Three cats, one kitchen: the middle one gains 500 g a year, the oldest holds steady, and only the food changed. A 10 g mouthful of dry food stolen at each of two meals is about 76 kcal a day — 30% above what a 4.5 kg cat needs at 250 kcal — which is 0.9 kg of body fat in 90 days. A microchip feeder closes exactly that gap: the lid opens for one implanted chip and stays shut for every other animal.
What the feeder actually reads
The reader sits in the hoop at the front, and a cat must put its head inside it before anything happens. The opening measures about 21 × 15.5 cm, the body 32 × 23 × 20 cm. Three chip formats work: 15-digit ISO 11784/11785 FDX-B at 134.2 kHz (the UK, EU and China standard), 10-digit FDX-A, and 9-digit Avid at 125 kHz, common in the US. One unit stores 32 identities, and the memory survives battery removal.
The bowl holds 400 ml, or two 85 g pouches of wet food; a split bowl serves wet and dry at once. Power is 4 C cells, about 6 months per set, with a red flash every few seconds when they run down. Registering a cat is one button press with its head in the hoop; a SureFlap collar tag, one in the box, covers cats with no chip. The microchip registration guide covers the implant itself.
The arithmetic of one stolen mouthful
Dry food runs about 3.8 kcal per gram, and the theft is small enough that nobody sees it happen. The table is the whole purchasing argument.
| Stolen per meal | Extra kcal per day | Share of a 4.5 kg cat's 250 kcal | Fat gained in 90 days |
|---|---|---|---|
| 5 g | 38 | 15% | 0.44 kg |
| 10 g | 76 | 30% | 0.89 kg |
| 15 g | 114 | 46% | 1.33 kg |
Ten grams is five kibbles and a dirty look. Because the surplus arrives in small daily amounts, it never reads as overfeeding; it surfaces as a body condition score of 7/9 at the annual exam. Obesity prevalence is estimated at 22% to 60%, and food stealing is one mechanism behind the top of that range.
One feeder per cat, not one per house
Since 32 chips register to a single unit, it is tempting to buy one and let all three cats share. That solves the prescription-diet problem — the cat on renal food keeps its own bowl — but it does nothing for portion control, which is why most people buy the device. The working layout is one feeder per cat, at least 1.5 m apart with a sightline break, plus a weekly weigh-in on a 1 g scale. Our multi-cat feeding station guide has the spacing maths, and portion weighing covers the scale side.
What the trials found
The best evidence is a randomised trial at the University of Guelph in 2–3-cat homes, cats at body condition 7–8/9, 12 weeks of calorie restriction. Cats on a technology bundle built around one chip feeder each lost 0.694% of body weight per week against 0.175% for diet alone (P = 0.036). The sample was small — 25 cats enrolled, 9 of 15 and 6 of 10 finishing — so the effect is a direction, not a promise.
A second study of 23 cats compared a plain bowl with an automatic feeder that separates and portions meals: 83.2% of cats on six automatic meals reached body condition 6/9 or better, against 40% on two automatic meals and none of the bowl-fed cats (P = 0.006). Six small meals did not speed weight loss; separation and portioning did. For the calorie maths, see the 12-week weight-loss calorie plan.
Where chip feeders fail
- Sideways eaters. A cat reaching in from the side keeps its chip outside the read zone, so the lid shuts between bites. Push the bowl back and retrain.
- Migrated implants. A chip can shift a few centimetres down the shoulder. If reading gets intermittent, have a vet scanner locate it before blaming the feeder.
- Smear on the reader. Wet food on the hoop window kills the read. Wipe it weekly and wash the bowl by hand; a dishwasher degrades the lid seal.
- Low battery. The failure mode is a shut lid: a cat that cannot eat. The light flashes red every few seconds; keep a spare set.
- Big heads. A 21 × 15.5 cm hoop is tight for a Maine Coon with a full ruff, and every cat must push the lid with its nose at first.
