How many chestnuts a day: calories, portion and why they don't count as nuts

Every October the sacks of chestnuts come back to the market stalls, and with them the same question: if it's a nut, does it pile on the calories like a handful of walnuts? The short answer is no, and the reason has nothing to do with calories: it's that a chestnut contains almost no fat. A hundred grams of shelled dried walnuts carry 68.1 g of fat; a hundred grams of fresh chestnut carry 1.7 g. They are two different foods sitting on the same shelf.

That also means the chestnut doesn't do the job a walnut does. If you buy it expecting the fat profile of a nut, you bought the wrong product. Here are the figures from the official food composition tables, what can legally be claimed about it, what portion makes sense, and how it fits into an ordinary day without strange arithmetic.

In short

• Fresh chestnut has 174 kcal and 1.7 g of fat per 100 g, according to the Italian CREA tables. Shelled dried walnuts: 702 kcal and 68.1 g of fat.
• What it does carry is starch: 25.3 g per 100 g. Nutritionally it is closer to a potato or a slice of bread than to the nuts it shares an aisle with.
• A sensible portion is 100-150 g of peeled chestnut, which roasted is roughly 10 to 15 medium pieces. It takes the place of the starchy side dish, not the place of a handful of nuts.
• At 100 g it clears the "source of potassium" threshold (395 mg, and 15% of the reference value is 300 mg). It is the only health claim that can legally be attached to it in the EU.
• Roasting costs vitamin C: up to 77% in the study that measured before and after. Don't buy chestnuts for vitamin C.
• Raw chestnuts are not food. More than half of their starch behaves as resistant starch until heat gelatinises it.
• Chestnut flour is not a "light" flour: 318 kcal and 62 g of carbohydrate per 100 g, almost the same as wheat flour. Its real advantage is different: no gluten.

What's inside a chestnut, and why it changes everything

Botanically the chestnut is a genuine nut: an achene with a shell. The trouble is that in everyday speech "nut" means something else — walnut, almond, hazelnut, cashew — and those are oilseeds with 50 to 70% of their weight in fat. The chestnut left that group by evolution: it stores its energy as starch, like a tuber, not as oil.

The figures from the Centro di ricerca Alimenti e Nutrizione (CREA), Italy's official food composition database, last updated in December 2019, give per 100 g of edible portion of fresh chestnut: 174 kcal, 55.8 g water, 2.9 g protein, 1.7 g fat, 36.7 g available carbohydrate — of which 25.3 g starch and 8.9 g sugars — 4.7 g fibre and 395 mg potassium. The French Ciqual table (ANSES, 2020 edition) gives 144 kcal, 1.4 g fat, 28.8 g carbohydrate, 4 g fibre and 359 mg potassium.

Both tables are official and they disagree, and it is worth saying why: the difference is almost entirely water. CREA describes a chestnut with 55.8 g of water per 100 g, Ciqual one with 62.7 g. A drier chestnut concentrates more of everything. That is why any chestnut figure that doesn't say whether it refers to the fresh, roasted, dried or milled product means very little. The real range for fresh chestnut is 144 to 174 kcal per 100 g.

Roasting does the predictable thing: water leaves and everything else rises. CREA gives roasted chestnut 210 kcal, 2.4 g fat, 41.8 g carbohydrate, 8.3 g fibre and 515 mg potassium per 100 g. Keep that in mind when you compare prices and portions in the dried fruit and nuts aisle: 100 g of fresh chestnut in the shell is not 100 g of roasted, peeled chestnut. The edible portion of a fresh chestnut is 85% of its weight, and of a roasted one 82%.

How many chestnuts a day: six concrete decisions

1. Count the portion in grams, not in pieces

A medium peeled chestnut weighs between 8 and 12 g, so "ten chestnuts" is anything from 80 to 120 g. A usable rule: 100-150 g of peeled chestnut is the portion that works as a side dish or a substantial snack, which is 174-260 kcal boiled from fresh, or 210-315 kcal roasted. Buy by weight: the 500 g pack of extra fresh chestnut from Viladrau gives two or three portions once you subtract the shell and the hollow ones. In nuts and bulk you can take exactly the amount you plan to roast this week instead of a whole bag.

