How Exercise Affects Your Pet’s Nutrition Needs

A Border Collie herding sheep for eight hours and a Bulldog napping on the couch have dramatically different nutritional needs, even if they weigh exactly the same. Activity level is one of the most important factors in determining how much and what to feed your pet, yet most feeding guides on pet food bags only distinguish between "active" and "less active" — a simplification that misses the nuance of real-world energy expenditure.

Activity Categories and Calorie Multipliers

Veterinary nutritionists categorize activity levels based on daily energy expenditure relative to resting energy requirements (RER):

RER (resting energy requirement) in kcal = 70 × (body weight in kg)^0.75. For a 20 kg dog, RER is approximately 660 kcal. A sedentary 20 kg dog needs about 790-925 kcal daily, while the same dog doing heavy work might need 1,320-3,300 kcal.

Protein Needs Scale With Activity

Active muscles require more protein for repair and maintenance. Sedentary dogs do fine with 18-22% protein (dry matter basis). Moderately active dogs benefit from 22-28%. High-performance working dogs, sled dogs, and agility competitors perform best on 28-35% protein with emphasis on animal-source amino acids.

For cats, protein needs are less affected by activity because cats are obligate carnivores with inherently high protein requirements (minimum 26% DM for adults, ideally 30-45%). Active cats may need slightly more total food rather than a higher protein percentage.

Fat: The Primary Fuel for Endurance

During sustained exercise (over 30 minutes), dogs rely primarily on fat metabolism for energy. This is why working dog and sport dog formulas are high in fat (20-35% DM). Fat provides 2.25 times more calories per gram than protein or carbohydrates, making it the most energy-dense macronutrient.

For short-burst activities (agility, flyball, sprint training), carbohydrates become more important because anaerobic metabolism (which powers explosive movement) relies on glucose rather than fatty acids.

Hydration and Electrolytes

Active pets lose water through panting (dogs), evaporation, and sweat (through paw pads). A dog exercising in warm weather may need 2-3 times their resting water requirement. Offer water every 15-20 minutes during sustained activity, and do not wait for your dog to show signs of thirst — by the time panting becomes excessive, dehydration is already underway.

Electrolyte supplementation (sodium, potassium, chloride) may benefit dogs during extended exercise in heat but is unnecessary for typical daily activity.

Timing Meals Around Exercise

• Before exercise: Feed a small meal 2-3 hours before strenuous activity, not immediately before. Exercising on a full stomach increases the risk of bloat in deep-chested breeds.
• During exercise: For activities lasting over 2 hours, offer small snacks and water at regular intervals.
• After exercise: Wait 30-60 minutes after intense activity before offering a full meal. Provide water immediately but in controlled amounts (gulping large volumes risks bloat).

Adjusting for Seasonal Changes

Most dogs are more active in spring and autumn (comfortable temperatures) and less active in summer heat and winter cold. Pay attention to actual activity levels rather than following a fixed feeding amount year-round. If your dog's exercise drops significantly during a heat wave or cold snap, reduce portions proportionally.