The Best Cat Weight Gain Supplements

Some cats veer towards the chubby side, whereas others need some help gaining or maintaining weight. Senior cats, picky eaters, felines with health problems, and very active kitties are particularly likely to need some extra calories to help maintain their weight. So, what can you do about it? If you’ve tried increasing portion sizes with little success, we’d recommend feeding a cat weight gain supplement.

We reviewed dozens of cat weight gain supplements to identify the best of the best, focusing on a range of important factors, including nutritional value, ingredient quality, palatability, and average customer reviews.

Top Pick

Doc Roy’s Forti Cal Gel

This calorie-packed gel is tasty enough to be fed as a treat.

The stellar reviews alone were enough to make Doc Roy’s Forti Cal Gel stand out as our top pick. It’s easy to feed as a treat or mixed with food and it’s palatable enough that even a picky cat won’t turn up her nose at it.

The 5 Top-Rated Cat Weight Gain Supplements

Editor’s Picks Brand Rating
Best Overall Doc Roys Forti Cal Gel 4.8
Runner Up Vetoquinol NutriCal 4.2
Best Budget Buy Tomlyn Nutri-Cal For Cats (2-Pack)
Best Liquid Cat Weight Gain Supplement Miracle Vet High Calorie Weight Gainer for Dogs & Cats 3.4
Best Powder Cat Weight Gain Supplement Ample Nutrition Digestive Enzymes For Pets 4.3

*Ratings are from Amazon at the time of publication and can change

Our Top Pick: Doc Roy’s Forti Cal Gel

Everyone knows that cats can be picky eaters, but you needn’t worry about whether or not your furry friend will consume Doc Roy’s Forti Cal Gel. This gel tastes great, so even fussy felines will happily eat it. What’s more, costing around $15 for a pack of three, it’s actually surprisingly affordable, ounce for ounce.

You can feed this gel formulation straight off your finger or from a spoon, or you can mix it in with food. That said, the consistency of the gel means that it will be less noticeable mixed in with wet food that with dry. The correct serving size is 1.5 teaspoons per 10 pounds of your pet’s body weight (or 3 tsp per 10 pounds if your cat isn’t currently eating all of the food you provide for him), so it goes a long way with an underweight cat.

Ingredients such as pork liver, fish oil, vegetable oil, and molasses provide a calorie-dense base. However, this gel also contains a range of vitamins and minerals to promote overall health.

Doc Roy’s Forti Cal Gel Key Features: 

  • Comes as a pack of three
  • Great source of vitamins, minerals, and healthy fats
  • Suitable for kittens and adult cats

Our Runner Up Pick: Vetoquinol NutriCal

Runner Up

Vetoquinol NutriCal

With plenty of vitamins and minerals, as well as calories, this gel will help perk up underweight kitties.

If you want a tasty feline weight gain supplement to feed alongside your pet’s regular diet, Vetoquinol NutriCal is well worth your consideration. Costing roughly $12, it’s cheaper to buy than our top pick, but actually works out costing more per ounce, as you only get about a third of the amount.

You can feed it as a treat, straight from the tube, or mixed in with your pet’s meals. However, if your cat is losing weight because she won’t eat her full meals, it’s best to give an increased dose separately from her food, otherwise she won’t consume the whole lot.

Although they might not be the healthiest ingredients, substances such as molasses and malt syrup are calorie-dense and make this supplement palatable to your cat. However, we wouldn’t necessarily recommend it as a long-term weight gain solution. If your cat is consistently losing weight, your vet may be able to recommend a diet change.

In addition to these calorie-dense ingredients, Vetoquinol NutriCal contains a variety of vitamins, minerals, and Omega fatty acids, helping to make it more nutritious overall.

Vetoquinol NutriCal Key Features: 

  • Contains 28 calories per teaspoon
  • Omega 3, 6, and 9 fatty acids promote healthy skin and coat
  • Can be fed to cats of all ages

Best Budget Pick: Tomlyn Nutri-Cal For Cats (2-Pack)

Best for Budget

Tomlyn Nutri-Cal For Cats (2-Pack)

An affordable high-calorie gel with added vitamins and minerals.

Looking for a cat weight gain supplement that doesn’t cost too much? Tomlyn Nutri-Cal For Cats (2-Pack) is worth closer examination. With a price tag of less than $10 per tube, it won’t leave you out of pocket.

The malt flavor is great for finicky eaters, with the vast majority of buyers saying that their cat loves the taste. If your kitty companion won’t touch it, or you simply aren’t happy with the results, the manufacturer will give you your money back. It has a very similar nutritional profile to our runner up pick, packing in 28 calories per teaspoon, plus a range of vitamins, minerals, and healthy fats.

Tomlyn Nutri-Cal For Cats Key Features: 

  • Contains vitamins A, D, and E, plus a range of B vitamins
  • Tasty malt flavor
  • Mix with food or feed it as is

Best Liquid Weight Gain Supplement for Cats: Miracle Vet High Calorie Weight Gainer for Dogs & Cats

Best Liquid Supplement

Miracle Vet High Calorie Weight Gainer for Dogs & Cats

This liquid formula is packed with calories and healthy fats.

Containing an impressive 150 calories per ounce, Miracle Vet High Calorie Weight Gainer for Dogs & Cats will help your underweight cat pack on the pounds. With all-natural components and a transparent ingredient list, you don’t have to worry about undesirable synthetic additives or undisclosed proprietary blends.