2. Swap them for bread or potato, not for walnuts

This is the most common mistake. If you add 100 g of roasted chestnuts to a plate that already has its share of carbohydrate, you have just added 41.8 g of available carbohydrate. If instead they replace the side dish, the swap comes out almost flat: 100 g of roasted chestnut has 41.8 g of carbohydrate and 100 g of bread is in the same neighbourhood; 100 g of potato boiled in its skin, by contrast, stops at 17.9 g. Chestnuts are a dense side: they work best in the place of the rice or the mash, with a portion of protein and some vegetables alongside.

3. Roast them or boil them; raw doesn't count

The starch in a raw chestnut is largely inaccessible: a paper published in Animal Feed Science and Technology in 2013, which used it as a source of resistant starch in weaned piglet diets, measured that 57.6% of the starch in raw chestnut behaves as resistant starch. It is an animal study and it doesn't transfer directly to people, but it explains what anyone who bites into a raw chestnut notices: it is hard, astringent and badly tolerated. Heat gelatinises that starch and makes it digestible. If you don't want to turn the oven on, the precooked chestnuts from Naiciña are already cooked and peeled and warm through in two minutes; and the frozen aisle has seasonal options so you have the ingredient outside October and November.

4. Chestnut flour is for blending, not for replacing

Chestnut flour has, according to CREA, 318 kcal, 3.7 g fat, 62 g carbohydrate, 13.8 g fibre and 847 mg potassium per 100 g. In other words: it is not a light flour, it is an ordinary flour with a lot of fibre and a strongly sweet flavour. What it doesn't have is gluten, which makes it genuinely useful for anyone avoiding it — Regulation (EU) 828/2014 sets the "gluten-free" threshold at 20 mg/kg in the food as sold, so if this matters to you, read the label rather than reasoning from the ingredient. In baking it works replacing 20 to 30% of the total flour: above that the cake turns dense. We stock the 500 g Naiciña chestnut flour and the gluten-free chestnut flour from Salud Viva, alongside the rest of the flours.

5. If you're after vitamin C, roasted chestnut is not the route

Raw chestnut does contain vitamin C, and a fair amount for a food eaten cooked: the work by Barros and colleagues published in Food Chemistry in 2011 (volume 128, pages 165-172) measured between 400 and 693 mg per kilo of dry weight depending on cultivar, from "Lada" to "Martaínha". The problem is what happens next: the same authors measured losses of 25-54% on boiling and 2-77% on roasting. That very wide range for roasting is the honest figure: it depends on time and temperature, and in practice you cannot know where in the range you landed. For vitamin C, fresh fruit is a far more reliable bet, and if what worries you is autumn immunity, that is covered in our article on zinc or vitamin C.

6. Potassium is the only thing that can legally be claimed

Here there is an authorised claim the chestnut does meet. The nutrient reference value for potassium, under Annex XIII of Regulation (EU) 1169/2011, is 2,000 mg a day, and to say "source of" you need 15% of it, that is 300 mg per 100 g. Fresh chestnut gets there with 395 mg and roasted with 515 mg. On that basis, Regulation (EU) 432/2012 permits exactly these three sentences, in this wording:

"Potassium contributes to normal functioning of the nervous system."

"Potassium contributes to normal muscle function."

"Potassium contributes to the maintenance of normal blood pressure."

To put those 395 mg in context: in 2016 EFSA set an adequate intake for potassium of 3,500 mg a day for adults and 4,000 mg for lactating women. A 150 g portion of roasted chestnut supplies around 770 mg, about 22% of that reference. It isn't magic; it's a side dish that happens to bring potassium with it. If potassium and magnesium make you think of cramps, the one whose evidence we have reviewed is the vitamins and minerals range, and we take it apart in the magnesium article.

