How To Thicken Soup (When Using A Soup Maker)

One of the most frequently asked questions I get asked is how to thicken soup.

No matter how you prefer your soup, smooth or chunky, if it turns out too thin and watery for your liking, you’ll likely be disappointed.

Fortunately there are a variety of ways to thicken up a soup, either before, during, or after making the soup. And a few of those methods can also boost the nutritional value of your bowl at the same time, which I’ll cover further down.

Today I’m going to outline the various different methods you can use to get a thicker soup, plus a newer section on thickeners that do double duty for fibre and protein.

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When Should You Thicken A Soup?

When you thicken up a soup will largely depend on what method you’re using to make it. Most of my soup making these days is done in one of my soup makers, but you can use these same methods if you’re making soup in a pan on the hob, in a slow cooker, or even an electric pressure cooker.

How To Thicken Soup Before You Start Cooking

If you think a recipe looks like it’s going to be too thin for your liking, you can add in some ingredients before cooking:

• Chopped potato
• Red lentils (rinsed)
• Tinned butter beans
• Coconut milk

Note: Red lentils and butter beans aren’t just classic thickeners, they’re also genuinely good for fibre and protein. See the dedicated section below for the numbers.

How To Thicken Soup Once It’s Made

Sometimes you won’t know ahead of time whether a recipe is going to turn out thick enough for you. If this is the case, you’ll need to thicken it up during or at the end of cooking. Some ingredients you can add once a soup has been made include:

• Cream (double or single)
• Yoghurt
• Crème fraîche
• Cheese
• Cornflour (mix 1 tsp with a little water or milk and stir into hot soup until thickened to your preference)
• Mashed potato granules
• Thickening granules (found in most supermarkets)

Note: If you’d rather skip the cream or cheese, several of the fibre-boosting thickeners below work just as well stirred in at this stage.

Thicken Soup Without Adding Any Extra Ingredients

If you’d rather stick to the exact ingredients in the recipe, you can achieve a thicker soup by simply increasing the amount of the main ingredients, and/or reducing the stock levels.

You can also achieve a more textured, thicker consistency by blending up part of the soup. If you’re using a soup maker, this will only work on the ‘chunky’ setting, at the end of the cycle, you can manually blend it up in short bursts, checking in between pulses until it’s just how you like it. If you’re making the soup in a pan, slow cooker, or electric pressure cooker, a hand blender gives you full control over the consistency.

Note: Remember, if you’re using a soup maker, you’ll need to stay between the MIN and MAX ingredient lines, depending on the manufacturer’s guidelines.

Thickeners That Also Boost Fibre And Protein

Most of us in the UK fall well short of the recommended 30g of fibre a day, NHS guidance puts the average adult intake at around 20g, and soup is actually one of the easiest places to close that gap, especially if you choose a thickener that works double duty. Here are a few worth trying:

Blended Lentils or Beans (before cooking)

Already mentioned above as a before-cooking option, but worth highlighting on their own.

Green or brown lentils add around 8g of fibre and 9g of protein per 100g cooked, and hold their shape well in chunkier soups.

Note: If you’re using a soup maker, only split red lentils can go in dry, straight from the packet. Whole green or brown lentils need presoaking, or they won’t cook through properly in the time a soup maker allows. If you want their texture and fibre without presoaking, tinned versions are already cooked and can go straight in. They do run a little lower in fibre than dried-and-cooked, and vary by brand, for example, Tesco’s tinned green lentils come in at 5g fibre and 7g protein per 100g, while Napolina’s tinned lentils (brown lentils) offer 7.8g fibre and 6.1g protein per 100g, so it’s worth a quick check of the label.

Red split lentils are slightly lower in fibre (around 6g per 100g cooked, since the hull is removed during processing) but break down completely as they cook, which is exactly why they’re such a good before-cooking thickener, creating a smooth, creamy texture with no dairy needed.

Tinned butter beans add roughly 5g fibre and 6–7g protein per 100g.

All three blend smoothly into a soup with no noticeable change in flavour.

