Fat cats on a diet shed light on human obesity

A recent study suggests that pet cats could serve as excellent models for researching the origins and treatment of obesity in humans. This is due to similarities in gut microbiome changes related to diet observed in both species. 

The research involved analyzing fecal samples from obese cats as they underwent dietary changes, including strict calorie reduction. 

Food-related alterations in the gut

The findings revealed that food-related alterations in the cats’ gut microbiome were remarkably similar to those seen in humans.

“The gut microbiota comprises a dynamic community of microbes within the intestinal tract that influences their host in states of health and disease through production of microbial-derived metabolites,” wrote the study authors.

“In people, deviations from the normal microbiota and alteration of microbial-derived metabolites, including short-chain fatty acids (SCFAs), are well-demonstrated in the context of obesity and are influenced by diet.”

The experts noted that recent research aims to pinpoint specific drivers of these interactions with meta-analysis revealing significantly greater amounts of the SCFAs acetate, butyrate, and propionate in feces from obese people compared to non-obese controls.

Obesity and gut microbiota 

According to the scientists, investigating the relationship between gut microbiota and obesity in cats could shed more light on how such interactions occur in humans. 

“Animals share our beds. They share our ice cream. There are all these things that people do with their pets that highlight they are a naturally occurring disease model with similar environmental exposures as humans,” said lead author Jenessa Winston, an assistant professor of veterinary clinical sciences at the Ohio State University. 

This makes cats a promising model for studying microbiome-directed therapeutics for obesity in humans.

Obesity in cats and humans

The study found that 60% of cats are obese or overweight in developed countries. Similarly, over 40% of adults in the United States are obese. 

Winston’s lab focuses on harnessing the therapeutic power of microbes to combat obesity. She oversees clinical trials exploring the potential for fecal transplants from lean to overweight pets.

Focus of the study

The study involved feeding seven obese cats a four-phase diet over 16 weeks, with phases including free-feeding commercial cat food, a weight-loss diet, calorie-restricted feeding to achieve weekly weight reduction, and a return to the original diet. 

The researchers analyzed fecal samples to track changes in short-chain fatty acids, metabolites produced by gut bacteria during digestion. 

These acids are significant because they mediate communication between gut microbes and other body tissues, influencing inflammation and insulin resistance.

Dietary change and gut bacteria

A key finding was the increase in propionic acid, a short-chain fatty acid linked to appetite regulation, fat reduction, and protection against obesity and diabetes. 

The rise in propionic acid during the calorie-restricted diet correlated with increased presence of the bacterium Prevotella 9 copri. This bacterium has also been associated with weight loss and better blood sugar control in humans.

“When the cats are on the special diet formulated for weight loss, propionic acid goes up and stays high, and then goes back down when they’re put back on the maintenance diet. So it really is a dietary change,” Winston explained. 

This indicates that calorie restriction in obese cats alters their microbial ecosystem, potentially correlating with metabolic outcomes.

Cats as models to study obesity

The study underscores the potential of using cats as models for understanding obesity in humans. 

The parallels observed in microbiome changes between cats and humans highlight the promise of developing microbiome-based therapies for obesity. 

While the precise role of the gut microbiome in obesity remains unclear, decades of evidence suggest these organisms and their metabolites are part of the complex disease mechanism.

These findings could pave the way for new treatments for obesity, benefiting both human and feline health. 

The study, published in the journal Nature Scientific Reports, demonstrates the value of pet cats in obesity research, given their similar environmental exposures and the ability to observe significant microbial and metabolic changes in response to diet.

“In summary, caloric restriction-induced weight loss in cats alters the gut microbial community structure to a state that promotes the microbially-derived metabolite propionic acid,” said the researchers.

The role of the gut microbiome in weight loss

The experts noted that the change in microbial community occurred as a direct result of diet as well as likely changes in host-related mechanisms that shift during weight loss and remain to be further identified and studied. 

The bacterial species Prevotella 9 copri was found to significantly positively correlate with increased fecal propionic acid, a microbial metabolite characterized in other mammalian species within the context of obesity and type 2 diabetes, the researchers added. 

“This cross-species conservation of findings highlights the potential application of obese cats as a translational model to further investigate the role of the gut microbiome and microbial-derived metabolites in the context of obesity and type 2 diabetes aimed at improving feline and human health.”

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