It seems simple enough: to cut calories, sip a shake or eat a bar instead of a meal. There’s no risk of accidentally eating too much, and you don’t have to spend time preparing a meal or measuring portions.

Also known as meal replacement diets, these programs have their pros and cons. A study published in The Journal of the Academy of Nutrition and Dietetics showed they can help people effectively lose weight. But, no single diet works for everyone. Before you try meal replacement, here’s what you should know:

•  Talk with your doctor before you start any diet plan.

•  Eat plenty of whole foods daily. Fruits, vegetables, whole grains, lean protein, low-fat dairy and healthy fats are recommended by the USDA. Bars and shakes cannot fully replace the nutrients you get from whole foods.

•  Get the right amount of calories. There’s a healthy range of calories based on your age, weight and activity level. Learn yours by going to the USDA’s SuperTracker Tool at supertracker.usda.gov.

•  Drink plenty of water between meals to stay hydrated. This can improve your energy levels and may help you fight off hunger.

If you follow the guidelines, you may find success with a meal replacement plan. Be sure to follow the plan as recommended and still eat nutritious foods at other meals. If you find you’re too hungry or it’s not working for you, talk with your doctor or a dietitian about another option.