Whole Fruit vs. Blended Fruit

Surely you know that smoothies are better for you than juices because they retain the fiber content of the fruit/vegetable, but have you asked yourself if a fruit smoothie has the same effect on your body as whole fruit? The answer may surprise you!

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This question came up today because a friend of mine has been on Weight Watchers for the past few months, and she was recently switched from PointsPlus to the new SmartPoints program. Under PointsPlus, most fruits and vegetables counted as zero point foods. With the updated points system, whole fruit is still zero points, but blended fruit (i.e. fruit in smoothies) has a SmartPoints value.

My friend said she and everyone else at her Weight Watchers meeting were very frustrated at this change. After all, fruit in a smoothie still technically contains the whole fruit! What gives?

If you’ve been wondering the same thing, I tried to dig up some science to explain it. It surprised me that there isn’t more evidence available documenting the effect of blending a food on glycemic index, satiety, and nutrient absorption. Here’s what I found, though:

  1. A 2007 study published in the International Journal of Obesity studied the effect of liquid meals vs. solid meals on satiety. The results showed that participants consumed on average 12% more calories per day when drinking a carbohydrate-rich drink. This suggests that drinking a blended fruit smoothie is less filling than eating a calorically equivalent portion of fruit. This is likely attributed to the fact that eating fruit takes longer than drinking it. Satiety signals are released as a hormones from the gut, and these must circulate through the bloodstream to your brain before you realize you’re full. That’s why waiting 15-20 minutes after eating a meal before deciding to eat a second helping is a good practice to adopt to avoid overeating.
  2. Chewing increases satiety. This has been documented in a study published in The British Journal of Nutrition in 2013. More chewing led to an increase in secretion of CCK in the gut (hormone that decreases appetite) and decreased secretion of ghrelin (hormone that increases appetite).
  3. Blending fruit changes the insoluble fiber contained in it. While it’s not accurate to say that blending fruit “destroys” the fiber, it does “change” it by breaking it into smaller particles. When you break the fiber compounds into smaller pieces, different things can happen, as explained in The Journal of Food Science article here. This is where the science gets sparse. Robert Lustig, MD, professor of pediatrics at University of California, suggests that blending fruit fiber has a negative effect on the glycemic index of foods. “The blades destroy the insoluble fiber, which means that the ‘gel’ that forms on the inside of the intestine has no structure. The sugar is absorbed at a maximal rate, overwhelming the liver’s capacity to metabolize the sugar, and the excess sugar is turned into liver fat which is the precursor to metabolic syndrome.” (Quote from Time magazine article April, 2015) That sounds reasonable to me, but I would much prefer a peer reviewed article cited to back that claim up!
    **If you want to completely nerd out over the food science of stuff that affects glycemic index, read this as well.

These factors combined help to explain why eating the whole, unprocessed version of a food is more filling than eating a blended, juiced, or puffed version of it. This also helps to explain why pureed or blended fruits have SmartPoints under the new Weight Watchers program. I hope that helps clear things up! Hit me up in the comments if you’d like to see more questions like this answered in the future.

References:

International Journal of Obesity (2007) 31, 1688–1695; doi:10.1038/sj.ijo.0803667; published online 19 June 2007

Zhu Y, Hsu WH & Hollis JH (2013). Increasing the number of masticatory cycles is associated with reduced appetite and altered postprandial plasma concentrations of gut hormones, insulin and glucose. British Journal of Nutrition 110: 384–390.

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6 thoughts on “Whole Fruit vs. Blended Fruit

  1. Fascinating read! I used to be on Weight Watchers when all fruit counted as points because the system was based on calories, instead of overall nutrition like fat, carbs and protein/fiber. That made it more tempting to snack on things like pre-packaged goods because the points were the same as whole foods. Then, when the points system counted fruit as 0, a person was more likely to grab a piece of fruit over say, a few cookies. Now I can see why a blended beverage can equal more, if even only a few points. It’s a bummer for the folks who need to eat in a hurry. I just think that a healthy diet really caters to slowing down, cooking at home, and eating as many whole foods as possible. But our society doesn’t really allow for that, unless you are blessed enough to have the schedule to do so.

    • Hey Korikay! Thanks for sharing your perspective and experience! Smoothies are definitely a convenient go-to for minimally processed nourishment on the run. I see both sides… Blending makes it easy to over consume fruit, but if a smoothie gets you to start eating fruits (and vegetables!) that you otherwise wouldn’t, then I think the overall benefit outweighs the slight nutritional changes made to the produce when blended.

  2. Very interesting and thank you for posting. I make my own applesauce. I slice the apples into 8ths and use the entire apple. I boil them down until they’re soft enough to run through my ricer. Would you consider this a blended fruit? Thank you!

    • Hi Tolermedia! Your applesauce is somewhere between whole and blended fruit. Boiling your apples does leech some of the vitamins out into the water, so you could consider microwaving or steaming the apple wedges to make them tender enough to run through the ricer. This will preserve as much of the nutritional value as possible. Sounds like a delicious applesauce! Thank you for the comment :)

  3. Greetings Karolina! Thank you for your comment. I’m going to consider the steaming. When boiling, I’ll sometimes use either sugar-free apple cider or sugar-free cranberry juice. When cranberries are in season, I add them to my boiling liquid at the bottom of the pot. I also use cinnamon sticks, both when boiling and in the container where I pour my apple sauce. The cranberries give it a nice color and tartness. And, as you can imagine, the cinnamon sticks are a nice complement. I’m enjoying your blog and thank you for all the information you provide!

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