Why It's so Hard to Cut Kitty's Calories

Analysis by Dr. Karen Shaw Becker

hangry cat

Story at-a-glance

  • A recently published study explores how calorie restriction in obese cats affects feeding behavior
  • The results suggest that calorie-restricted cats significantly change their eating behaviors, eating most of their daily allotment of food early in the day
  • Another observed behavior change was an increase in cat-cat conflicts among the calorie-restricted group
  • These behavior changes may explain why so many pet parents find it difficult to comply with recommendations to restrict their cats’ calories
  • Changing the way cats are fed can encourage natural feline hunting behaviors, provide exercise and help keep or return feline family members to a healthy weight

Estimates are that around 60% of cats in the U.S. are not only overweight, but obese. Owners of obese cats are often advised by their veterinarians to do the obvious — restrict the amount of calories kitty eats. However, this is apparently easier said than done, based on the low rate of compliance.

To try to answer the question of why it’s so difficult for cat parents to comply with recommendations to restrict how much their pets eat, scientists at Nestlé Purina Research set out to determine how much of an effect calorie restriction has on the feeding patterns of cats.

Specifically, “the objective of the present work was to better elucidate the impact of calorie cut-off on individual cat feeding behaviours, as well as on interactions between cats during food anticipation.”1

6% Reduction in Calories Has Dramatic Effect on How Cats Eat

For the study, the researchers assigned 80 domestic cats to two groups (40 per group) that were balanced for sex, age, weight, and body condition score. Cats being cats, several who “couldn’t adjust to their social group” were sent on their way, leaving 38 cats in the test group and 31 in the control group.

All the cats were fed the same commercially available diet on the same schedule. Canned food was the morning offering, kibble was served in the afternoon and overnight, along with very occasional treats. The test group of 38 cats was mildly calorie restricted (6%), which was accomplished by cutting off access to additional food when their allotted calorie intake was reached. All cats were monitored for 9 months, at which point the calorie restriction was ended.

The cats were free fed and typically consumed about 30% of their calories in the morning serving of wet food and 70% in dry food over the remainder of the day. However, the cats in the calorie restricted group quickly changed to rapidly consuming 70% of their calories in the first meal, leaving only 30% of their calories for the rest of the day. The cats in the control group, who continued to be free fed, didn’t change their eating behavior.

“While the control cats’ feeding behaviour remained unchanged throughout the trial, the study cats ate fewer but larger meals, came back faster to the food bowl after each meal, and ate their meals faster on the caloric restriction regimen compared to ad libitum feeding,” explained lead study author Séverine Ligout, PhD, in an interview with International Cat Care.

“However, one month after returning to ad libitum feeding, the study cats’ eating behaviours had returned to their baseline levels, showing that cats were able to readjust their feeding behaviours back to normal.”2

Calorie Restriction Also Increases Conflicts Between Cats

The researchers also observed an increase in conflicts between the calorie-restricted cats just before the first meal of the day. According to the researchers, it is likely linked to higher hunger and food motivation, since the cats have fewer calories to consume and they consume them faster, which leads to a longer period without food between the evening meal and breakfast the next morning.

The higher food motivation undoubtedly creates tension when several cats approach the food bowls for breakfast, leading to an increased likelihood of negative interactions. This behavior has been termed “irritability aggression” in other scientific studies and can be loosely compared to the hunger-driven irritability in humans known as “hangry” (a combination of hungry and angry).

“[The] conflicts consisted of avoidance of each other, one cat displacing another from a location by staring or approaching, lifting a paw in a threatening manner (i.e., as if to swat the other cat with its paw), and some cats actually made contact with another when swatting with their paws,” said Ligout.

“Thus, it looked like cats, just like us, are no strangers to the “hangry” (hungry + angry) feeling of hunger-driven irritability! Although no physical harm occurred during the study period, these interactions have the potential to impact negatively on the cats’ mental wellbeing and therefore welfare during the caloric restriction period, at least at actual feeding times.

These cats were housed in an enriched manner that allowed them to distance themselves from one another using space and physical structures, allowing them to avoid further conflict. In addition, their welfare was continually monitored throughout the study by veterinary professionals.”

