Because of fast food chains, your body sends signals to the brain with the chemicals in the food making your body think it taste better than what it does. So therefor people don't know how to stop eating even when they are full and all the sodium and sugar causes bad health issues do to their food.
As much as I want to say, no, the fast food industry should not be held responsible for health issues, the truth is, someone has to be. Unfortunately, in the world today it is cheaper to buy a dollar burger than it is to get a healthy salad. If the opposite were true then more people would pick healthier food choices. Until unhealthy food items cost more than healthy food items, health issues are going to continue to go up. The fast food industry could easily prevent some of this by modifying their menus. They can offer the unhealthy options, but do so at a higher price and lower the price of the more healthy options.
Many of the poor in the world use fast food as a cheap and easy way to eat. As do people who do not have a lot of time to prepare their own meals (they also tend to be poor or middle class). For this reason they should provide enough health information for the people they are serving.
I do not believe that fast food industries should be held responsible for health issues. I assume we are speaking about the status of the health maintained in the food and how it lacks real nutrition. I believe these companies have provided a service and they have not forced anyone to eat their food. People choose fast food because they want it, rather it causes bad health or not.