How does eating fat actually making us gain body fat?It doesn't. Your body has to do to much work to break down this fat and turn it into glucose (something we can actually use as energy). Before this process is complete it is already out of your body. The fat in meat and fatty foods don't make you fat however these fats do some other nasty unwanted stuff to your body you may want to consider. Another issue is that meat (and fat) have zero nutrition. We can actually survive perfectly well without them.
How is eating a lot of meat and fat bad for our health?When you eat a lot of fatty foods the fat will enter your bloodstream and when you do this on a regular basis it will clog up your arteries and cause heart descease and clogged arteries preventing a healthy blood flow true out your body. Diets like the Atkins diet advertise that you can eat as much meat and thus fat as you like and lose weight. While you can lose weight this way it is far from a healthy way to do it because of the reasons I just described.
Should we banish all meat and fatty foods from our diet?This is not needed. If you like to eat meat then there is no need to banish it since it doesn't make you fat however it is not advised to overdo it. One piece of meat per day is no problem while dieting and trying to lose weight.
Meat and fat are not perse unhealthy if you don't overdo things. Therefore we should be able to fit it in any diet but not to much of it. It also does nothing for your body in terms of becoming healthier.