Pet Parents Tend to Cave-in to Their ‘Hangry’ Cats

The researchers concluded that restricting the calories cats consume can change their feeding behavior significantly. Specifically, they eat larger meals faster, consuming their daily calorie allotment more quickly, which is outside the normal feline behavior of eating multiple small meals throughout the day.

So, while calorie restriction is a common strategy that humans employ when addressing feline obesity, from the cats’ perspective, it not only results in less food to eat, but also removes their sense of control over certain aspects of food availability and how much to eat.

Given that kitties like to feel in control of their living environment, it makes sense that they get “hangry” when their human attempts to restrict their food intake. According to the researchers, this leads to begging behavior, which then leads to lack of owner compliance.

Carnivores Fed Like Herbivores Results in Metabolic Confusion

Ideally, not allowing cats to free feed and become overweight is always the best advice when it comes to intentionally creating long-lived, disease-free cats. Cats, like other carnivores who remain well-muscled and lean throughout their lives, maintain innate metabolic flexibility when they’re at their ideal body weight and have periods of digestive rest in between meals.

Unlike carnivores, vegan animals (such as cows, goats and horses) need to nibble almost constantly to maintain their metabolic and physiologic wellbeing. The problem is when people feed their cats like goats, creating unhealthy and delicate metabolic butterflies that are prone to all sorts of health problems, especially when dieting.

As cats spend their days nibbling more and more, they can lose their ability to be sensitive to insulin and a variety of other metabolic hormones and end up with an overburdened liver and gallbladder and a sluggish and overworked digestive tract.

Many cats who nibble 24/7 lose their ability to effectively metabolize fatty acids at a normal rate, making them more metabolically fragile and prone to fatty liver disease (hepatic lipidosis) if they skip meals. This is the exact opposite of how nature wired cats to be — resilient, athletic, stealthy hunters who stalk their prey and take long naps in between meals.

As guardians, we often unknowingly fail cats in all sorts of ways. We feed them far too much and far too often and we feed them ultraprocessed, high carb foods, which only fuels the problem. By the time we realize we’ve created hangry addicts, it can be really difficult to switch gears. If you find yourself in this position, working with an integrative feline veterinarian or health coach who can help you map out a strategic, safe and effective plan is the best approach.

Pro Tip: Encourage Hunting Behaviors at Mealtime

The researchers recommend strategies such as puzzle feeders and/or dividing food into multiple smaller meals to help mitigate “hangry” behaviors. This advice makes sense, as wild and feral cats are always on the move in search of their next meal.

Many domesticated cats, on the other hand, are free fed at the same location every day. The more you feed, the less interested your kitty is in "hunting" — which is good exercise — around the house. If the only time you see her in motion is when she’s walking to or from the buffet, she’s getting zero exercise.

My mom adopted two older, obese cats just over a year ago. We weaned them off kibble and onto raw food in a series of small steps and very slowly, so as not to create stress. They were free fed kibble their whole lives (hence the obesity), so first we transitioned them to scheduled feedings: 6 small meals a day. Then after a few weeks we reduced them to 4 meals and then 3 meals a day.

Next we transitioned them from dry to canned food (this took about a month), then weaned them from canned food to cooked commercial food (we used Smalls), then onto raw food. The entire process took over 3 months.

Lastly, we separated their daily food allotments into several small portions at dusk and dawn and placed them in different locations around the house for them to find (we feed them in separate parts of the house while they are “hunting” to make sure they don’t eat each other’s food). I recommend making use of indoor hunting feeders, which encourage natural feline behaviors and provide mental stimulation as well.

Also consider putting food bowls or the hunting feeders at the bottom and top of as many flights of stairs as you have to encourage muscle-building exercise throughout the day.

A recent study suggesting cats may be healthiest being fed just once a day had many feline fanciers up in arms. If people suddenly cut meals for the majority of indoor, under-exercised, overfed cats all sorts of bad things can happen.

This study demonstrates the behavioral component of “dieting” cats and the correct assumption that the entire process of changing a cat’s food, food volume or feeding schedule is stressful and must be done very slowly (and patiently).

For more of my top recommendations for keeping feline family members at a healthy weight, read Crafty Ways to Slim Down an Overly Plump Cat.