Dietary lysine: Calorie ratios and their influence on nitrogen metabolism and digestibility in moderately obese mature dogs

Problem statement: A goal during weight loss is to reduce body fat while maintaining body protein. We hypothesized that an increased dietary lysine: calorie might be beneficial during periods of caloric restriction. Approach: Two experiments were conducted to determine if changing the ratio of lysine: calories (lysine g/kg: Mcal ME/kg) while maintaining an ideal profile of amino acids will change nitrogen metabolism and weight loss in obese mature dogs. Results: The results of these experiments imply that if all essential amino acids are in adequate supply in the food, foods with an optimal balance of nutrients can reduce muscle degradation during periods of caloric restriction. Conclusion: Our optimum food for decreasing protein degradation was the food containing 3.0 lysine: calorie. However, the present experiments were relatively short and these results may not be sustained over longer periods of restriction.