Chestnut, walnut and potato: the comparison that matters

This is the table that settles the question in the headline. All figures are from CREA, per 100 g of edible portion. It also shows why the article on how many walnuts a day and this one reach different conclusions: they are not the same food.

Two quick readings. First: the chestnut sits four times below the walnut in calories and forty times below in fat. Second, less comfortable: on carbohydrate it plays in the bread league, not the walnut one. Both are true at once, which is why "is it fattening?" is the wrong question; the useful question is "instead of what am I eating it?".

Chestnuts at home: which format for what

Each format solves a different problem, and the fresh season is short. This table is the working guide to an October and November pantry.

La Castanyada: what people actually buy for 31 October

In Catalonia the chestnut is not just a season, it's a date. La Castanyada, on the night of 31 October and All Saints' Day, is built on three things: roasted chestnuts, sweet potato and panellets — the small marzipan-style sweets typical of the region. And panellets are where it pays to read the label, because the expensive ingredient is the pine nut and there are versions where it is scarce.

In nougat, polvorones and panellets you'll find the seasonal ones, including the pine nut panellets. If you make them at home, pine nuts come in bulk — the way not to pay for a 45 g package — or in closed formats: 150 g Galderic pine nuts and 45 g Artemis pine nuts. And oven-roasted organic sweet potato is the other half of the tray.

The shopping list

For an October week with chestnuts in it, without overcomplicating things:

• The base: fresh chestnut and bulk in nuts and dried fruit, and flours if you're going to bake.
• The 31 October table: seasonal panellets and nougat and vegetables for the sweet potato and the squash.
• To snack on: Sol Natural sweet potato chips and biscuits chosen with some judgement.
• To complete the plate: pulses in bulk and seeds, which is where the protein and the fat the chestnut lacks actually are.
• To go with it: coffee and teas, which with roasted chestnuts is the whole afternoon snack.
• If you'd rather we brought it to you: the seasonal organic baskets, and a look at the offers.
• And if you came from the supplements aisle: superfoods, diet and nutrition and digestive system, with the warning in the next section.

Do you need a chestnut supplement?

No. And it's worth saying plainly, because this is a product we sell: the chestnut has no authorised health claim of its own in the European Union. The only thing that can be asserted is the potassium one, and it can be asserted because there are 395 mg in 100 g, not because the chestnut has anything special about it. Anything you read about chestnuts and "sustained energy", detox or weight loss has no regulatory backing.

The opposite case has to be said too. The authorised claim for walnuts does exist — "Walnuts contribute to the improvement of the elasticity of blood vessels" — and its condition of use is a daily intake of 30 g of walnuts. That claim belongs to the walnut, not to the chestnut, and it does not transfer. If what you want is the effect of a fatty nut, buy walnuts rather than chestnuts: it's in the article on how many walnuts a day. If what you want is omega 3, even less so: the chestnut has 1.7 g of total fat, and that is covered in the omega 3 article.

Where the chestnut does contribute something hard to argue with is fibre. At 4.7 g per 100 g fresh it meets the "source of fibre" threshold in Regulation (EC) 1924/2006, which is 3 g per 100 g; and roasted, at 8.3 g, it clears the "high fibre" threshold of 6 g. Given that EFSA puts the fibre reference at 25 g a day and almost nobody gets there, that is a real advantage rather than a sales line: it's laid out in how much fibre per day. And for protein, which the chestnut barely has at 2.9 g per 100 g, the place is how much protein per day. If on top of that you're coming out of summer with your digestion unsettled, well-cooked chestnut starch and fermented foods get along well.

Where to buy chestnuts in Barcelona and Sant Cugat

Fresh chestnut is a perishable product with a short season, and that changes where it's worth buying. We have three shops, all in the Barcelona area:

• Provença 242, 08008 Barcelona — Eixample district, between Balmes and Enric Granados.
• Còrsega 78, 08029 Barcelona — Eixample, close to Sants station.
• Antoni Bell 2, 08174 Sant Cugat del Vallès — Volpelleres neighbourhood.