Milled Flax Seed (before or after)

Stir in 1 tablespoon (about 10g) for roughly 3g fibre and 2g protein. It has a very mild, nutty taste that’s barely noticeable in savoury soups, and it thickens the soup slightly as it sits.

Chia Seeds (before or after)

1 tablespoon (about 15g) adds around 5g fibre and 2g protein. Chia swells as it absorbs liquid, so it thickens more noticeably than flax, lovely in a heartier, chunkier soup.

Note: if you want to retain the most omega-3 from flax or chia, stir them in towards the end of cooking, though this doesn’t affect their fibre or protein content either way.

Psyllium Husk (after cooking)

Just ½ to 1 teaspoon (about 2.5–5g) adds a substantial fibre boost with virtually no flavour at all. Sprinkle it in gradually while whisking briskly, or use your soup maker’s blend function for a few seconds, to stop it clumping. Either way, leave it for 5–10 minutes to fully absorb and thicken before deciding if you want more, adding extra too soon is the most common way to end up with an unpleasantly gelatinous soup rather than a nicely thickened one. Because it draws in so much liquid, make sure you’re drinking enough water through the day if you’re using it regularly.

Oat Bran (before or after cooking)

2 tablespoons (about 15g) adds roughly 2g fibre and 2g protein, with a creamy texture and very mild oaty taste. It’s also rich in beta-glucan, a type of soluble fibre linked to healthy cholesterol levels. If you’re adding it to an already-hot soup rather than at the start of a soup maker cycle, whisk it into a splash of cold water or stock first to make a smooth slurry, the same idea as the cornflour method above, then stir that in to avoid clumps. For an extra creamy result, you can also blend it through the soup once it’s cooked.

Greek Yoghurt (after cooking)

Stir through 100g for around 9g protein. Always add it at the end, or it can curdle and split.

Cottage Cheese (after cooking)

Blend through 100g for around 12g protein. It’s naturally curdy, so use the blend function to get a creamy result rather than leaving visible lumps, and like yoghurt, it’s best added at the end to avoid splitting.

Quick Comparison: Soup Thickeners At A Glance

Thickener	When To Add	Nutritional Bonus	Changes The Taste?
Potato	Before cooking	Minimal	No
Lentils (green or brown)	Before cooking	100g cooked: 8g fibre, 9g protein	No
Red split lentils	Before cooking	100g cooked: 6g fibre, 9g protein	No
Butter beans	Before cooking	100g: 5g fibre, 6–7g protein	No
Coconut milk	Before cooking	Minimal (adds fat)	Slightly, adds richness
Cream/crème fraîche	After cooking	Minimal	Slightly, adds richness
Cornflour	After cooking	None	No
Milled flax	Before or after	1 tbsp (10g): 3g fibre, 2g protein	Very mild, nutty
Chia seeds	Before or after	1 tbsp (15g): 5g fibre, 2g protein	Minimal, adds gentle texture
Psyllium husk	After cooking	1 tsp (5g): 3.5g fibre	No
Oat bran	Before or after	2 tbsp (15g): 2g fibre, 2g protein	Mild, oaty
Greek yoghurt	After cooking	100g: ~9g protein, 0g fibre	No
Cottage cheese	After cooking	100g: ~12g protein, 0g fibre	No

Figures above are approximate and will vary by brand and exact product — always check the nutrition label for what you’re using. Tinned versions in particular can differ quite a bit from fresh or dried (see the note on lentils above for an example).

Product Recommendations

As an Amazon Associate I earn from qualifying purchases.

Here’s where I’d recommend picking up the fibre and protein boosting ingredients mentioned above:

Milled Flax Seed two good options worth considering, since they’re both 100% milled flaxseed: Tesco’s Milled Flax Seed Mix and Nature’s Balance Organic Milled Flaxseed.

Chia Seeds I use this one Organic Sevenhills Chia Seeds but they can also be found in supermarkets.

Psyllium Husk NKD Living is a good brand to consider, but there are plenty to choose from

Oat Bran can be picked up in most supermarkets such as Tesco or if you prefer to order it online Bob’s Red Mill is a good choice,

Do you use any of these methods for thickening soup? Or perhaps you have a tip not already mentioned? Let me know in the comments below, I’d love to hear from you!