What Is the Overnight Diet?

What Is the Overnight Diet?

The Overnight Diet is based on the theory that getting a good night's sleep can curb hunger hormones and help you lose weight. It was created by Caroline Apovian, MD, a physician, professor of medicine, and obesity researcher at Boston University, based on her research and experience working with patients who are overweight.

This low-calorie eating plan emphasizes whole foods. It's also very high in protein and restricts processed foods, added sugars, and refined carbohydrates. But the diet also involves a smoothie-only fasting day, which could make it hard for some people to sustain. Also, there is no maintenance phase after the diet—Dr. Apovian says to continue the diet after reaching your goal weight to maintain it.

The 7-Day Diet Plan

With an emphasis on whole foods, the Overnight Diet eliminates refined carbohydrates and processed foods. The eating plan allows unlimited fruits and non-starchy vegetables on "Fuel Up" days, which are also included in "Power Up" smoothie days.

There is a bit of math involved in calculating your daily protein requirement and planning protein-rich meals to meet that requirement. However, there is no calorie counting on this plan. Other than the one-day off, six-days-on method, Dr. Apovian doesn't provide any guidance on the number or timing of meals and snacks.

This is an example of a week on the Overnight Diet. Portion sizes aren't listed for protein since they will vary from person to person, but carbohydrate servings are limited for everyone.

What You Can Eat

Most foods are allowed on the Overnight Diet, but some have limits on servings or serving size.

Fruit and Vegetables

You can eat as many fruits and non-starchy vegetables as you like.

• Spinach
• Mushrooms
• Zucchini
• Asparagus
• Berries
• Apples
• Grapes
• Pineapple
  

Lean Protein

Dr. Apovian advocates eating double the recommended daily allowance of protein and consuming plenty of protein every day (not skipping any days). There is a formula in the book for calculating your daily protein requirement.

• Chicken breast
• Fish and seafood
• Lean cuts of beef and pork
• Eggs

Carbohydrates

While this is a low-carb plan, Dr. Apovian calls the below foods "lean carbs."

• Whole grains
  
• Fruit
• Non-starchy vegetables

Non-Nutritive Sweeteners

• Truvia
• Splenda
• Monk fruit sweetener
• Xylitol
  

What You Cannot Eat

In Dr. Apovian's view, you're not necessarily giving up these foods because she does not consider processed and high-sugar foods "real food."

Refined Carbohydrates

Because carbs are not as satiating as protein, you need to eat more of them to feel full. That, in turn, leads to more calorie consumption, which contributes to weight gain. Therefore, refined carbohydrates are not permitted on this eating plan.

• White bread
• White rice
• Refined pasta
• Refined crackers
  

Processed Foods

• Chips
• Crackers
• Pretzels
• Boxed macaroni and cheese
• Sugary breakfast cereals
• Processed meats
  

Added Sugars

• Candy
• Baked goods
• Sugar

How to Prepare the Overnight Diet & Tips

Some people might find it difficult and time-consuming to plan and prepare whole-food meals (no convenience foods are allowed), consume only smoothies one day a week, and fit in all the sleep and exercise required on the Overnight Diet.

It's important to note that the Overnight Diet is much more than just getting enough sleep. It's about changing what and how you eat. First, you restrict calories by fasting one day each week. On this "Power Up" day, you avoid solid food and only drink smoothies (made with fruits, vegetables, nonfat milk or milk substitutes, and protein from yogurt or protein powder). On the remaining six "Fuel Up" days, you stick to a diet of lean protein, fruits, and vegetables. You don't count calories, measure points, or restrict portion sizes of these foods.

High in protein, the Overnight Diet claims to help people build and retain muscle as they lose fat. Dr. Apovian says that protein is important because it builds muscle mass. Every day you will consume 1.5 grams of protein per kilogram of your so-called ideal body weight. So if your ideal weight is 145 pounds, you will need to consume a minimum of 99 grams of protein each day.

Dr. Apovian's book includes recipes, a meal plan, a guide to eating out, and an exercise plan for a 21-minute workout to be done four times a week. And, of course, the author recommends getting a good night's sleep. Studies have shown that our bodies release a hunger hormone called ghrelin when we don't get enough sleep. When that happens, your body starts to behave as if it needs more food. You get hungry, your stomach starts to grumble, and you may even conserve fat to avoid starvation.

Feeling energized and well-rested may help to curb hunger hormones and promote daily movement to burn more calories. Some studies have shown an association between improved sleep hygiene and weight loss, but more research is still needed to determine the exact role of sleep.

Pros of the Overnight Diet

While this plan is generally not recommended by nutritionists, it does have some healthy components.

