Nutrition: The rest of the smoothie story

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Fresh spinach, kale or other green veggies add additional fiber, a host of nutrients and contribute minimal carbs and calories to smoothies. (Getty Images)

Sometimes it’s not what you say but what you fail to say that counts. And I sure dropped the ball when I answered Claudette’s letter about low sugar fruits in her husband’s smoothies.

“My standard advice for a healthful smoothie without excess carbs,” I wrote, “is 1 serving of fresh or frozen fruit (1/2 to 1 cup for most types of fruit), up to 1 cup of milk, milk substitute or yogurt (or a combination of milk and yogurt), and some type of added protein such as protein powder or peanut or other nut butter.”

I failed to add the other ingredients in healthful smoothies that do not raise blood sugars like fruits and fruit juices: greens! Fresh spinach, kale or other green veggies add additional fiber, a host of nutrients and contribute minimal carbs and calories. And if you’re looking to add a healthful fat to smooth out your smoothie, try a slice or two of avocado. These “green monsters” are a nutritional hit.

That settled, this came in from self-proclaimed “nerdy scientist” Phil in Corvallis, Oregon: “How does one measure the caloric content of a food? One possibility that I can image (sic) is that you dry a sample out, then burn it in an isolated container and measure how much heat (calories) is given off.”


That’s exactly how one measures the calorie content of foods, Phil. The container is called a calorimeter. The term “calorie” comes from the Latin word “calor” which means heat, since a calorie is a measure of heat.

“How do we know that our bodies actually use all the calories that we take in?” Phil continues. “Are all calories not equal in their ability to be used by our bodies? Do some calories consumed just not get processed by our digestive systems? Or do all get used or stored as fat?”

Our bodies can only do two things with calories — burn them for energy or store them either as glycogen (a limited supply of energy in the muscles) or as fat (long term storage). If your weight is going up, you are probably storing (and not using) the excess calories you eat. If your weight is going down, you are probably using up some of your stored calories.

We only get calories from carbohydrates, fat, protein and alcohol. (Alcohol is not an essential nutrient like the others, by the way.) And each of these provide varying amounts of calories. Ounce for ounce, fat produces more than double the calories of carbohydrates or protein. Alcohol is somewhere in between.

Well, Phil, out of room to answer the rest of your nerdy questions. To be continued…

Barbara Quinn is a registered dietitian nutritionist affiliated with the Community Hospital of the Monterey Peninsula. Email her at to

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