Hollow Victory: We Went Looking for Custard in Britain’s Doughnuts and Found Mostly Air

There is a specific heartbreak known only to the British doughnut eater. You bite in. You meet dough. You meet more dough. You meet a faint suggestion of jam, a rumour of custard, a whisper of something that might once have been filling in a previous life. In 2026, the doughnut has become a masterclass in negative space. We decided to investigate. With science. Or at least with a scale and the sort of confidence usually found three pints deep.

The ‘X-Ray’ Rig That Should Have Been Illegal

We did not have access to a hospital scanner. We had a glass chopping board, a phone torch, a cheese grater and a kitchen scale that occasionally tells us a banana weighs 400g. We called it the Glazed & Confused Doughnut Tomograph. It was, technically, a torch under a chopping board. Legally, it was not an X-ray. Spiritually, it was a Channel 5 documentary.

Backlighting a doughnut reveals shadows where filling should be. A well-filled doughnut glows like a stained-glass window in a cathedral of sugar. A hollow one looks like a Yorkshire pudding that has given up. We photographed 42 doughnuts from supermarkets, high-street chains, petrol stations and one artisan bakery that charged us £4.50 and looked at us as if we had asked for a kidney.

The Jam-Centroid Test

Next, the jam-centroid test. This is exactly as pretentious as it sounds. You cut the doughnut in half, locate the geometric centre, locate the centroid of the filling, and measure the distance between the two. A score over 8mm is ‘filling has fled the scene’. Over 15mm is ‘the jam has emigrated and sends its regards from the next postcode’.

Supermarket jam doughnuts averaged 9.4mm. The premium high-street chain custard doughnut averaged 12.1mm, with one sample so off-centre the custard was practically in a different time zone. The petrol-station ‘mega filled’ doughnut scored 16.8mm and tasted like a sweetened apology.

The Hall of Shame: 2026’s Hollowest Offenders

Ranked by filling percentage by weight, from bad to ‘why is this just bread?’

5. Supermarket eight-pack jam doughnut — 14% filling. The jam is a rumour. The sugar is a threat.

6. Premium high-street chain custard doughnut — 17%, but the custard is whipped to within an inch of its life. It is not custard. It is a dairy-based suggestion.

7. Petrol-station ‘mega filled’ doughnut — 11%. ‘Mega’ refers to the packaging.

8. Artisan seasonal special — 21%, but the filling is a teaspoon of something described as ‘rhubarb and custard foam’. We paid £4.50 for an air pocket with a marketing degree.

9. Vending-machine doughnut — 6%. The filling is not missing. It has been replaced by a philosophical absence. The dough is fine. The idea of filling is what you are buying.

Winner of the wooden spoon: a supermarket ‘custard’ doughnut that contained 4g of filling in a 92g doughnut. That is 4.3%. That is not a filling. That is a smear.

We contacted three high-street chains for comment. None replied. One sent a voucher for 10% off, which felt like being fined for asking.

The Squeeze-and-Weigh Method You Can Try at Home

You do not need a dodgy kitchen X-ray rig. You need a digital scale, a ruler, a small bowl, a spoon and a sense of humour.

1. Weigh the whole doughnut. Write it down. Do not eat it yet.

2. Cut it horizontally through the equator. Try to look scientific.

3. Scrape the filling into the small bowl and weigh it.

4. Divide the filling weight by the total doughnut weight and multiply by 100. That is your filling-to-dough ratio. Anything under 15% is a structural insult. Anything under 10% is a bread roll in a party hat.

5. Squeeze test: press the empty dough half gently between finger and thumb. If it collapses like a bouncy castle with a puncture, you have an air pocket. If it springs back, you have dough. If it squeaks, you have a problem.

Safety note: do not put doughnuts in a microwave to ‘expand the filling’. Do not use an actual X-ray. Do not squeeze a hot doughnut unless you enjoy second-degree jam burns.

What This Means for Your Wallet and Your Soul

We are not saying every doughnut should be a custard-filled water balloon. A good doughnut needs structure. But in 2026, the balance has tipped. We are paying premium prices for dough that has been introduced to filling at a networking event and never followed up.

The fix is simple: buy from places that fill to order, or at least fill with enthusiasm. Use the squeeze-and-weigh method. Ask questions. If a doughnut feels light enough to post with a standard stamp, it is probably mostly air. And if a chain claims its doughnut is ‘generously filled’, ask them to define generosity. Then watch them stare into the middle distance like a custard that has lost its way.

Glazed & Confused will continue to investigate. Next time: the sausage roll-to-pastry ratio. Probably.