We are excited to announce a new publication! Hannah Godfrey and colleagues recently published their new article “Isoenergetic reduction of dietary macronutrients affects body composition, physical activity, and post-prandial hormone responses in lean and obese cats fed to maintain body weight” in Frontiers in Veterinary Science. Read on for a short summary of their research and findings below.
Objective
The purpose of our study was to understand how different diets affect body composition, physical activity, and hormone responses in lean and obese cats. We wanted to find out if changing the amount of protein, fat, or carbohydrates in their diet would make a difference when the cats were fed to maintain their body weight.
Methods
We conducted an experiment with 9 lean and 9 obese cats. The cats were fed one of three different diets over 4 weeks, with the following distribution of macronutrients presented as the percent of metabolizable energy:
- Low-Protein (LP): 28% ME protein, 40% ME fat, 32% ME carbohydrates
- Low-Fat (LF): 40% ME protein, 30% ME fat, 30% ME carbohydrates
- Low-Carbohydrate (LC): 36% ME protein, 41% ME fat, 23% ME carbohydrates
After the 4 weeks, we measured their body composition, physical activity, and we analyzed their serum satiety hormone levels before and after their meal.
Findings
All cats tolerated the different diets well with no adverse effects and maintained body weight throughout the study.
- Body Composition: Cats on the LF diet had more lean soft tissue mass compared to those on the LP and LC diets. This was likely due to two things. First, since there were more carbohydrates compared to the LC diet, this could allow for more glucose to be stored as a readily available energy source in the muscle as glycogen. Second, more carbohydrates for energy would allow for amino acids coming from the higher protein content in the LF diet to be used for muscle mass synthesis in these cats.
- Physical Activity: There was no significant difference in overall physical activity between lean and obese cats. However, cats on the LP diet were less active during the night.
- Hormone Responses: All cats showed a decrease in the hunger hormone ghrelin after eating. Cats on the LC diet had lower ghrelin levels and higher levels of the satiety hormone PYY after meals. This could mean that cats were more satiated following the LC diet, suggesting that protein and fats induce a greater satiety effect than carbohydrates.
Conclusion
Our findings suggest that cats are quite adaptable to different diets as long as their nutritional needs are met. The LF diet may help increase muscle mass, while the LC diet could improve satiety and reduce hunger.
Key Take-Aways
From the literature and our study, there is no clear consensus on the best diet for cats. Some studies suggest high-fat diets lead to weight gain, while others find no significant impact of carbohydrates on body fat. Our study supports the idea that cats are metabolically flexible and can adapt to different macronutrient distributions. Specifically:
- High-Protein, Low-Fat Diets: May help increase muscle mass, as seen with the LF diet in our study.
- Low-Carbohydrate Diets: Could improve satiety and reduce hunger, as indicated by lower ghrelin and higher PYY levels in cats on the LC diet.
- Physical Activity: Lean and obese cats showed similar levels of physical activity, suggesting that a reduction in physical activity could be due to longer-term obesity in cats, rather than early indicator of obesity.
Future Directions
Future research should explore the long-term effects of these diets on cats, especially during weight loss programs. Understanding how different nutrients affect cats over a longer period could provide more insights.
This study was supported by the Natural Sciences and Engineering Research Council (NSERC) Alliance Grant and Mitacs Accelerate, in partnership with Champion Petfoods Holdings Inc.
Interested in similar research?
- New Publication: Isoenergetic reduction of dietary macronutrients modulates respiratory quotients and heat increment of feeding but not energy expenditure in cats
- New Publication! A meta-analysis: Dietary carbohydrates do not increase body fat or fasted insulin and glucose in cats
Written by: Hannah Godfrey, BSc.H., MSc., PhD Candidate
Reviewed by: Dr. Adronie Verbrugghe, DVM, PhD, Dip ECVCN, Associate Professor and Royal Canin Veterinary Diets Endowed Chair in Canine and Feline Clinical Nutrition