Feeding Lucy: Why Portioning Cat Food Is Harder Than It Looks

Meet my cat Lucy. Born back in 2008, this sweet girl is rapidly approaching her 17th birthday in June. She spends her days living her best life indoors — usually snoozing on her heated bed or nestled in her favourite blankets.  Spayed, in perfect body condition, and weighing in at 4.07 kg at her most recent vet visit, Lucy is thriving in her golden years.

But like many cat parents, I’ve discovered that feeding Lucy isn’t as simple as just filling her bowl. Figuring out how much to feed her — and how to keep her nutritional needs in check — hasn’t always been straightforward. You’d think pet food companies would make it easy for us cat parents, but reading the feeding guides often leaves me with a massive headache.

Let’s try to feed Lucy together.

According to FEDIAF, the association representing the European Pet Food Industry, the average daily maintenance energy requirement for cats is:

• 75 kilocalories/kg ✕ Body weight (kg)^0.67  for indoor and/or neutered adult cats

• 100 kilocalories/kg ✕ Body weight (kg)^0.67  for lean and active adult cats

Energy is expressed in kilocalories (kcal), which are often referred to simply as 'calories' on food labels and pet care guides.

For Lucy, we’ll use the first equation, which is more suitable for the majority of pet cats. This translates to 192 kcal per day for my girl Lucy. (You can try this online calculator to find your cat's calorie needs!) 

Let’s keep in mind that this is just an estimate. Several additional factors beyond neuter status and activity level can influence daily energy needs including body condition, age, and even breed. While mature cats (ages 7-12) may require fewer calories than a typical adult cat, geriatric cats (>12 years), like Lucy, may actually require more energy due to reduced digestive function. Because of the natural variability in calorie requirements, it’s essential to monitor your cat’s body condition closely and adjust their portions as needed. A body condition score of 5 is considered ideal, though many professionals often consider anything between 4 and 6 as generally healthy.

Now that we’ve got an idea of how many calories Lucy should be getting each day, let’s take a look at the portion recommendations from four pet food brands offering senior-specific formulas. I’ll compare these guidelines to Lucy’s estimated calorie needs and evaluate how practical they are to follow.  

A 2024 study revealed that 60.7% of surveyed cat parents feed their cats a combination of commercial dry and wet food, making this the most common feeding practice. Feeding exclusively dry food comes in second at 16.12%.

With this in mind, let's explore what feeding dry, wet, and a mixture of both might look like in practice for a 4 kg geriatric cat like Lucy.

PURINA ONE

Purina offers general feeding guidelines (based on cat size) and a personalised online portion calculator.

Looking at the table above, Lucy’s daily calories could range from 23% below to 77% above my estimate, depending on which diet and portion guidelines I select. The packaging themselves offer wide portion ranges, leaving me to guess. But even using their personalised portion calculator, I’m still feeding Lucy at least 15% more calories than estimated. 

Not to mention the dry food portions are only provided in grams, which requires me to weigh it (though I admit I’m guilty of just eyeballing it from time to time — dragging out the kitchen scale daily is tedious). But for cat parents without a scale, or if the scale's out of batteries, it leaves them guessing.

LILY’S KITCHEN

Lily’s Kitchen does include a personalised portioning quiz, but no general feeding guides online. 

Lily’s Kitchen consistently recommends Lucy eat about 140 calories per day — roughly 27% fewer calories than my estimate, regardless of the diet type.

The feeding guidelines are all provided in grams, which is common for dry food. However, for wet food, I’m more accustomed to portioning by packaging size (tin or pouch).

• Exclusively Feeding Wet Food: Lucy needs 160g/day, or 1.88 tins if each tin is 85g. Realistically, I’d round up to 2 tins/day, which overfeeds Lucy by 7% from their daily calorie recommendation for her.

• Mixed Feeding: Lucy would need 120g of wet food, or 1.4 tins. Let’s be honest—she’s getting 1.5 tins/day.

While Lily’s Kitchen aims to offer precise feeding guidelines, they overlook the practicality of these recommendations for cat parents. Measuring out fractions of a tin, like 1.88 or 1.4 tins, simply isn’t feasible in day-to-day life. Most of us will round up or down for convenience, which can lead to overfeeding or underfeeding over time.

