The Secrets of Feline Feeding: Why Giving Your Cat More Can Do Less?

Cat owners who overfeed their beloved felines may be harming them without realizing it. Beyond the extra pounds, a new study found that overfeeding your cat can also reduce nutrient digestion and cause changes in its gut microbiota.

This finding supports researchers’ advice that pet owners should limit food intake and encourage their feline companions to stay active.

More than half of cats in the United States are overweight, which is concerning enough on its own. Weight loss in cats has been widely studied, but the University of Illinois Urbana-Champaign team wanted to better understand the impact of weight gain.

“Until now, little attention has been paid to the opposite process, which is also important,” says Kelly Swanson, a nutritional scientist and the study’s lead author. “We wanted to learn more about the metabolic and gastrointestinal changes that occur as a result of overfeeding and weight gain in cats.”

Their research involved 11 “lean” cats, all of them spayed adult females. The cats received a balanced, measured diet for two weeks while Swanson and his colleagues took baseline measurements. Then, for 18 weeks, the animals were given the same type of food but allowed to eat as much and as often as they wanted.

At the start, and again at 6, 12, and 18 weeks after the all-you-can-eat feast began, the researchers collected stool and blood samples, as well as data on unrestricted physical activity through monitors placed on the cats’ collars.

“We expected weight gain might lead to decreased physical activity, but we did not observe consistent changes in activity levels,” Swanson says. “However, this could vary depending on the individual cats and their environment, and how much their owners interact with them.”

The cats wasted no time increasing the amount of food they consumed once they were allowed to do so and, as expected, gained weight. As the cats ate more and grew larger, their body fat levels increased and their ability to digest nutrients decreased.

“When the body receives less food, it becomes more efficient at extracting nutrients. But when the amount of food increases, it passes through the digestive system faster and fewer nutrients are extracted in the process,” Swanson explains.

With more food, the cats also defecated more and produced more acidic stools, a sign that the food was not being digested effectively.

“In humans, a low fecal pH indicates poor carbohydrate and fat absorption. Our findings align with this, as a reduced fecal pH corresponded with greater food intake and reduced digestibility,” Swanson explains.

The researchers found differences in the types of microbes living in the cats’ intestines before and after 18 weeks of free feeding. In addition, gastrointestinal transit time—basically, the time from eating to defecating—decreased by approximately 25 percent as the cats gained weight.

“The change in gastrointestinal transit time was a novel finding and a potential reason for the change in the fecal microbiota,” Swanson says.

Importantly, some changes in the microbiome of the cats studied were contrary to those observed in people with obesity, indicating that more complex factors are likely at play than weight alone.

Understanding the metabolic and gastrointestinal changes that occur with obesity in cats could help prevent and treat it, and the team suggests that future research could take a closer look at how changes in the gut microbiome relate to overall health.

Along with other researchers, Swanson and his colleagues demonstrated in another study that limiting cats’ food intake can help them safely lose weight and body fat.

And when the weight-gain study ended, all 11 cats were placed on restricted diets that allowed them to return to their baseline levels.

In addition to feeding cats only what they need, the authors suggest that pet owners take steps to encourage physical and mental activity at mealtime. They can divide food into small portions placed in different locations, toss food for cats to retrieve, and use food puzzles.

Cats are intelligent and do not seem to enjoy being told what to do, but it appears that our often-independent companions can lead healthier and happier lives with the right interventions from us. So let’s feed our cats sensibly, keep them active, and remember that our furry friends depend on us to keep their tails held high—or, in this case, to make their whiskers tremble with joy.