Why is my cat losing weight? | Ziwi Pets
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Why is my cat losing weight?

Is your cat losing weight but still eating normally? Or have they suddenly lost all interest in food, without an obvious explanation?

Both situations can be cause for concern - and recognizing a potential problem is the first step in getting your cat’s health back on track. 

Let’s take a look at some of the possible reasons behind your cat’s weight loss and explore the optimal diet that will help them maintain a healthy weight at every age. 

Is your cat losing weight? This could be why 

There are many factors that affect your cat’s weight, including:

  • Age and breed - some cats are naturally more lean than others, and older cats are less active so they tend to eat less as their metabolism slows down. 
  • Poor diet, illnesses & digestive issues  - nutrient deficiencies, intestinal parasites, diabetes, Irritable Bowel Syndrome (IBS) and Inflammatory Bowel Disease (IBD) wreak havoc on your cat’s body and their ability to maintain a healthy weight.
  • Lifestyle - is your cat stressed or anxious? Are they getting enough exercise? Are they a picky eater? There are lots of lifestyle and environmental factors to consider.
  • Dental health - the pain associated with unhealthy gums and teeth can affect a cat’s appetite.
  • Competition - does your cat live with other pets? If so, is it possible these furry roommates are getting to the food before your cat? Cats that live in households with another cat or dog may compete for food, so try feeding them in separate locations.
  • Hyperthyroidism - older cats (8+ years) are more at risk of this disease in which there’s an overproduction of thyroid (a hormone responsible for regulating many body processes), resulting in weight loss despite regular or increased eating.

The best type of food (and quantity of food) for weight gain will depend on your individual cat, but since the cause and cure of many health issues is nutrition - let’s start with getting the basics right!

What’s the best cat food for weight gain?

Cats need a moisture-rich, nutritionally balanced, species-appropriate diet to thrive. If they’re eating the diet they were biologically designed to eat (one with lots of meat!), they are more likely to maintain a healthy weight and avoid most health issues. 

If your cat’s diet consists mainly of processed food, switching them to ZIWI Peak is a great first step to help them gain weight. All ZIWI Peak recipes mirror authentic levels of meat, bone, organs, and natural fats that cats would eat in the wild - which takes the guesswork out of finding and combining the right ingredients and ratios.

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If you’re dealing with a fussy cat, switching them to a new diet isn't an overnight solution. Cats can be suspicious of change, and are known to protest new foods by fasting. 

The good news is that a small amount of nutrient-dense food, like ZIWI Peak, goes a long way. So, even if they start by eating a little, the nutritional benefits are huge!

Patience and persistence 

To help your cat gain weight safely, we recommend a ‘slow and steady’ approach. An accurately measured, gradual increase in food will allow your cat’s digestive system time to adjust (without the harsh side effects, like a sensitive stomach). 

Simply follow these 4 steps:

  1. Choose a ZIWI Peak recipe (either air-dried or wet)
  2. Slowly start transitioning to the new ZIWI diet (check out our transitioning guide for tips) 
  3. Start feeding your cat 10% more than the recommended feeding amount for its body weight (use our handy feeding calculator here) 
  4. As they start to gain weight, recalculate the feeding amount (plus 10%) to their new weight. Do this again and again until they reach their ideal weight, then continue feeding your cat this amount of food ongoing. 

Before you transition to a new diet, you could also consider a ‘single protein’ approach. This means starting with a single protein that your cat is familiar with. Once they become comfortable eating a single recipe, you can slowly start to add another. 

If you choose to feed your cat a species-appropriate diet (like ZIWI Peak, which is suitable for cats of all ages and is carefully crafted to mirror the meat-rich diet they require for a happy, healthy life), they’re less likely to suffer from any concerning issues associated with weight loss. On the other end of the spectrum, an optimal diet also means they’re less likely to become overweight (another major cause for concern) - so it’s a win-win!

If you’re not already doing so, it’s also a good idea to weigh your cat regularly. Even if they’re perfectly healthy - the closer you keep an eye on their weight, the more likely you are to catch any issues before they have a chance to progress. 

If you have any questions about transitioning your pet to ZIWI Peak or calculating their feeding requirements, please get in touch with our team. 


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ZIWI Peak air dried pet food for dogs and cats close up

Gently air‑dried

Air Dried pet food

A modern take on centuries‑old meat preserving techniques, our Z-TWINTECH® air drying technology locks in the goodness of our raw ingredients, creating ready-serve raw-inspired nutrition.

ZIWI Peak - ethical and sustainable ingredients source from the land and sea of New Zealand

Ethical & Sustainable Ingredients

Our free-range, grass-fed meats and local poultry are ethically raised under New Zealand’s Freedom Principles, while our sustainable seafood comes from the world’s top-ranked fisheries.

Chopping board of raw ingredients

PeakPrey® Recipes

Crafted for peak nutrition, with high inclusions of meat, organs, and seafood in authentic PeakPrey® ratios – with added superfoods for a nutritional boost.

Air-Dried Scoop & Serve
Free-Range Farming
Ziwi Peak pet food with no grains
No Grains Sugars or Glycerins Added
Raised Without Added Hormones or Growth Promotants
Air-Dried Scoop & Serve
Free-Range Farming
Ziwi Peak pet food with no grains
No Grains Sugars or Glycerins Added
Raised Without Added Hormones or Growth Promotants