Anyone considering a fad diet needs to be reminded that they’re called fad diets for a reason. At best, they’re not useful for long-term weight loss; at worst, they can severely jeopardize your health.

Danelle Olson, RD, LDN, CNSC, a registered dietitian in the Weight Loss Surgery Center at Beth Israel Deaconess Medical Center (BIDMC), explains the problems with fad diets. According to Olson, “There are certain elements, common to fad diets, that people should be wary of. It’s important to remember that any diet that promises quick, dramatic weight loss is potentially harmful to your health and may not be a sustainable solution.”

Olson also recommends avoiding any diet that allows you to eat unlimited quantities of a particular food or macronutrient such as fat or protein. Likewise, any diet that eliminates or severely restricts entire food groups—like, say, carbohydrates—is difficult to sustain and overall can be harmful to our health, she adds. Also, losing weight and maintaining a healthy weight includes building muscle and losing fat, says Olson. "Exercise should be included in any healthy, balanced lifestyle."

Avoiding fad diets comes down to common sense: if it sounds too good to be true, it almost certainly is. Dietitians will tell you that proper weight loss includes a balanced diet and an appropriate amount of exercise. For best results, your doctor or a registered dietitian can recommend a regimen that’s right for you.

“I know it’s not easy, but be patient," says Olson. "When you lose weight slowly and steadily—one or two pounds a week, on average—you’re much more likely to keep the extra pounds off.” If you’re thinking about how to start the New Year off in a health way, Olson suggests following these tips:

1. Practice portion control: A cup of fruit should be no larger than your fist; three ounces of meat, fish, or poultry (a normal serving) is about the size of your palm; and one to two ounces of nuts equals your cupped hand.

2. Eat a variety of colorful foods: Apples, spinach, grapefruit, and black beans not only add color to your plate, they’re good for you, too. Also, eat plenty of lean protein, like skinless chicken or turkey, 90% (or leaner) lean beef, fish, beans, nuts, and eggs; complex carbohydrates such as whole grains, fruits, and vegetables; and "good" fats like those from avocados, nuts, and olives or olive oil.

3. Clean out the kitchen: Start fresh by tossing foods high in calories, fat, and sugar such as cookies, candy, and ice cream. Replace these with lean protein, fruits, vegetables, whole grains, legumes, nuts, seeds, and good fats (nuts, avocados, eggs, and fatty fish as well as peanut, olive, and canola oils).

4. Avoid empty calories: Sugary juices and sodas do nothing to combat hunger. To stay hydrated, drink plenty of water (about 64 oz) throughout the day to avoid consuming unnecessary calories.

If your body mass index (BMI) is 40 or higher, or if you have weight-related health problems, you may want to discuss weight loss surgery with your doctor. For individuals with a BMI between 30-40 who have less weight to lose, an innovative non-surgical procedure called the intragastric balloon might be an option.