Switching from puppy food to adult dog food

Puppies and adult dogs are not the same animal, nutritionally speaking. A puppy in the first months of life is simultaneously building a skeleton, growing muscle, and developing organ systems. That takes a very different fuel mix from what a healthy adult dog needs to simply maintain condition. Getting the timing of the switch right matters more than most owners realise, and getting it wrong in either direction causes real problems.

What actually makes puppy food different

Puppy food is not just adult food with a different label. The formulas are genuinely distinct. FEDIAF, the European body that sets nutritional standards for pet food, recommends a minimum crude protein content of 22.5% on a dry-matter basis for growth-phase diets. Adult maintenance only needs to hit 18%. [1] Calcium and phosphorus are also higher in puppy food, supporting the rapid mineralisation of developing bones.

Feed adult food too early and a puppy may fall short of those higher demands. The reverse risk is less obvious but equally real: large-breed puppies fed high-calorie diets can grow too fast, placing load on joints before they are ready for it. For giant breeds especially, energy density matters as much as protein content.

When to switch, by breed size

There is no universal answer, because the timeline depends almost entirely on how large your dog will be as an adult. FEDIAF classifies physical maturity by expected adult body weight:

• Small and medium breeds (up to around 25 kg): typically ready for adult food at 12 months
• Large breeds (25 to 45 kg): usually between 12 and 15 months
• Giant breeds (over 45 kg): often need puppy or junior food until 18 to 24 months [1]

Age alone is an unreliable guide. A 14-month-old Labrador may still be maturing while a Miniature Dachshund of the same age has been fully grown for months. If you are unsure, your vet can run a body condition score check, which gives a more reliable answer than guessing by age.

How to make the transition without digestive upset

Abrupt food changes commonly cause loose stools. The gut needs time to adjust to a new protein source, fat profile, and fibre content. A 7-to-10-day gradual transition reduces that risk:

• Days 1–3: 75% old food, 25% new food
• Days 4–6: 50% old, 50% new
• Days 7–9: 25% old, 75% new
• Day 10: fully on the new food

Some dogs handle it in a week. Others need two. Softer stools are the clearest sign the transition is moving too quickly; slow down rather than pushing through.

What to look for in a good adult formula

Start with the label. "Complete and balanced" means the food meets established nutritional standards for adult maintenance without supplementation. A named protein source near the top of the ingredient list is a better sign than a vague category like "meat and animal derivatives."

Kibble size also matters more than most people think. Small dogs eating oversized kibble tend to swallow pieces without chewing efficiently, which slows digestion. IMBY's insect-based dog food comes in three adult kibble formats matched to body weight range: Mini (up to 10 kg), Medium (10 to 35 kg), and Maxi (over 35 kg). The same range includes a Puppy variant and a Senior variant, so if your dog is already on the insect-based formula, the transition is simply a matter of switching to the right variant rather than introducing an entirely new protein source.

For dogs that react to animal proteins, IMBY's plant-based formula provides complete adult nutrition without animal-derived ingredients. Dogs are omnivores and can thrive on a well-formulated plant-based complete food.

Weight management starts here

The switch to adult food is when portion control starts to matter in a new way. Puppy food is calorie-dense by design. Adult food is less so, but owners often keep feeding the same volume as before and miss the weight gain for months.

Studies in veterinary practice consistently find that between 25% and 40% of dogs are overweight. [2] One large US survey put the figure as high as 59%. [3] The consequences are well-documented: excess weight accelerates joint degradation, raises the risk of metabolic disease, and shortens lifespan.

After switching to adult food, weigh your dog every few weeks for the first couple of months. If the number is going up, reduce the daily portion by 10% and reassess before blaming the formula.

When it is time to switch again

Older dogs have different needs. Activity tends to decrease, digestive efficiency drops slightly, and the risk of joint problems climbs. Senior formulas address this with more easily digestible proteins and lower calorie density.

Not every older dog needs a senior food, though. One in good body condition on a quality adult formula can do fine, and switching for the sake of it does not automatically help. The decision is worth a conversation with your vet, particularly if weight is creeping up or the dog has noticeably slowed down. IMBY's senior variant is designed for dogs from nine years old, using the same insect protein base as the adult food.