How much to feed
My dog is underweight, how much more should I feed to help it gain?
Last updated 23 September 2026 · How we write and check this
Short answer
Start by increasing daily food by around 10 to 20 percent above the standard calculated amount for your dog's current weight, then reassess every two weeks based on how the body condition responds, increasing further in similar steps if needed. Avoid a very large sudden increase, since a dog that has been undereating can have a sensitive digestive system that benefits from a gradual ramp up.
Starting the increase gradually
Calculate the standard amount for your dog's current weight using the resting energy formula, then add 10 to 20 percent as a starting increase, rather than jumping straight to a large portion.
If your dog has been significantly underweight for a while, discuss a specific plan with your vet first, since reintroducing food too quickly after a period of undereating can cause digestive upset.
Choosing the right food for weight gain
A higher calorie density food can help a dog gain weight without needing an uncomfortably large volume at each meal, particularly useful for a dog with a smaller appetite.
Splitting the increased amount across three or four smaller meals a day, rather than two large ones, often suits a dog building its appetite back up better than fewer, larger meals.
Tracking progress
Weigh every two weeks and check body condition alongside the number on the scale, since the goal is a healthy covering over the ribs and a visible but not exaggerated waist, not simply the highest weight possible.
Increase the amount further in 10 percent steps if weight gain is slower than expected after a month, and involve your vet if progress stalls or your dog does not seem to be gaining at all. A vet can also check for an underlying reason a dog might struggle to gain weight despite an adequate food increase.
Key takeaways
- Start with a 10 to 20 percent increase above the standard calculated amount for current weight.
- Increase gradually rather than jumping to a large portion, especially for a dog that has been undereating.
- A higher calorie food or smaller, more frequent meals can help a dog with a reduced appetite gain weight comfortably.
- Check body condition alongside the scale number, aiming for a healthy covering rather than maximum weight.