@Dek No disrespect to your brother and 3 friends, but the frog will have some organ failure later on in his life. All things to be considered is it's a slow process until one of the above symptoms displays. It could be 1-7 years before the frog would end up dying from this type of diet. As the kidney & liver break down proteins, the mammalian-fat tissue from the vertebrate slows the process down blocking the digestive enzymes from doing their job. That's why it's not good for us humans to eat a lot of red meat as a regular diet.

Frogs display abnormal behavior, obesity, complications, and completely stop eating when complications arise. Listen to their advice and only feed vertebrates once a month maximum. Vertebrates (with a backbone) would rarely come across these frogs diets in the wild if not any at all for the first couple of years of their life. Their diet mostly consists of invertebrates (without a backbone) that provides enough nutritional value and can be broken down as a regular staple diet for these frogs. Hope I helped.