The bulk of the calories come from fish oil and canola oil, with some whey protein in there for good measure. Alongside these calorie-rich ingredients, you have a range of vitamins and minerals to improve overall nutrition. The formula is veterinarian-approved and produced in an FDA-registered facility.

We did come across some mixed reviews regarding its palatability to cats. However, you can squirt it straight into your pet’s mount with a syringe or dropper, if they don’t like the taste mixed in with their food.

Costing roughly $25 for a 16-ounce bottle, it’s not the cheapest option out there, but a little goes a long way, so this bottle should last for some time.

Miracle Vet High Calorie Weight Gainer for Dogs & Cats Key Features: 

  • 2,400 calories per bottle
  • Veterinarian-approved formula
  • Contains a range of healthy fats, including Omega fatty acids

Best Powder Weight Gain Supplement for Cats: Ample Nutrition Digestive Enzymes For Pets

Best Powder Supplement

Ample Nutrition Digestive Enzymes For Pets

These digestive enzymes help improve nutrient absorption.

Although Ample Nutrition Digestive Enzymes For Pets isn’t a conventional cat weight gain supplement, we think it deserves a spot on our list as it can help with weight gain. If your cat eats well but still doesn’t seem to be able to put on or maintain weight (and you’ve had her checked by a vet), these digestive enzymes could hold the key.

One of their main properties is that they increase overall nutrient absorption, which means your feline friend should be able to absorb more nutrients from the same amount of food with this product added. Since your kitty will be absorbing more calories and fats, this could help her gain weight.

Containing human-grade plant- and microbial-based ingredients, this is a quality supplement that packs a nutritional punch. Due to its powder formulation, you’ll need to mix it in with your cat’s dinner, and it definitely works best when mixed with wet food, so it might not be the best choice if your pet exclusively eats dry food.

Retailing at around $25 for a 7-ounce tub, it’s one of the pricier supplements on our list, but you don’t need to use a lot.

Ample Nutrition Digestive Enzymes For Pets Key Features: 

  • Contains 9 digestive enzymes
  • Veterinarian-recommended
  • Patented BPPS (Bioactive Protein Peptide System) Technology

Who Should Buy a Cat Weight Gain Supplement

If your cat is currently underweight and needs to gain a few ounces or is struggling to maintain his current healthy weight, you might need cat weight gain supplements. Of course, your first port of call should be your feline friend’s veterinarian. Weight loss can be a result of an underlying medical problem, so you must get your pet checked over first to rule out health issues.

Other common reasons your cat might need a weight gain supplement is if she’s very active, an extremely picky eater, or she’s getting on in years. Whatever the reason for your pet’s low weight, if she needs to get some extra calories in her, you should buy a cat weight gain supplement.

Top Pick

Doc Roy’s Forti Cal Gel

This calorie-packed gel is tasty enough to be fed as a treat.

Important Features to Consider

A cat weight gain supplement should have a few important features. Here’s what to consider when selecting a weight gain supplement for your cat:

  • Calorie content. If you’re trying to get your cat to gain weight, the more calories you can get in him, the better! Many, but not all, cat weight gain supplements list their calorie content. 25 to 30 calories per teaspoon seems to be about average.
  • Vitamins and minerals. Do you simply want to fatten up your kitty or do you want to boost her vitamin and mineral intake, too? Cats who aren’t currently eating well could do with some added vitamins, but it’s not as important if your feline friend is scarfing down all her meals.
  • Healthy fats. The right kinds of fats are vital for keeping healthy and maintaining proper bodily functions. Not to mention that high-fat foods are great for weight gain! Look for cat weight gain supplements that contain decent levels of good fats, such as olive oil, canola oil, and fish oil.
  • Palatability. It doesn’t matter how calorie-dense and nutrient-rich a cat weight gain supplement is if it tastes so bad that your cat won’t eat it. Look for one that’s either highly palatable or has a neutral taste that will be disguised when you mix it with food.
  • Package size and serving size. It can be hard to tell if you’re getting a good deal with feline weight gain supplements. Compare the package size to the serving size to figure out how many servings you get for your money.

Frequently Asked Questions

What is a cat weight gain supplement and how does it work?

A feline weight gain supplement is a substance you can feed to your cat, alongside his regular food, to help him gain weight. It’s usually a gel, paste, liquid, or powder, but you can find other options out there. In the majority of cases, cat weight gain supplements are extremely calorie dense, so your cat only needs to consume a little (in addition to his regular food) to start gaining some ounces.

Will kitten food help my cat gain weight?

Kitten food contains more calories, fat, and protein than regular cat food, when compared pound for pound. As such, it can help fatten up an underweight cat.

How much should an adult cat weigh?

While it can vary depending on the breed and natural build of your cat, the majority of adult cats should weigh somewhere between 8 and 12 pounds. If you’re unsure what your cat’s ideal weight is, consult your veterinarian.

What can I feed my cat to make it gain weight?

If your cat needs to gain weight, the more calories you can get into her, the better. You can try increasing her portion sizes, but many cats will leave oversized portions. Try feeding a cat food designed for weight gain, as these will be more calorie-dense, meaning she won’t need to eat as much as a regular cat food to get the same amount of calories. In addition, feed a cat weight gain supplement and offer tasty treats between meals. If you want to ensure your furry friend is getting the best, most natural diet, check out our review of the best organic cat foods.