Are smoothies actually healthy?
August 31, 2017 1:12 AM   Subscribe

What's the scientific consensus? - I'm assuming smoothies made of just whole fruit, no added juice.

I understand that fruit juices aren't considered particularly healthy any more, due to their sugar content. And the sugar is absorbed quite quickly, unlike with fresh fruit. So I can see that smoothies made with a lot of juice might not be that healthy. But what if they were just made with fruit (and maybe water/plant milk)? How would that compare to quickly eating the fruit itself? (I'm saying "quickly" because I know one of the differences between smoothie and whole fruit is how quickly you can consume smoothies.) Say if you had a smoothie made of whole oranges (minus pips), whole apples (minus core), whole grapes, and whole raspberries. (Those are all quite juicy fruits so you might not need to add water.) Would that be healthy, or would something about the actual process of smoothie-making make it dubious health-wise? Does it also depend whether you have a high-speed blender, with high-speed blenders making them more unhealthy?
posted by tangerine_poppies to Science & Nature (11 answers total) 5 users marked this as a favorite
One thing that happens is that blending the fruit does some of the work of digestion for you, meaning that basically all of the calories (which in fruit is almost all sugar calories) are more available to your body. Eating the fruit normally means that a certain percentage of calories may never become available as the structure containing those sugars might never completely break down as the fruit makes its way through your digestive system and out the other end.

However, this also means that you will probably get more of the available vitamins from a smoothie than you would eating the same amount of fruit the regular way.

There are lots of different aspects of "healthy" - someone who needed to lose weight to bring down their blood pressure, or someone with diabetes, might not need the extra sugar they'd get with a smoothie, while someone else might have digestion issues or other reasons that make the easier availability of vitamins and sugars a good thing.

Just keep track of what is going in them - a colleague was really confused why he was gaining weight recently, and when I asked him about his smoothies and helped him do the math it turned out he was chugging almost 2k calories of fruit, yogurt, and peanut butter before 9 am every day all the while thinking it was a light, healthy breakfast!
posted by cilantro at 2:02 AM on August 31, 2017 [13 favorites]

The difference between whole fruit smoothies and no-sugar-added juice smoothies is negligible.
posted by DarlingBri at 2:15 AM on August 31, 2017 [2 favorites]

From a caloric standpoint they can be pretty unhealthy, in the sense that it's easy to get way more calories into your body than it feels like you're ingesting. Of course, if you need to put on some weight then this can be a benefit; but for those who want to lose weight, they can be a bit of a trap. Also, as mentioned above, those calories are going to involve a lot of sugar. And to make them actually be filling, to make them feel like a meal, they need to be pretty huge. So to me (who is trying to lose weight, if anything) they're in the "perfectly fine once in a while, but not every day" camp.
posted by Anticipation Of A New Lover's Arrival, The at 5:02 AM on August 31, 2017

If you a small one at home with just a cup of berries, some greens, protein powder, and water, they can be very light compared to ones from like Jamba Juice.
posted by cakebatter at 5:14 AM on August 31, 2017 [2 favorites]

You have to define healthy to really make an assessment here. Like all things (except perhaps a number of raw vegetables which are healthy for the vast majority of us), health is very much an individual thing and whether it's healthy relates to your body's needs and your other dietary choices.

Fruit smoothies contain a lot of natural sugars and carbohydrates that could be unhealthy for you if your body doesn't handle sugar or carbs well or they add to a caloric excess. Pure fruit smoothies (the ingredients you listed contain no fat and barely any protein) are also not particularly satiating (i.e., they're processed quickly in the stomach so you don't feel full very long), so often people who have smoothies for breakfast will do a number on their willpower the rest of the day.

For someone like me who powerlifts four days a week, I need those carbs both to perform and to recover. I add banana to get potassium and sometimes flax if I need those fats. I also add plain 2% yogurt and protein powder to make it a more complete meal and will alternate between blending the ingredients into a smoothie and just preparing them in a bowl to avoid boredom. When I worked out less, I wouldn't drink smoothies because my body would just convert the excess calories to fat.
posted by notorious medium at 5:41 AM on August 31, 2017 [10 favorites]

I have a smoothies most mornings and have maintained weight loss for about 7 years, but my trick is that I measure them and they are roughly the same every day: 3/4 c plain 2% yoghurt, a tablespoon of peanut butter or 6 almonds, half a banana, a spoonful of flax, and 1/2-1/3 a cup of frozen berries, usually a Costco mix. Sometimes I use other fruit if we have fruit on the edge of going bad.

