New publication: Description of the fasted serum metabolomic signature of lean and obese cats at maintenance and of obese cats under energy restriction

We are excited to announce a new publication! Dr. Caitlin Grant and colleagues recently published their new article “Description of the fasted serum metabolomic signature of lean and obese cats at maintenance and of obese cats under energy restriction” in PLOS ONE. Read on for a short summary of their research and findings below.


The serum metabolomic signature provides us with the levels of different small molecules – metabolites or nutrients – that are circulating within the blood throughout the body. We can use these values to first, make comparisons between different physiological states or diseases and second, to make predictions about what these differences might mean. For this study, we specifically aimed to identify whether there were differences in these metabolites between lean cats and obese cats when food intake was offered to maintain their current body weight. We also wanted to gain a deeper understanding of what happens when obese cats undergo weight loss by reducing food and therefore energy intake.


This study used client-owned cats, with permission from owners that was obtained prior to the study, who were either lean or obese. The study was then divided into two phases.

In the first phase, all cats were provided with the same diet fed to maintain their body weight for four weeks and blood was collected at the end of this phase.

The second phase only included the obese cats. These cats went on to consume the same diet for 10 weeks but at an amount that would result in safe weight loss. Again, blood was collected from these cats.

Metabolites were analyzed using two different methods: Direct Infusion Mass Spectrometry (DI-MS) and Quantitative Nuclear Magnetic Resonance Spectroscopy. Although many metabolites were measured, they can be classified into various categories such as amino acids, phospholipids, acylcarnitines, etc.

Summary of Key Findings

The results of the study indicated that cats who were lean, obese, or obese but undergoing weight loss, exhibited different levels of certain metabolites. Cats appear to have different markers of obesity when compared to humans or dogs and this is likely because of the obligate carnivore nature of cats compared to omnivores.

In obese cats undergoing weight loss, the results of this study indicate that there was an increase in certain amino acids. It is hypothesized that this could mean there are changes in amino acid partitioning with weight loss. Additionally, an increase in acylcarnitines suggests that cats undergoing weight loss through calorie restriction are using fats stored as adipose tissue for energy which aids in the loss of fat mass rather than the loss of muscle.

Our findings suggest that obesity is linked to changes in metabolism and that there may be metabolic markers of obesity that are specific to cats. Additionally, calorie restriction resulting in weight loss induces metabolic changes that could support the loss of body fat mass and also alters amino acid partitioning. This research also highlights that cats in lean, obese, or calorie-restricted conditions have a different metabolic response compared to other species. Future research could help to understand these differences and to develop optimized weight loss strategies in cats – a species prone to obesity.

Blog 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

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