- Timid cats. They eat after the confident cat leaves, which only works with a long lid-close delay; at the shortest setting the lid shuts between bites.
Setting it up in seven days
- Register the chip with the head in the hoop, then check the stored number against the certificate.
- Run training mode for 2–3 days: the lid opens only part way, so the cat sees food without a moving panel.
- Increase the lid opening in steps over the next 4 days, one notch at a time.
- Set the lid-close delay long for a nervous cat, short for a grazer.
- Place units 1.5 m apart and 30 cm off the walls, so no cat is cornered while eating.
- Change wet food daily and hand wash the bowl; never overfill dry food, or the lid will not seat.
- Weigh each cat weekly on a 1 g scale. The feeder controls access, not intake; the scale tells you the plan works.
What it costs
Prices are for the standard feeder; the Connect version adds a portion scale and app logging, costs about US$195 and needs a separate hub. China has no official channel, so that column is a cross-border estimate: UK retail plus shipping and duty.
| Item | US (USD) | UK (GBP) | China (CNY, cross-border) |
|---|---|---|---|
| One standard feeder | 136–199 | 120 | 1,100–1,600 |
| Three feeders (three cats) | 408–597 | 360 | 3,300–4,800 |
| 4 C batteries per feeder | 8–12 | 6–8 | 30–40 |
| Batteries per year, three feeders | 48–72 | 36 | 180–240 |
Against that: a bowl costs nothing, but a cat at 7/9 needs a prescription diet at roughly US$60–90 a month plus bloodwork. The implant is a separate line — the microchip cost breakdown puts implantation and registry at US$45–75.
When a feeder is not the answer
If the thin cat is actively losing rather than failing to gain, a feeder will hide the problem. Losing 5% of body weight in 30 days is a medical sign: hyperthyroidism, diabetes, chronic enteropathy and dental pain all look like this, and no feeding layout fixes them. Get bloodwork first, and see the obesity and safe weight-loss guide for the veterinary side of the plan. Bowl guarding needs its own plan too — food guarding in cats covers the sequence a feeder cannot do.
This article does not replace veterinary diagnosis. Any cat losing weight, or any cat with a body condition score of 7/9 or above, should be assessed by a veterinarian before a diet or a device is chosen.
Frequently asked
Will one microchip feeder work for three cats?
It will open for up to 32 registered chips, so one unit can feed three cats without theft — but all three then eat from a 400 ml bowl with no portion control. If the goal is weight management, you need one feeder per cat, spaced at least 1.5 m apart, and a weekly weigh-in on a 1 g scale to confirm each cat's intake is actually changing.
My cat's chip is a 9-digit Avid. Is that compatible?
Yes. The feeder reads 15-digit ISO FDX-B chips at 134.2 kHz, 10-digit FDX-A and 9-digit Avid chips at 125 kHz, which covers the common US, UK, EU and Chinese implants. If the number will not register, check that the chip has not migrated down the shoulder and try again with the head fully inside the 21 × 15.5 cm hoop; a SureFlap collar tag is the fallback for cats that cannot be read.
Does a microchip feeder actually help a cat lose weight?
It helps by making the plan possible, not by itself. In a randomised trial in multi-cat homes, cats on a technology bundle built around one chip feeder per cat lost 0.694% of body weight per week versus 0.175% with diet alone, though only 15 of 25 cats finished the study. Calories still have to be calculated and weighed; the feeder only guarantees that the cat on the diet is the one eating the food.
Related guides
- Slow Feeder Bowls for Cats: 3 to 10 Minute Meals
- Cat Grass: 7-Day Wheatgrass and 10 cm Grazing
- How to Switch Cat Food: The 7-Day Schedule, With Grams
- Switching an 11-Year-Old Cat's Food: 7-Day Gram Plan
- Taurine in Cat Food: 250-500 mg, and Who Falls Short
- Carbs in Cat Food: Dry Matter, NFE, and the 10% Line