dog losing weight, 40 kg — 891–1113 kcal a day
Resting energy is 1113 kcal and the life-stage factor is 0.8–1, so the day comes to 891–1113 kcal — 254–318 g of dry food at 3.5 kcal/g.
- Body weight
- 40 kg
- Resting energy
- 1113 kcal
- Life-stage factor
- 0.8 ~ 1
- Daily calories
- 891 ~ 1113 kcal
- Daily amount (3.5 kcal/g)
- 254 ~ 318 g
- Daily amount (4 kcal/g)
- 223 ~ 278 g
- Linear shortcut
- 1270 kcal
- Gap between the two
- +14.1 %
Why the 0.75 power
Resting energy is taken as 70 × weight^0.75. Surface area does not grow as fast as volume, so a larger body loses less heat per kilogram. A 32 kg dog therefore eats eight times what a 2 kg dog eats, not sixteen times (16^0.75 = 8). Assume a straight proportion and you overfeed the big dog and underfeed the small one.
Why the factor is a range
The widely quoted tables disagree. A neutered adult dog is 1.6 in one and 1.4–1.6 in another, and weight loss splits on what the number even applies to — 0.8 of the current weight in one convention, 1.0 of the target weight in the other. Picking one number would be wrong for anyone holding the other table, so both ends are computed here.
Nearby weights
Same stage, other weights
Same weight, other stages
A starting point, not a prescription
At the same weight, real needs vary by up to 30 % with activity, breed, age, and illness. Feed at this level for a couple of weeks, then weigh and reassess. Talk to a vet for any medical condition or planned weight loss — cats in particular must never drop their intake abruptly.
How to read this
- Resting energy = 70 × weight to the power 0.75. It is not proportional to weight.
- Daily calories = resting energy × life-stage factor. Tables disagree, so a range is shown.
- Grams = daily calories ÷ the kcal per gram printed on the bag.
- Feed for two weeks, then weigh again. This is a starting point.
Frequently asked questions
Q. How much should a 40 kg dog losing weight eat?
891–1113 kcal a day — resting energy of 1113 kcal times a life-stage factor of 0.8–1.
Q. How many grams of food is that?
254–318 g at 3.5 kcal/g, or 223–278 g at 4.0 kcal/g.
Q. What does the linear shortcut give?
30 × 40 + 70 = 1270 kcal, which is above the 1113 kcal exponential figure by 14.1 %.
Q. Can I take this number as final?
Use it as a starting point. Real needs vary by up to 30 % with activity and age — feed for two weeks, then weigh again.