Fast Food is known to be high on calories. I mean, no matter what you do to the French fries, it would still be fried potatoes at the end of the day. However, if you can't resist fast food, or like to indulge yourself once in a while, follow a few things to make it less harmful.
1. A small size is always better, as it will contain fewer calories.
2. Avoid high-calorie toppings like cheese and mayonnaise. Instead, go for mustard, ketchup, pickles that are low in fat.
3. Always avoid deep-fried. Try out healthier options like broiled, roasted, or grilled. If you are unsure whether the food you like is fried or grilled, just ask. You'd be surprised to know that a grilled or a roasted version is available. And if its not, by asking for it, you may convince the restaurant to include it!
4. Salads -- this is one of the healthiest options you would find. So before digging into that juicy burger, load up on salad. You will find that the craving for the burger has gone away and you end up consuming lesser calories. Of course, remember to go for low-fat dressing.