A scale gives you one number; body condition tells you what that number is made of. A 5.2 kg cat at body condition score 7 is carrying roughly 20% more fat than it needs, while a 4.1 kg cat at score 4 with visible spine is underfed in the way that shortens life. Both are settled with the same three moves: stand the cat on a flat surface, run your hands along the ribs, then look down at the waist.
Hands first, then eyes
Put the cat standing on a table, stand behind it, and lay both thumbs along the spine with your fingers wrapped around the rib cage. The standard comparison is the back of your hand: knuckles means too thin, the flat of the hand means ideal, the palm means too heavy. Then look from above for an hourglass behind the rib cage, and from the side for a belly line that rises from the sternum toward the hind legs. A cat with a pendulous belly that swings when it walks scores at least 7 even if the ribs still feel findable.
What each of the nine scores looks like
The nine-point scale is the common clinic standard, with 5 as ideal and 4–5 as the healthy band. Roughly 10–15% of body weight separates each point above 5, which makes score 7 about 20–30% over ideal and score 9 over 40%.
| Score | Ribs | Waist from above | Belly from the side |
|---|---|---|---|
| 1 | Visible from across the room, no fat | Severe hourglass, spine and hips sharp | Deep tuck, abdomen hollow |
| 2 | Easily seen, minimal fat cover | Marked hourglass | Clear tuck |
| 3 | Easily felt, thin fat layer | Obvious hourglass | Moderate tuck |
| 4 | Felt with light pressure | Visible hourglass | Slight tuck |
| 5 | Felt with light pressure under thin fat | Clear hourglass behind the ribs | Gentle rise toward the hind legs |
| 6 | Felt with slight pressure | Waist present but softened | Level belly line |
| 7 | Felt with moderate pressure | Waist barely visible | Fat pad starting at the flank |
| 8 | Felt only with firm pressure | No waist, back looks broad | Belly sags below the elbow line |
| 9 | Not palpable under thick fat | Round or pear-shaped | Distended abdomen, fat pads on the chest |
Muscle score is a separate four-step grade
Muscle condition is scored on its own axis, from normal to severe loss, by feeling where muscle should sit over bone. Check four places: the temporal bones on the sides of the skull, the shoulder blades, the lumbar vertebrae, and the pelvic bones. Normal means the bones are covered and only a rounded ridge is felt along the spine. Mild loss means the spine and shoulder blades feel sharper but are still padded. Moderate loss means the bones are obvious to the eye, the temples look sunken, and a gap is felt between skin and bone. Severe loss means no muscle at all between skin and bone, a hollow along the spine, and a triangular head. Grade it every month in any cat over 10, because it moves faster than weight does.
The senior cat whose weight looks fine
A 12-year-old at score 5 with moderate muscle loss has probably traded 10% of lean mass for fat, and the scale shows nothing wrong. The usual causes line up in a short list: chronic kidney disease, untreated hyperthyroidism, inflammatory bowel disease or intestinal lymphoma, diabetes, dental pain, and ordinary age-related sarcopenia. A cat that eats well and still loses muscle needs bloodwork (CBC, chemistry, T4, urinalysis), a UPC and blood pressure, and often an abdominal ultrasound plus cobalamin. Weight that holds steady while the spine gets sharp is a reason to book a visit, not a reason to relax.
Turning the score into grams per day
Start with resting energy requirement: 70 × body weight in kg to the power 0.75. Multiply by 1.2 for a neutered indoor adult, 1.3–1.4 for an intact or very active cat, and 1.0 for a cat on a weight-loss plan. For an overweight cat, calculate from the target weight, not the current one, then feed 80% of that resting figure. Safe loss is 0.5–1.5% of body weight per week; faster than that in a cat risks hepatic lipidosis. Dry food runs about 3.5–4.2 kcal per gram and typical wet food 0.7–0.9 kcal per gram, both printed on the label as kcal/kg.
| Current | Resting kcal | Maintenance at 1.2× | Target | Loss plan kcal | Dry grams | Wet grams |
|---|---|---|---|---|---|---|
| 3.0 kg | 160 | 191 | 2.6 kg | 115 | 30 g | 135 g |
| 4.0 kg | 198 | 238 | 3.4 kg | 140 | 37 g | 165 g |
| 5.0 kg | 234 | 281 | 4.3 kg | 167 | 44 g | 197 g |
| 6.0 kg | 268 | 322 | 5.1 kg | 190 | 50 g | 224 g |
These are starting points, not verdicts. Weigh the food on a kitchen scale for the first two weeks, because a measured cup of dry food varies by 20–30% depending on how it is scooped. Feed the daily ration in 3–4 meals, which suits a cat's natural pattern of 10–15 small hunts a day, and put the bowl down for 20 minutes rather than leaving it out.
The weighing routine that makes the score useful
Use a baby scale that reads to 10 g, weigh before breakfast, and record the number on the same day each week. A 4 kg cat losing 80 g a week is on a sensible curve; losing 200 g a week is too fast. Any loss of 2% in two weeks or 5% in a month earns a veterinary visit, and so does a score that moves two points in three months. Kitten visits booked on the vaccine calendar are the natural moments to start scoring, because a kitten's shape changes weekly and the trend is the point.
Two other situations bend the numbers. A cat with feline herpesvirus that stops eating for three days during a flare can lose 150 g of muscle and gain it back slowly over a month, so score after recovery rather than during it — the FHV long-term guide covers the flare pattern. And in a weight-loss workup, a toxoplasma titer is rarely the answer: IgG positivity is common and does not prove active disease, as the toxoplasmosis guide sets out.
When the score alone means a visit
Book an appointment for any score of 3 or lower, any score of 8 or higher, moderate or severe muscle loss at any weight, or a cat that eats normally and still loses weight. Bring the weekly weights with you, not a summary of them.
Four things to do this week
- Score the cat tonight at score 5 or not, and write the number and the date on the fridge.
- Feel the spine and shoulder blades monthly; photograph the cat from above and from the side for comparison.
- Weigh the daily portion on a kitchen scale and convert the bag's kcal/kg into grams once, then stick to it.
- If muscle is going but weight is not, book bloodwork rather than adding food.
Frequently asked
My cat is 5.2 kg and the vet says score 7. How much should it weigh?
Around 4.3 to 4.5 kg. At score 7 a cat typically carries 20–30% above ideal body weight, so dividing 5.2 by about 1.2 gives the target. Aim to lose 0.5–1% of body weight per week, roughly 50 g, which puts the whole plan at 3 to 5 months. Weigh weekly, and stop cutting calories if the cat stops eating for more than 24 hours.
Can a cat be a healthy weight and still be malnourished?
Yes. Body condition and muscle condition are separate scores, and a cat can sit at score 5 while losing muscle along the spine and temples. That pattern is common in chronic kidney disease, untreated hyperthyroidism, intestinal disease and cancer. Stable weight with dropping muscle deserves bloodwork, a T4, a urinalysis and often an ultrasound, because the scale hides the loss until about 10% of lean mass is gone.
How many grams of dry food does a 4 kg cat need per day?
About 37 g of a 3.8 kcal per gram food for weight loss, or 63 g of the same food for maintenance. The arithmetic is 70 × 4 to the power 0.75, which is 198 kcal, times 1.2 for a neutered adult, giving 238 kcal, divided by 3.8 kcal per gram. Weigh the food rather than using a cup, because scoop density varies by 20–30%.