Ask a Scientist: Is Juice Bad For Me?

The Scientist: Kristen Kirkpatrick, R.D., YouBeauty Nutrition Advisor.

The Answer: In a word: yes.Juice is basically fruit stripped of its fiber content, so what remains is a ton of sugar: 20-30 grams in an eight-ounce serving, depending on the type of juice. That’s on par with a regular soda.

Drinking that much sugar causes a big spike in your blood sugar and insulin levels, which then drop to below their original levels, bringing on the inevitable crash. Fiber—which is found in the peel and body of a fruit—takes a lot of time to digest, and sugar absorption slows along with it, giving your body enough time to process it properly. When the fiber is absent, you absorb the sugar very quickly, so it rushes into your bloodstream. What your body doesn’t use right away gets stored as fat.

You still get the vitamins and minerals, so it’s not a complete wash, but it is far worse for you than eating a piece of fruit. Grape and tomato juice, for example, have twice the sugar as the same amount of their chewable progenitors. Fruit juices generally have several times more sugar than vegetable juices.

It’s amazing (and kind of gross) how many calories you can gulp down without realizing it. A cup of blueberries, about 80 calories, could take five or 10 minutes to eat. But you could easily down a cup of blueberry juice, 130-160 calories, in 30 seconds.

A glass of juice a day won’t ruin your health. But if you’re craving the flavor of a ripe, crisp apple, go for the real McCoy (like a real McIntosh).


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    The fiber in the fruits seldom is sufficient as a % of the calories to really stop the glycation of the fructose that is higher than the glucose in the fruit. So the high sugar fruits STILL present a problem with significantly more sugar than fiber and screw up the blood sugars anyway. Also, fructose does NOT go for energy but it does get turned into blood fats like triglycerides and LDL particles that cause heart disease. Fructose NEVER is converted to body fat. It only contributes to heart disease. Other sugars in fruits eaten above energy needs like glucose, lactose, starch all get turned into fat when they are eaten in quantities greater than the day’s energy needs. This is why weight loss plans that cut back on carbs have been more successful for the last 100 years for weight loss. Low Fat High Carb diets like WW (and the ADA Diabetic Diet plan without supplied food, just advice) that supply your purchased food for you can succeed providing you stick to them religiously and you can lose 1-2 pounds a month while paying for the meetings and official pre-packaged food. But High Fat, Low Carb diets work far better for weight loss over and over and over and over.