Do male rats attack female rats?

Male rats can be far larger then females. Female rats range from around 250 grams to 450 grams. Males range from around 400 grams to 700 grams. Female rats are not usually as muscular as males and often have smaller heads and feet. However some rats are prone to weight gain. If when your rat sits, you cannot see definition in their body, such as they look just like a ball, instead of having definite legs , they are most likely over weight.