How Much Should You Feed Your Dog or Cat? A Science-Based Guide

Determination of Energy Requirement of Dogs and Cats

The total daily energy requirement of an animal is the sum of BMR, dietary thermogenesis, voluntary muscular activity, and maintenance of normal body temperature when exposed to adverse weather conditions. 

Dogs

Coming up with an exact formula is difficult, and we can only estimate based on some models. 

The amount of calories needed per day is directly proportional to body weight. 

In the US, the National Research Council provides a basic framework to formulate how much food to feed to dogs. 

Here are the formula for inactive dogs, along with a few calculation examples: 

Here is the formula for active dogs, along with a few calculation examples: 

These equations were provided to estimate ME (metabolizable energy) in 2006 by the National Research Council. 

It should also be noted that this is a start. A pet owner needs to adjust the amount of food based on the experience due to differences in breed or daily activity. 

Based on this, let's calculate how much pet food (3600 kcal dry kibbles per kg) to feed our pets in the example 

For instance, a 22.7 kg inactive dog requires 988 kcal per day. If this dog is somewhat active, you may increase the amount of pet food just to start with. It can be beneficial to start with 3 cups and observe your pet. You should also know that breed type makes a difference. 

We should also consider stages of life. Here is the energy requirement for different life stages: 

For Dogs: 

• The postweaned stage requires 2 times adult ME 
• 40% adult body weight requires 1.6 times adult ME
• 80% adult body weight requires 1.2 times adult ME
• Late gestation requires 1.25 to 1.5 times adult ME 
• The lactation stage requires 3 times the adult ME (see below for specific formula) 
• Prolonged physical work requires 2 to 4 times adult ME 
• Decreased environmental temperature requires 1.2 to 1.8 times adult ME 

Cats

The most mature body weight of domestic cats is between 2 and 7 kg. Because cats do not vary among breeds so much, their energy requirement is more directly proportional to their body weight. 

Due to this simplicity, we can target ideal feeding sizes for different body sizes of cats, such as lean vs. obese. 

Here is the formula for cats: 

Alternative formulas and older adult cat formulas are studied outside of the NRC. 

Here is the formula for different stages of cats: 

• Postweaned cats require 250 kcal ME per Kg of body weight 
• 20-week-old cats require 130 kcal ME per Kg of body weight
• 30-week-old cats require 100 kcal ME per Kg of body weight 
• Late gestation stage cats require 1.25 times adult maintenance ME
• Lactation-stage cats require 3 to 4 times adult maintenance ME 

Lactation stage energy requirements for dogs and cats require deeper discussions, and we will cover that area in the future specifically. 

Now you know more science-based estimations of energy requirements for cats and dogs. You must also consider your experience as well if your pet is reacting differently. This can be a change in body weight. You need to remember these formulas will give you guidelines to start. Please also provide plenty of water along with the food.