honey, nature's junkfood. Although both have some redeeming qualities, unlike brownies.

  • Dr. William Davis

    2/2/2010 3:59:11 PM |

    The odd thing about fructose is that it does NOT increase blood sugar like glucose, sucrose, or more "complex" carbohydrates, but exerts a substantial delayed effect on insulin resistance, increased triglycerides, and postprandial abnormalities.

  • Simon

    2/2/2010 4:17:57 PM |

    Dr. Davis (and Matt for that matter),

    Would you suggest, if someone is fairly carbohydrate tolerant, that they actually eat there carbohydrates from properly prepared non glutenous grains or starchy vegetables rather than exceed two servings of fruit a day? Rice and quinoa etc have not gotten such a great rap, as they are not as nutritionally dense, but it seems that in light of what we know about fructose they may just be better none the less.



  • EchotechJames

    2/2/2010 5:39:07 PM |

    Interesting story, very interesting. Many of us have heard the concerns raised by the high-fructose corn syrup on heart disease and diabetes but this is the first Ive seen or at least grabbed my attention on the subject.
    Just wondering if he had any daily exercise routine to increase insulin sensitivity and ward off the blood sugar problems.
    I wholeheartedly agree with limiting fruit, although I must admit I had a half of cup of gummi bears last night (but heck, I did 2.5 hours @ 15% grade,3.5 mph yesterday) so I didnt feel like fighting the craving too much Smile
    Normally high protein to aid in recovery from strengthtraining portion of my routine but on rare occasions...
    Anyways, I would think this couldve been avoided with exercise on Mitch's part and he could get away with going bananas with the bananas.
    So what's the plan now? Give him some metformin and tell him to walk an hour a day?

    Stumbled upon this blog last night, great what Ive read so far, I think I was researching how many calories are used vs. how many are excreted in feces and your almond post came up. I bookmarked your blog.

  • Anonymous

    2/2/2010 9:38:00 PM |

    I would be curious to hear if we have any understanding of the mechanism that induced your patient's change in blood sugar. As you point out, fructose does not raise blood glucose.  If that's the case, and if wheat -- which he cut out -- does raise blood glucose, how would eating more fruit do more damage to insulin response and fasting glucose levels than the wheat that was eliminated?

    This is very interesting!


  • Diana Hsieh

    2/3/2010 2:21:40 AM |

    Hear, hear!  I used to be a fruit junkie; it seemed like a healthy way to satisfy my perpetual cravings for sugar.  When I switched to a paleo diet, my consumption of fruit gradually declined.  Now I'd prefer brussels spouts braised in cream to a banana, hands down.  Anything more than a small serving or two of berries per week seems excessive.

    Nature's junkfood, indeed!

  • Chelsea

    2/3/2010 2:42:47 AM |

    Europeans have had fruit as a part of their diet for quite a long time.  In winter they might have only had preserves or maybe no fruit at all, but when it was available, I'm sure they gorged on it and did not suffer from diabetes because of it.  Perhaps something, like Vitamin D deficiency, as you have mentioned before, could lead to his insulin resistance and inability to tolerate too much fruit?

  • Lori Miller

    2/3/2010 3:24:35 AM |

    Wow, and I thought I liked fruit. Even if you do Body for Life, which requires six hard workouts a week,that's enough carbohydrate for two days. That's about the amount of fruit I eat in a week.

  • Steve L.

    2/3/2010 4:17:24 AM |

    Fruits and vegetables; fruits and vegetables -- how I hate that ubiquitous phrase.  It's sad now many are duped simply by that reversal of words.

  • zanjabil

    2/3/2010 2:32:44 PM |

    I am an ex-fruit junkie as well. For the first time in the last 5 yrs, I'm finally losing fat. I used to eat fruit everyday 2-4 servings. Now I eat 2-4 servings a week. I pick the lower sugar ones now too.

    My husband is diabetic and I've successfully got him and our sons off of sugar(I just refused to buy any more). But I do buy fruit and honey, for the kids. But my husband continues to use both! I hope I can twist his arm into reading this post. If he would just check his blood sugar levels more consistently I'm sure he could still eat a little fruit. His favorite starch is potatoes, baked potatoes, which don't effect his sugar levels as much. I'm trying to use the potatoes to get him off the breads.

  • Bix

    2/4/2010 1:20:19 PM |

    That's a lot of fruit.

  • Peter

    2/4/2010 2:09:27 PM |

    Dr. Davis,
       I was wondering what you eat.  I understand from your blog what you don't eat, and from an interview that you are a "near-vegetarian", which you said was a preference not a principle.  So I'm wondering what you do eat.  Thanks.

  • Dr. William Davis

    2/4/2010 5:57:57 PM |

    Hi, Peter--

    Lots of vegetables, raw nuts and seeds, oils like olive, meats, eggs, occasional small servings of fruit, usually berries. Very simple.

  • Anonymous

    2/4/2010 9:27:24 PM |

    Dr. Davis, If I may ask, what types of seeds do you consume?

    I considered sunflower or pumpkin seeds, but was put off my their omega 6 profile. Would eating either type of seeds negatively affect one's w3-w6 ratio?

  • Anonymous

    2/5/2010 1:37:51 AM |

    What about avocados, tomatoes, olives and lemons?

  • Dr. William Davis

    2/5/2010 1:56:38 PM |

    All great. While I don't think that we should weigh our diets in favor of polyunsaturates (omega-6), I believe that seeds, on the whole, are beneficial, as are avocados, olives, etc.

  • Anonymous

    2/5/2010 3:46:18 PM |

    I've read in some places that a glucose spike after an intense workout is ok and that it helps build muscle.
    What's your opinion on this?

