I got on trying to eating more healthy and as a part of that, I take a few tomatoes, cucumber and garlic and blend that into a sort of a drink. It's far more convenient and quick to smash a bunch of veggies into a blender and mix the crap out of them, rather than slicing and hacking. It also scales better - making a mixaroo of 3 or of 5 tomatoes takes the same amount of time, whereas slicing time is proportional. So I'm aiming at eliminating any obstacles along the way to wiser food choices.

I'd like to make it less liquidish, aiming for a thicker texture. I've tried adding broccoli, cauliflower, nuts and seeds. I tried adding oat flower and soy protein powder. It gave an improvement but to be acceptably substantial, I need to push in quite a lot, which kind of defeats its purpose.

Is there something very calorie thin but structurally dense that I could smash into my drink? Extra bonus if it's rich on fiber.

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    is there a reason you can't just slice them into a salad, which is composed of solids, and just eat that? Why are you trying to make a thick drink? Without knowing that, suggestions are hard to come up with. Commented Aug 1, 2020 at 0:50
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    @KateGregory because that’s a different food? The answer to “how do I improve my smoothie” is not “make a salad instead."
    – Sneftel
    Commented Aug 1, 2020 at 8:06
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    But knowing what you want in a smoothie is key to improving it Commented Aug 1, 2020 at 10:32
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    @KateGregory I agree with the comment by Sneftel (although I'd word it much more humbly and cautiously). As to your question, the choice of medium (or whatever we may call it) is that it's far more convenient and quick to smash a bunch of veggies into a blender and mix the crap out of them, rather than slicing and hacking. It also scales better - making a mixaroo of 3 or of 5 tomatoes takes the same amount of time, wheras slicing time is proportional. So I'm aiming at eliminating any obstacles along the way to wiser food choices. So, have you a suggestion on thickening? Commented Aug 1, 2020 at 20:14
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    This happens a lot, that I ask "why x" and people hear "you shouldn't x". Thanks for answering despite thinking I was saying "make a salad", which I wasn't. The answers below are pretty good, really. Another possibility might be crushed ice. Commented Aug 1, 2020 at 21:51

6 Answers 6


Your primary option if you want to add a thickener, you can use any hydrocolloid you wish. I will not list them here again, since it isn't necessary that every single question on thickeners on the site gets the full list. You can download Martin Lersch's free reference book, Texture: a hydrocolloid recipe book, and start experimenting. I can also not tell you which one will be the best for your case - they all produce different textures, and it depends on your personal preference which one to use, and anyway, you have to see which one is accessible for you.

A second option for getting any tomato based liquid thicker is to either cook it down on your own, or to replace some of the fresh tomatoes by concentrated tomato paste.

The third option, deseeding, was already given in Keith Ford's answer.

And you already mentioned the fourth, bulking up with dry ingredients such as your soy powder.

I would say the four together give you a pretty wide range of alternatives, try them out and see which one you can best live with.

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    @KonradViltersten be careful with xanthan...goes from thickening to snotty in texture very quickly. Start with .5%. You probably won't go over 1%. Wait a bit after mixing in, before you decide to add more.
    – moscafj
    Commented Aug 1, 2020 at 22:29
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    @KonradViltersten I suggest that you simply get Lersch's book and see how he suggests using xanthan and guar, instead of trying to glean the knowledge about using it piece by piece - you don't have to go to a library or pay money, just download it, it's CC. Information on bioavailability is off topic on the site, moscafj cannot answer even if they have something to say about it :(
    – rumtscho
    Commented Aug 2, 2020 at 9:14
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    @KonradViltersten That's the beauty of the Wayback Machine! I had already edited rumtscho's post to include it. web.archive.org/web/20200420203644/https://blog.khymos.org/… Commented Aug 2, 2020 at 20:20
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    @ElizaWilson I'm getting a 503 error at that link. I'd like to humbly suggest that at least some basic information about hydrocolloids be added to the answer, even if it seems redundant with other answers on Cooking.SE. We can't know the future of those other answers or linked content - providing some of the information here give this answer greater resilience, clarity, and completeness. Commented Aug 3, 2020 at 5:34
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    @ToddWilcox the book lists 16 different hydrocolloids, each of which can be used for the puprose of the OP, and the only thing they have in common is that they 1) thicken, 2) are edible, and 3) most of them have no calories. Everything else - in what pH range they work, what is the texture quality of the gel they produce, do they have special requirements about temperature, sugar content, etc. - is different. If we were to reproduce this here, it would mean reproducing the book itself minus the recipes.Besides their having been mentioned elsewhere on cooking, adding 16 paragraphs is too long.
    – rumtscho
    Commented Aug 3, 2020 at 7:47

Your "drink" sounds a lot like gazpacho. When making gazpacho, bread is often blended in, primarily to increase the viscosity...not necessarily "calorie thin", but an option. Olive oil is also emulsified into the mix, creating an enjoyable texture, and adding to the flavor.

