If you've followed a fad diet, you have plenty of company. But have you been able to stay on these deprivation diets for a long time? And if you did lose weight, did the pounds stay off once you went back to your usual way of eating? Fad diets don't help you keep off the weight in the long term. So what does work? The best diet is not a diet at all, but a way of life that includes food you enjoy, exercise, and healthy habits. Here's some simple, straightforward advice. Variety is Key Just as a car needs the proper gasoline to make it run, a body needs a healthy diet to develop properly. That means the right balance of protein, carbohydrates, and fat -- as well as a host of other nutrients. When you go on a fad diet and exclude necessary nutrients, you're putting yourself at risk for becoming ill. Getting too little of any nutrient may not cause an immediate problem. But if it's lacking for a long time, you may find you have health problems. Practice Portion Control Food servings have grown larger and larger over the years. And fast-food restaurants aren't the only places you'll find supersized meals. Researchers have noted that from 1970 through the 1990s, portion sizes of hamburgers, burritos, tacos, french fries, sodas, ice cream, pie, cookies, and salty snacks increased -- whether the foods were eaten at home or at restaurants. What does a healthy serving size look like? A cup of fruit should be no larger than your fist. An ounce of meat or cheese is about the same as the size of your thumb from base to tip. 3 ounces of meat, fish, or poultry (a normal serving) is about the size of your palm. 1 to 2 ounces of nuts equals your cupped hand.