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With the holiday season approaching, many of us think about our waistlines and dieting. Some will start dieting before the holidays to fit into those party clothes. Others will contemplate strategies for eating during the holidays to minimize gain with the goal to lose those extra pounds after the holidays. You know, the proverbial “New Year’s Resolution.”

All-in-all concerns about our weight create much angst during this joyous time of year. This got me to thinking about obesity and weight loss in pets. In particular, I was reminded of two oral presentations at the 2014 Academy of Veterinary Internal Medicine Symposium in Nashville, Tennessee, about weight loss strategies for cats.

Chronic Calorie Reduction

Chronic calorie reduction is a weight loss strategy based on restricting calories at a calculated level and maintaining or reducing that level of calories until a cat achieves its ideal weight.

In this particular study, 32 client owned, obese cats were evaluated by a sophisticated X-ray technology (Dual-Energy X-ray Absorptiometry or DEXA) to determine their ideal body weights (IBW). The cats were then put on a diet that delivered 80% of the calories necessary for their resting energy requirement, or RER.

RER is the absolute minimum number of calories necessary for body function at complete rest; not the amount of calories needed for maintenance energy requirement (MER) that includes normal, regular daily activities. The cats were fed this way until they reached their IBW, or until 104 weeks (2 years), whichever came first.

Twenty-six percent of the cats left the study early due to owner non-compliance. Owner relocation, cat aggression to researchers, and other medical reasons caused another nine cats to drop from the study.

Of the seventeen cats that finished the study, thirteen (76%) achieved their IBW within the first year. Three other cats achieved IBW in the second year, and one cat did not achieve IBW in the time period.

Calorie adjustments during the testing period varied from as low as 40% of RER calories to as high as 100% of RER calories based on periodic weight monitoring. Periodic blood testing ensured the safety of the diet for the cats.


Intermittent Calorie Restriction

Intermittent calorie restriction is a weight loss strategy where animals are calorie restricted part of the time and fed normally the other times.

In this study, 28 laboratory cats were divided into two equal groups. Fourteen cats were fed 75% of their estimated MER for six months. The other fourteen cats were fed 75% of their MER for the first two weeks of the month and then 100% of their MER for the second two weeks for twelve months. These cats were fed longer so that their calorie restricted period matched the period for the group that was chronically restricted for six months. Weekly body weights and monthly body scans for body fat were performed on all cats throughout the study period.

The researchers found that the intermittent group lost more body fat than the chronically restricted group. They also found that 82% of the intermittent group achieved IBW in the time period versus only 36% of the chronic restriction group.

My Take

After hearing the presentations and questioning the primary investigators, I am intrigued by the intermittent strategy as a more effective program for two reasons:

It has the potential for decreasing the metabolic changes that occur during dieting that promote weight regain after dieting. This may mean that cats can be fed a more satisfying amount of calories after dieting.

Presently, those cats and dogs that lose weight on chronic calorie restrictions are only able to ingest 10% more calories after their diet (anecdotal evidence from researchers and my own clinical experience).

More importantly, owner compliance may be better if there is not the perception of starving their babies. Certainly more research is needed to address these concerns.

Some human research has yielded the same results with intermittent calorie restriction. Perhaps this is the way we should strategize for the holidays for ourselves and our pets. Happy Holidays!

Dr. Ken Tudor


Weitzel A., Paetau-Robinson I, Kirk C Successful weight loss in severely obese cats. Ahead of publication

Pan Y Intermittent caloric restriction is more effective than chronic caloric restriction in promoting weight loss in overweight cats. Ahead of publication

Image: Andrey_Kusmin / Shutterstock

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