  • Ah, I realize now that I'm not the first person to discover a nice dish. Apparently, like you just mentioned, there's already something like that. Well, yeah, we're trying to make something gazpachish, here. I've tried extra virgin olive oil and it made a notable difference. I'm also sure that some bread or maybe oat flour will do that to. However, we have the calorimetric as an important parameter. I need to find something oily, floury that's "pure plastic", so to speak. Suggestions? Commented Aug 1, 2020 at 20:20
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    @KonradViltersten see rumtscho's response. Go hyrdrocolloid. Unfortunately, the Lersch website (Khymos) appears disabled at the moment. But there is plenty of info on hydrocolloids on this site and on the nets.
    – moscafj
    Commented Aug 1, 2020 at 21:34
  • I've found two products in my local store, which I'll visit tomorrow. One is guar gum with zero absorption (basically tummy plastic). The other is xanthan gum. Any thought on any of them? Commented Aug 1, 2020 at 22:17

The reason that your "drink" is thin, is that you are not removing the water and seeds from the Tomato. Peel them and take away the water and seeds before you put them in the blender. Go here https://www.deliaonline.com/cookery-school/techniques/how-to-skin-and-de-seed-tomatoes

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    Based on another comment, I realized why it's important to thicken the existing state instead of not getting into it. I didn't realize it explicitly before but the main reason is convenience. And peeling/drying tomatoes doesn't scale very well if I would go with 5 instead of 3. Mixing the stuff, on the other hand, take the same amount of effort. Commented Aug 1, 2020 at 20:16
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    @KonradViltersten I don't understand the suggestion to peel the tomatoes. But you can easily get rid of much of the liquid with little time and effort just by cutting the tomatoes in half and scooping out the insides by hand.
    – Daron
    Commented Aug 2, 2020 at 1:56
  • @Daron : depending on the variety of tomato, you can sometimes just cut in half, give them a squeeze and a bit of a flick, and remove a good amount of the seeds & gel.
    – Joe
    Commented Aug 4, 2020 at 20:24

I suggest adding flax meal. This is very high in fiber, but not very high in digestible carbohydrates. It won't take too much, so the surge in calories won't be so bad. You will have to measure it out. Unfortunately, the Omega oils in this have some calories.

The option that better fits your criteria is psyllium husk powder; plenty of thickening and fiber, yet almost no calories. 30 grams will be 100% of your daily fiber, but just 100 calories. That would make your drink plenty thick, with not to much taste.

I prefer the way flax tastes though, and it is super healthy with Omegas and protein and such.

There are some more things to add on this list; perhaps Chia? I haven't tried them all, so can't comment on them. It might be worthwhile to research each individually.

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    I've never played with psyllium husk, but ground flax makes a decent gel when you mix it with water. (it's a common replacement for eggs in vegan baking)
    – Joe
    Commented Aug 4, 2020 at 21:58

One alternative, instead of adding thickeners, would be to remove some water. As mentioned in Keith Ford's answer, you could remove some water manually by de-seeding the tomatoes.

OTOH, there are various ways to systematically reduce the moisture of the smoothie itself:

  • The old-school approach would be to reduce it in a pot on the stove. That is, keep it just barely simmering, uncovered, for a long time, to evaporate off a bunch of the excess water. This does, of course, imply that the result will be cooked, which may not meet your criteria. (Side note: if you are okay with cooking it, you can get a lot of thickening out of a small amount of starch by mixing it in cold and then cooking the whole thing for a few minutes.)
  • A classic, no-cook, but still time-consuming option would be to pour the stuff into a food dehydrator, using the liner sheets that are used for making fruit leather from fruit purée. The heat in a dehydrator is low enough that you're not cooking anything, just speeding up evaporation. If your objective is a thicker drink, as opposed to a 'leather', just take it out after a fraction of the time given in fruit leather recipe instructions.
  • The quick, easy way to make a thicker smoothie without using a thickener is to use a juicer instead of a blender. Juicers separate the liquid and the pulp as they go, so you can easily just take the heap of pulp, mix however much of the liquid back into it as it takes to get the consistency you want, stir well, and dispose of the leftover liquid any way you like (down the drain, use as cooking liquid, etc.).
  • Another option would be to put it into a cloth bag or similar, and let some of the liquid drip away. (look up recipes for "tomato water", and save the other part). Also, cooking might cause additional thickening besides just evaporation as tomatoes contain pectin
    – Joe
    Commented Aug 4, 2020 at 20:29

A super-easy solution with an ingredient many people have in their house:

Mashed potatoes.

I've successfully used a bit of mashed potato to thicken salad dressing, it might suit your needs here. (You can even buy dried mashed potato powder, which thickens stews nicely but has usually had most of the nutrition processed out of it.)

I also sometimes sweeten soups with sweet potatoes, but they have a more noticeable flavor that doesn't fit your list.

  • That's a good suggestion on the thickening part. However, thta can be achieved by e.g. oat flower too. My consideration are the calorimetric - I want to get as little calories per volume unit as possible and flour/potatos hit over 300 kcal per 100g, which is rather much. Commented Aug 2, 2020 at 23:16

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