This works for me because there's fat and protein in there and I'm not especially sensitive to sugars, and also because otherwise I tend not to eat breakfast which messses me up. I've sometimes used soy or coconut yogurt but they're more expensive and harder to find unflavoured.

I do work out too, but usually not enough that I have to worry about things like protein powder.
posted by warriorqueen at 5:49 AM on August 31, 2017 [4 favorites]

Smoothies give you more bang for your buck than juices. Unlike juices, if you're blending whole fruits and veggies, you're retaining the fiber since the skin of the fruit/vegetable is often included. I say the rule of thumb for smoothies would be to ask yourself "Would I eat all of this in one sitting?" Don't put 3 cups of berries if you know you couldn't finish that if they were not blended up. Have a protein in your smoothie as well.

Fluid calories do not hold as strong satiety qualities as solid food. Eating a bunch of apples can take 20 or 30 minutes with a lot of chewing and salivation and swallowing. (The whole process, and even before, starts triggering and preparing your body for digestion.) You can drink the same calories in a glass of apple juice in 30 seconds.

So my conclusion, they're fine if you don't go overboard, consider your caloric needs, your activity, and health needs. They're an excellent way to sneak in some veggies and fruits, just be careful on the quantity of things you put in them.
posted by buttonedup at 6:02 AM on August 31, 2017 [2 favorites]

Robert Lustig's lectures about sugar - starting with "Sugar:The bitter truth" might interest you. He concentrates on why the sugar that we take in, in the form of fructose, can be particularly damaging for us - and he explains why in terms of the underlying way that we metabolise it versus sugar in the form of glucose.

Fructose occurs mainly in fruits (and honey) - but normally the fibres that also occur in fruits mean that we feel sated after having just a small number. This is not the case with smoothies were it is possible to take in the fructose from more fruits than we would eat and where the sugar hit is more rapid to us than it would be otherwise.

Like others I would say "it depends" - but you would probably want to have fewer of them or smaller servings than you might otherwise believe was healthy. Or to substitute for just fruit/veggies. And finally to consider the underlying sweetness of whatever it going in there.
posted by rongorongo at 6:47 AM on August 31, 2017 [2 favorites]

When you juice fruit, you get all the sugar without any of the fiber. Sugar is really bad for you and evidence suggests increased sugar consumption is why America has gotten so fat as so full of heart disease. Anyway, there's this great lecture about the health impact of sugar that I recommend and the doctor there explained that sugar typically exists in nature when it is paired with fiber. Fiber fills you up and takes time to digest. But we've stripped all the fiber away from sugar and are just consuming it by itself, which is bad. So, I think smoothies aren't very healthy for that reason.

Also, I am pretty sure that with a smoothie, you're eating the sugar of multiple pieces of fruit whereas if you were just eating fruit whole, you'd have, like, one apple and call it a snack. So you're multiplying the amount of sugar by juicing it.

(Upon reviewing the comments, which I didn't read before writing my own comment, I noticed someone else linked to Dr. Lustig's lecture too. It's quite compelling!)
posted by AppleTurnover at 12:42 PM on August 31, 2017

Fruit smoothies > juicing. But eating a piece of fruit > fruit smoothies.

It's far better to sub leafy greens for the bulk of the smoothie to add additional fiber and cut down the sugar and calories.

If you're not calculating the calories and grams of sugar in your smoothies, try it! You can find this info online, just search for "[fruit] calories" and enter the amount you're using. You might be surprised.
posted by ananci at 1:16 PM on August 31, 2017 [1 favorite]

Mainlining simple carbs -- like one does with a blended fruit smoothy -- is healthy for almost no one who isn't struggling to gain or maintain weight. A milk shake is considerably healthier -- no more calories and a fair share of them fat and protein, too.
posted by MattD at 1:17 PM on August 31, 2017

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