Lean body mass (LBM) includes skeletal muscle and organs, essentially everything except fat. It serves as an amino acid reservoir from which dogs and cats produce vital proteins such as immune cells, red blood cells and hormones.
With age, protein degradation often exceeds synthesis and this imbalance leads to progressive loss of LBM. This age-related loss of LBM, unrelated to disease, is called sarcopenia.
Sarcopenia in dogs and cats (and people) is associated with increased risk for mortality and other health problems.1
By keeping LBM loss to a minimum, cats and dogs can maintain a healthier condition and potentially live longer.
Insufficient dietary protein may contribute to loss of LBM, however there is controversy about how much dietary protein is adequate.
While cats need only 1.5g of protein per kilogram body weight to maintain nitrogen balance (protein) they need over 5 g protein/kg body weight to maintain LBM.2
Dogs require about three times more protein to maintain protein/DNA ratios (an indicator of protein reserves) compared to that needed to maintain nitrogen balance, and old dogs need 50% more protein than young dogs regardless of the measure used.3
Purina studies correlated an increase in LBM with an increased chance of survival and showed that higher protein diets can help preserve LBM and body weight in both cats and dogs.
A study of 256 cats showed they begin to lose both LBM and fat at approximately 12 years of age.4
This advanced loss of LBM, called sarcopenia, poses a risk for health problems and a shorter life span.
For “skinny old cats” every 10-gram increase in LBM results in a 2% increased chance of survival.5,6
High-protein, low-calorie diets significantly increased fat loss and reduced loss of LBM in overweight cats undergoing weight loss when compared with cats fed normal protein, low-calorie diets.7
Purina research also demonstrated that older dogs fed a high-protein diet showed slower age-related loss of LBM than dogs fed a diet lower in protein.8
Purina research with overweight dogs also showed that a high protein diet protects LBM during weight loss.
In this study, overweight dogs fed a diet with a higher percentage of calories from protein lost more fat and retained more LBM while moving closer to their optimal body condition.
Loss of LBM during weight loss is common. Since lean body mass burns more calories than fat tissue, preserving LBM may help to prevent future weight gain.
Body composition and LBM are much better indicators of overall health in dogs and cats than body weight.9,10
A body condition assessment is a focused, hands-on inquiry that veterinarians can use to evaluate the body composition of dogs and cats. Owners can also be taught the same method to monitor their pets.
Purina scientists developed the 9-point Body Condition System (BCS) for cats and dogs, which is a simple method for estimating body fat coverage and determining a pet’s optimal body condition, regardless of breed or body weight.9,10
Independently validated and published in peer-reviewed journals,11-13 this practical tool in nutritional management for dogs and cats is now used by veterinarians worldwide.