The veggie burger is manufactured -- who knows what is in it and then fried or broiled? Plus a white, denatured bun. The french fries are fried in some type of oil which is probably rancid -- plus all of their regular salt on them. The diet Coke has aspartame in it which can affect your memory or mood. Have a regular Coke; at least, you are aware then that the sugar is not good for you. Manufactured lite foods, etc. are not natural and so your body gains nothing from them but toxins and more work to try to keep you alive.
All of these foods build up toxins in your body. If you want to be healthy, you must know whether the food will assist you in building your body or be harmful to you by increasing your load of toxins.
Due to the nature of the business, most fast-food (and other) restaurants use frozen or portion-packed foods -- these all have preservatives in them, adding to your toxic load.
Your own kitchen is the safest one; you control everything that goes through it. Learn about natural foods, eaten in their natural state, plain and simple; your body will thank you for it.
If you eat healthfully most of the time, you can handle an occasional meal at McDonald's, but don't imagine that you are contributing to your health.