|MadSci Network: Medicine|
A heart attack is technically called a myocardial infarction. It is damage to the heart muscle due to insufficient coronary artery blood supply. It can range from mild to acute, including causing death.
Your friend, in making the remark about eating too much McDonald's food, is referring to the fact that a diet that includes a lot of saturated fats and trans fats can cause plaque to form in your arteries. This can contribute to the occurrence of a heart attack.
I recommend that you read this Mayo Clinic article on trans fats. http://www.mayoclinic.com/health/trans-fat/CL00032
Everyone should be educated about these fatty acids and realize that we don't have to accept them as part of our diets. We need to make restaurants and food processors know that we won't purchase their products until they make them healthier, which they can readily do.
But, by the way, while I don't eat at McDonald's myself, I'm pretty sure there are some foods there that are healthy, such as salads without dressings. You can take a tiny bottle of extra virgin olive oil with you and use it along with fresh lemon to dress your salads wherever you eat out. Also, you can ask whether the oil they use to cook french fries is trans fat-free and also ask them if they use fresh oil daily.
Stay healthy and enjoy your life.
Try the links in the MadSci Library for more information on Medicine.