Is a trip to the burger bar possible when dieting? No it isn't impossible but it is difficult to eat healthily at most burger bars. French fries are high in fat and burgers, though a good source of protein are often high in fat and calories (especially if cheese is added to the burger).
Add to this a large milk shake and apple pie and you have consumed over your total daily calorie and fat intake.
Calorie wise as a guide a typical quarter pounder with medium fries would be 800 calories. Although a plain burger in a bun would be around 250 calories and 10g of fat.