  • Nigel Kinbrum

    2/5/2010 7:25:42 PM |

    Mitch messed things up completely regarding your fruit instructions. Do you think that he may have messed up anything else in his diet?

  • Anonymous

    2/5/2010 9:08:10 PM |

    People who follow Doug Graham's 80-10-10 (carbs-fat-protein) predominantly fruitarian diet claim it's an ideal diet and that all that sugar isn't a problem as long as fat intake is very low. Is there any science to back that up?

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    3/18/2010 7:19:17 AM |

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  • Anonymous

    7/11/2010 2:33:09 AM |

    While it's interesting to read various point's of view of the percieved 'dangers of fruit' I also am noticing that there is very little in this article and it's associated comments that is anything more than opinion or worse yet, other people's opinions.

    If you were stuck on a deserted island, you would be eating whatever you could get your hands BUT you would be eating foods as nature intended them.  Coconut, seafood, wild game, and if you were lucky enough fruits, berries etc.

    Keep it natural.  If you can't find it nature, don't eat it.  Most people frown on fruit while still consuming a diet high in refined white flours, sugars, salts and more recently soy foods.  It is these foods that are destabilising your body's response to insulin spikes.

  • Anonymous

    7/14/2010 6:21:35 PM |

    Mitch did not have the problems because of the fruit, but because of the fat in the diet.
    Fat blocks insulin from working. If you eat diet high in sugars, as most of us do, you have to limit your fat to less than 10% of your calorie intake.

    I believe the answers are so simple, but we are not seeing. Just look at the animals - they are either meat eaters or plant eaters. If there is any "cross over", it is very limited, e.g. eating an insect with a plant.

    We are really not supposed to mix these foods a lot, but we all do.


    9/13/2010 7:58:55 PM |

    When you hear such conventional advice like "eat plenty of fruits and vegetables," you should hear instead: "eat plenty of vegetables. Eat a small quantity of fruit."  AND IN "IF YOU STILL EAT >10% FAT".  By now you know its the fat that makes you insulin resistant.  If you eat low fat and you still have issues, it ain't dietary diabetes.  Please get the facts correct.

  • buy jeans

    11/2/2010 8:38:59 PM |

    Mitch had a banana, orange, and blueberries for breakfast. For lunch, along with some tuna or soup, he'd typically have half a melon, a pear, and red grapes. For snacks, he'd have an apple or nectarine. After dinner, it wasn't unusual for Mitch to have another piece of fruit for dessert.

  • roberto cavali

    11/20/2010 7:58:21 AM |

    It sounds like you're creating problems yourself by trying to solve this issue instead of looking at why their is a problem in the first place.

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    11/28/2010 3:55:30 PM |

    the fruits i dont belive they are a cause for diabetes , dependes on how many we eat , excess in everything that brings benefits to the body can cause harm by excessing with it

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    1/5/2011 7:37:40 AM |

    Wow... I can't believe it that fruit can make a diabetes disease. Hmmm..thanks for the nice info.. Smile

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  • Anonymous

    1/18/2011 5:19:40 PM |

    Does anyone have an idea how much fruit or sugar that a caveman ate per year?

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    2/5/2011 5:01:07 PM |

    The diabetic patients are always wary of eating fruits as they contain sugar.They are always avoiding them...how sad that they can not derive the benefits of vitamins which they need ion the body.

  • Alex Ford

    2/22/2011 9:58:54 AM |

    People with diabetes can eat any kind of fruit, regardless of the sugar content. Everyone is encouraged to eat at least five portions of fruit and vegetables every day. Spreading the fruit you eat through the day will avoid a sudden rise in blood glucose levels.Generic Actos is the right cure if one is suffering from diabetes.
    All fruit and vegetables are extremely good for you. They are high in fibre, low in fat and packed with vitamins and minerals. Research has shown that eating more can reduce the risk of coronary heart disease, some cancers and some gut problems. So i think don't avoid fruits, and if you blame fruits then you must have to blame the rest of your diet. Well is a coke is good for your health then?lols.. What you say?

  • Exfoliating Gloves

    3/28/2011 9:19:22 PM |

    The odd thing about fructose is that it does NOT increase blood sugar like glucose, sucrose, or more "complex" carbohydrates, but exerts a substantial delayed effect on insulin resistance, increased triglycerides, and postprandial abnormalities.

  • blah blah

    2/14/2012 5:43:54 AM |

    Would some of you commenters like to go to the vegan "all fruit diet" boards and kindly comment?  You seem way more informed about the medical / dietary science behind fruit than those folks.  They''re under the impression that the reason blood sugars rise from eating fruit is b/c you''re combining it with protein/fat meals.  They say ... fat clogs insulin receptors (I''m not making this up) ... so, eating fruit with fat just causes blood sugar levels to rise and requires more insulin to get produced to get it under control.  There''s a current trend for vegans to try this Hippocrates diet or 80-10-10 diet, 80% carbs, 10% prot, 10% fat.  Eating raw is good, if it''s raw veggies, +fish proteins and fat.  But, most vegans don''t do the strict healthy stuff, instead opting for the tastiest stuff: fruit.  So, some go on these nothing-but-fruit diets, eg: 30 bananas a day.  They binge eat on fruit until they''re bloated, then wash-rinse-repeat several times a day.  Some folks have high insulin sensitivity, so they can get away with it.  But, others don''t seem to understand that just b/c it works for someone else doesn''t mean it''ll work for you.  All the sugars get burned up, then they get moody when they have a crash and have to force-feed more fruit into their system.  I just get a kick out of reading their forums, where folks seem to have this bizarre pseudo-science mentality vs. folks here that seem to have actually read and understood actual science about diet & nutrition.