This lack of alignment between their precise calorie calculations and the realities of feeding from one sized tins feels out of touch with the needs of cat parents. After all, the goal is to make feeding simple and effective, not to add unnecessary guesswork. If feeding guidelines aren’t easy to follow, they lose their value — no matter how accurate they might be on paper (which, frankly, is also in question).

JAMES WELLBELOVED

While they don’t include a personalised portion calculator, they’ve tailored the feeding guides on their label by activity level — a helpful touch. 

Feeding Lucy only dry food leaves her eating fewer calories than estimated — even at the high end of their guide, it’s 14% less. On the flip side, feeding her only wet food exceeds her estimated caloric needs by as much as 43%. And cat parents are still left guessing how much to feed within these ranges. Not to mention, they’ve recommended ¾ of a pouch, leaving me to eyeball portions and store inconsistent leftovers. Is that leftover pouch in my fridge a ¼ portion, or is it actually the remaining ½ from the next pouch I opened? I can’t remember.

ROYAL CANIN

Offers both dry and wet food tailored specifically for ‘Ageing 12+’ cats — separate from their mature line (ages 7–12). This signals a clear focus on the unique needs of geriatric cats like Lucy. 

Royal Canin provides clear portion guidelines rather than vague ranges — although the instructions for mixed feeding are slightly different depending on which label you’re reading. However, I can’t find the calorie content of the food on their site, that must be a mistake right? Wrong. 

Did you know? According to the FEDIAF ‘Code of Good Labelling Practice for Pet Food’ it is not technically required to list the caloric density of the food. 

Legalling, pet food labels must include: 

• Name and Product Description

• Composition (ingredients list)

• Analytical constituent (information about nutrient levels)

• Information about additives

• Best Before Date, Batch Code

• The name of the producer or the distributor and how to contact them for further information

• How to use the product (feeding instructions)

• Weight and/or quantity statement

Unfortunately, many UK pet food brands omit calorie information entirely, or provide it inconsistently. This leaves pet owners to trust that their portion guides are appropriate for their cat’s daily calorie needs — which as we’re already learning is not necessarily the case.

It’s clear that feeding guidelines across brands are inconsistent — leaving me at risk of overfeeding or underfeeding Lucy. Portion recommendations vary widely between diet types and often feature broad, imprecise ranges. And I’m left to weigh odd amounts, open multiple pouches or cans, and eyeball fractions, which introduces even more opportunities for error.

A 2019 study found dog owners consistently mis-measured dry food portions using measuring cups, with the smallest portions (like ¼ cup) being the most inaccurately measured — usually overestimated. Since cats typically eat even smaller portions of dry food, these findings likely extend to cat owners. Proving that accuracy is nearly impossible without a kitchen scale — an extra step that’s both tedious and impractical for daily feeding. And it’s not just about dry food. Wet food guidelines often suggest fractions of pouches or tins — which invites similar inaccuracies.

The challenge further grows when owners mix products from different brands. And without calorie transparency on all brands, cat parents are left guessing at accurate portions — and guessing wrong can have serious consequences for their cat’s nutrition and health. 

KatKin uses a proprietary algorithm to calculate your cat’s daily energy needs that accounts for current body condition and activity level.

For Lucy, she’s recommended a 161g daily portion. At 201 calories per day, Lucy would be receiving just 5% more than my initial estimate, which could be ideal for her geriatric age since slightly increased calories may be appropriate. 

Even better? I don’t need to measure, guess, or calculate anything myself. KatKin delivers personalised daily portions, pre-split into convenient morning and evening meals. All I have to do is open and serve — simple as that. And if I ever feel Lucy isn’t getting the right portion, I can always adjust her information in her profile which will automatically update her portion size. But since she currently has an ideal body condition score, I’m pretty confident her portion size is just right. 

KatKin’s fresh meals are also formulated for all life stages, so they’re perfectly suitable for senior cats like Lucy. I don’t need to worry about selecting the right lifestage formula.

At KatKin, we believe calorie transparency should be a standard on all pet food labels. While we don’t expect cat owners to do the math themselves (that’s our job!), we do think they should have access to this information to feel confident about their cat’s nutrition.

Pet owners not only need feeding guidelines that are easy to understand, but also ones that are easy to follow. KatKin delivers on both fronts — making it effortless to ensure your cat is happy, healthy, and properly nourished.

95% of cat parents see health improvements when they switch to KatKin's fresh, perfectly portioned recipes. Want to see for yourself? Sign up for a 14-day trial box here.