• No calorie counting required: You won't have to count calories, carbs, or serving sizes on this plan. The only thing you will need to know is your daily protein requirement and then plan your meals to meet it. This weight loss program may work for some people, but not without some hard work. Losing weight is about more than just getting a good night's sleep, even though the name of this diet may suggest otherwise.
• Cuts out processed foods: Although Dr. Apovian says there's no deprivation on the Overnight Diet, the plan cuts out processed foods, which are a large part of the standard American diet, due to their affordability and convenience.
• May lead to a calorie deficit: Whole foods are typically healthier than processed foods; they offer nutrients and fiber without added sugar, salt, or fat. If you currently eat a standard diet that includes more starchy carbohydrates, fat, and sugar, switching to this strict eating style will probably result in a calorie deficit.
• May lead to weight loss: If you follow this plan perfectly, you're likely to cut enough calories to lose a few pounds per week.
• Promotes healthy lifestyle habits: Despite its restrictive eating plan, "The Overnight Diet" book does include recommendations for sleep and exercise. However, there is little advice in the book on improving sleep quality and duration, and the suggested exercise routine might not work for everyone. Regardless, getting enough sleep and exercise is important. For the purposes of weight loss, studies suggest getting more than 7 hours per night of sleep. And research continues to show an association between improved sleep and an increased willingness to exercise, which can lead to weight loss.

Cons of the Overnight Diet

Despite its advantages (and its medical pedigree), the Overnight Diet has a few notable drawbacks.

• May be difficult to follow: The diet limits carbohydrates and calls for no solid foods at all for one day per week. Not everyone may find this eating plan feasible due to factors like budget and time constraints.
  
• Weight loss is likely to be temporary: Dr. Apovian is careful to say that the Power Up days can promote a loss of up to two pounds, for up to nine total pounds lost per week. In reality, however, this is not a realistic amount of weight to lose for most people in the short term. Additionally, the restrictive eating plan may be difficult for some people to stick to for the long term.
• Unhealthy rate of weight loss likely: While there are no common risks associated with the Overnight Diet, it overpromises rapid weight loss results of nine pounds in a week. Experts generally agree that a reasonable rate of weight loss is 1 to 2 pounds per week. Research shows that weight loss resulting from restrictive dieting is not always sustainable and can lead to weight regain.
• Not well-balanced: The Overnight Diet restricts healthy food groups on smoothie-only days, which is not advisable for the long term and could lead to nutrient deficiencies. A more sustainable approach would include a variety of nutrient-dense foods in your diet each day.

Is the Overnight Diet a Healthy Choice for You?

The USDA 2020–2025 Dietary Guidelines for Americans recommends consuming a variety of nutrient-dense foods such as fruits and vegetables, legumes, whole grains, lean protein, low-fat dairy products, and healthy fats. The USDA also recommends limiting foods and beverages with higher amounts of added sugars, saturated fat, and sodium, and also limiting the consumption of alcoholic beverages.

The Overnight Diet advises eating about double the amount of protein suggested in federal dietary guidelines. That crowds out some other foods, notably carbohydrates, which are still recommended by the USDA as part of a healthy, balanced diet. The USDA doesn't advocate "smoothie days" either.

Dr. Apovian says calorie counting isn't necessary. But for many people, determining a calorie target (one that creates a calorie deficit) and adhering to it is a good weight-loss strategy. For weight maintenance, the USDA recommends a daily calorie intake of about 1,600 to 2,400 calories per day for women and 2,000 to 3,000 calories per day for men, but that number varies greatly depending on weight, age, sex, and activity level.

To lose weight, you will need to reduce calories below what you are consuming through diet. Use this tool to calculate your daily calorie needs to meet your weight loss goal.

A Word From Verywell

Getting a good night's sleep, exercising regularly, and eating a nutritious diet with plenty of lean protein, fruits, and vegetables is a smart weight-loss plan. But you don't necessarily have to buy a book and subscribe to a restrictive eating program to make those changes in your life. Keep in mind that while Dr. Apovian is a knowledgeable physician, she's not your physician. So her advice isn't customized to your specific needs. If you're looking to lose weight, talk to your own doctor about the best ways to do so.

Remember, following a long-term or short-term diet may not be necessary for you, and many diets out there don’t work, especially long-term. While we do not endorse fad diet trends or unsustainable weight loss methods, we present the facts so you can make an informed decision that works best for your nutritional needs, genetic blueprint, budget, and goals.

If your goal is weight loss, remember that losing weight isn’t necessarily the same as being your healthiest self, and there are many other ways to pursue health. Exercise, sleep, and other lifestyle factors also play a major role in your overall health. The best diet is always the one that is balanced and fits your lifestyle.