Daily BiscuitsResting energy requirement
A cat’s resting energy requirement (RER) in kcal/day is 70 × (body weight in kg)^0.75. Daily maintenance needs for an adult are RER multiplied by a life-stage factor: roughly 1.2 to 1.4 for neutered adults, 1.4 to 1.6 for intact adults, 1.0 for inactive or obesity-prone cats, and 0.8 × RER of ideal weight for weight loss. Kittens are different: their needs follow how far they are toward their adult weight (the NRC 2006 growth equation), about 200 kcal per kg at 10 weeks easing to about 80 per kg by 10 months. That is roughly 2.5 to 3 × RER when very small, falling toward 1.5 × as they near adult size. These are starting points; for adults, recheck body condition every two weeks or so, and weigh kittens every week until they are one.
Feeding kittens
Kittens need a food labelled for growth or all life stages, fed four small meals a day under four months, three until six months, then two or three. How much depends on how far along they are toward their adult weight, not just their age (the NRC 2006 growth equation): about 200 kcal per kg at 10 weeks, easing to about 80 per kg by 10 months. Very small kittens need about 2.5 to 3 × RER, and that falls toward 1.5 × as they near adult size. Weigh a kitten every week until they are one so the portion keeps up. Do not restrict a growing kitten’s food for weight reasons without veterinary advice; instead choose a complete kitten diet and measure portions. Move to adult food at around 12 months. Big breeds such as the Maine Coon, Siberian, Ragdoll, Norwegian Forest Cat, British Shorthair and Savannah keep growing for longer, so they stay on growth feeding to about 15 months.
The 10% treat rule
Treats and table food should make up no more than 10% of a cat’s daily calories. Above that, the main diet is diluted and no longer complete and balanced. Count treats, lickable pastes and dental chews in the daily calorie budget.
How owners actually feed, and why weight plans fail
In APOP's 2025 survey, 43% of cat owners described their cat as above ideal weight (33% a year earlier); 48% knew what body condition scoring is and fewer than one in four had been given a score by their vet. Feeding method: 3% weigh food, 37% use a cup, 29% free-feed, 19% guess, 12% use an automatic feeder. Of the 53% who had tried a weight-loss plan, 19% reached target and 48% lost some weight; 35% used a therapeutic diet. Nearly half would consider a weight-loss drug. A 2025 AJVR analysis explains one reason plans stall: cutting an ordinary adult or over-the-counter light food to weight-loss calories pushes protein, amino acid and vitamin intakes below NRC recommendations, which purpose-formulated veterinary weight-loss diets avoid. Practical order: weigh the food in grams, stop free-feeding, target 0.5 to 2% loss a week, and for a large cut ask the vet about a formulated weight-loss diet.
Read a food label in 60 seconds
The ingredient list is the weakest signal on the bag. Three lines on the back panel tell you almost everything.
- Find the AAFCO statement. “Complete and balanced for adult maintenance” (or growth, or all life stages) is the pass. “Intermittent or supplemental” is a topper.
- Check the life stage matches your cat.
- Find the calorie statement: kcal per can or per cup. That’s what turns the feeding target into a portion.
- Look up the maker: do they employ a nutritionist and run feeding trials? Purina, Hill’s, Royal Canin and Iams say yes in public.
- Premium and holistic have no official meaning, and natural and human grade are about sourcing and handling, not nutrition. Grain-free says nothing about quality.
Source: AAFCO Reading Labels; WSAVA Selecting a pet food; Tufts Petfoodology
Switching food over a week
Change a cat’s food gradually, over about seven to ten days, because a sudden switch can cause vomiting, diarrhoea or a cat refusing the new food. A common plan: days 1 to 2, 75% old food and 25% new; days 3 to 4, half and half; days 5 to 6, 25% old and 75% new; from day 7, all new food. Some cats need longer, so if there is a little digestive upset, stay on the same mix for a few more days before moving on. Keep the daily amount at the cat’s calorie target, using each food’s own label, since foods differ in calories per cup or can. Call the vet if the cat keeps vomiting or has diarrhoea, has not eaten in 24 hours, or seems unusually lethargic.
Source: PetMD, “How To Switch Cat Food” (Brittany Kleszynski, DVM)
When to call the vet
Call the vet if the cat keeps vomiting or has diarrhoea, has not eaten in 24 hours, or seems unusually lethargic.
Source: PetMD, “How To Switch Cat Food” (Brittany Kleszynski, DVM)