In addition to the known health risks associated with overweight and obese pets, these conditions also impact – and are impacted by – the microbiome.1
The physiological processes involved in overweight and obesity are complex,1,2 and the gut microbiome plays a dynamic and integral role in both the development and management of these health conditions.
The microbiome of obese dogs exhibited differences in some bacterial species, but major shifts in the microbiome were not detected.3,4
The gut microbiome of overweight (BCS 6/9) beagles showed reduced alpha diversity and higher abundance of Fusobacteria compared to leaner dogs.5
Overweight and obese cats had different microbiome composition compared to lean cats fed the same diet.6-8 The alpha diversity (within sample) was not significantly different, but the beta diversity (between groups) differed.6
Overweight/obesity is associated with shifts in the bacterial populations of the gut microbiome in cats and dogs. However, it remains to be determined if these shifts represent cause or effect.
Obese beagles fed a hypocaloric, low-fat, high-fiber dry diet lost weight and showed increased microbiome diversity at the end of a 17-week trial.9
The microbiome of cats was altered with weight loss, with increases in Actinobacteria and lower Bacteroidetes.7 No changes in diversity indices were observed before and and after weight loss in obese cats.6
Some research suggests the bacterial populations of the gut microbiome are altered by weight loss, while others have shown less effect. This may represent differences in study design (including diet) or individual variation.
Obese dogs experience larger shifts in the microbiome in response to dietary changes.10
Obese cats experience larger shifts in the microbiome in response to dietary changes.8
This may indicate that their microbiome is less stable than that of healthy-weight dogs and cats, but it could also present opportunities for nutritional intervention to improve weight management
The composition of the microbiome may impact the ability to lose weight in dogs, and some dogs have a microbiome that could make them more resistant to weight loss. Changes in the abundance of some microbes were correlated with the rate of weight loss in obese pet dogs fed a high protein, high fiber diet.12
Metabolic products of the enteroendocrine cells in obese cats were altered in response to reduced caloric intake and weight loss – including an increase in the production of glucose-dependent insulinotropic peptide (GIP), which increases insulin sensitivity of adipose tissue and promotes obesity.13
Weight loss in pets is complicated, and maintaining weight loss or decreasing the tendency to regain weight can be difficult. Every pet’s weight loss journey is individual.
The ratio of dietary protein to carbohydrates had a more significant impact on the gut microbiome in obese dogs than in lean dogs.10
The microbiome of obese dogs fed a high protein, low carbohydrate diet (as opposed to those fed a diet lower in protein and higher in carbohydrates) more closely resembled the microbiome of lean dogs.10
Increasing dietary protein had a greater overall impact on the fecal microbiome in obese dogs compared to lean dogs.14
The ratio of dietary protein to carbohydrate influences the gut microbiome, and this effect was more pronounced in overweight cats. Metagenomics showed that pathways involved in energy and one-carbon metabolism were altered in overweight/obese cats fed diets with different ratios.8
Enhancing the microbiome toward a more favorable (lean) type may provide opportunities for improved weight management approaches for dogs and cats.