You can call +34 683 118 961 to ask whether chestnuts came in that day, because fresh deliveries are not the same every week, or write to linverd@linverd.com.

And here is what a marketplace cannot give you: a hollow chestnut weighs less and sounds different, and that can only be checked by hand. Buying in bulk, you take the 500 g you're going to roast on Thursday, discard the ones with a worm hole and carry home only the ones that feel heavy for their size. Nobody lets you do that with a sealed box that has spent three days in a lorry. Our extra fresh chestnut comes from Viladrau, in the Montseny massif, a little over an hour from the shops: that's why it arrives firm rather than soft.

Frequently asked questions

How many chestnuts can you eat in a day?

As a side dish or a snack, 100-150 g of peeled chestnut is a sensible portion: roughly 10 to 15 medium roasted pieces, or 210-315 kcal. There is no safety limit to respect; there is a question of fit: those 40 g of carbohydrate take the place of the bread or the rice in that meal, they don't get added to it.

Are chestnuts fattening?

No more and no less than any starchy food. A hundred grams of roasted chestnut has 210 kcal, against 702 kcal for shelled walnuts. The real risk isn't the chestnut, it's eating it on top of the carbohydrate the plate already contained, and eating it roasted while standing up, uncounted, in amounts you wouldn't eat at the table.

Where can I buy organic chestnuts in Barcelona?

In our shops at Provença 242 and Còrsega 78, in the Eixample, and at Antoni Bell 2 in Volpelleres (Sant Cugat del Vallès), as well as the online shop. The extra fresh chestnut comes from Viladrau, in the Montseny, and the season runs from October to November. Phone: +34 683 118 961.

Can you eat raw chestnuts?

It isn't a good idea. Raw chestnut starch largely resists digestion until heat gelatinises it, and it is astringent because of its tannins. Roast them in the oven at 200 °C for 20-25 minutes, with a cross cut in the shell so they don't burst, or boil them for 25-30 minutes.

Is chestnut flour suitable for coeliacs?

Chestnuts contain no gluten, so neither does the flour, but what matters is the packing and the risk of cross-contamination. Regulation (EU) 828/2014 allows the "gluten-free" statement only below 20 mg/kg in the product as sold: look for that statement on the label rather than assuming the raw material settles it. The Salud Viva flour carries it.

Which has more potassium, a chestnut or a banana?

Roasted chestnut, at 515 mg per 100 g, sits above what is usual in fresh fruit. With 100 g of fresh chestnut you already pass the "source of potassium" threshold of 15% of the reference value, which is 300 mg. If you have kidney disease and have been asked to watch your potassium, that is not good news: discuss it with your medical team.

What's the difference between a chestnut and marron glacé?

Marron glacé is the same chestnut candied in sugar syrup, so its profile no longer resembles the fruit's: it's a confection. For the table on 31 October it makes more sense to combine roasted chestnut with sweet potato and panellets, and leave the candied version to be what it is, a dessert.

In summary, and what to do this week

The chestnut is a seasonal side dish that is low in fat, generous in fibre and carries enough potassium for the law to acknowledge it. It isn't a fatty nut and it doesn't replace walnuts. Buy 500 g in bulk, roast them the same day and put them where the rice would go. You have the nuts and bulk section in the online shop, the three physical shops to pick them out by hand, and the rest of the articles on the health blog.

If you got this far for the label-and-claims part, the supplement manual applies the same criteria to vitamins; if what interested you was autumn and rest, see chronic stress and the nervous system and melatonin for sleep. And if you haven't been to the new shop yet, we describe it here.

This information is for general guidance and does not replace advice from a health professional. If you have kidney disease, diabetes or any other condition that requires monitoring potassium or carbohydrate, consult your doctor or registered dietitian before changing your diet.