What is the 3-Day Diet, how does it work, and is it effective?

Feb 16, 2023
Anna Paula Auziņa
, nutritionist
What you’ll learn

    Are you struggling to lose weight? Thinking of trying the 3-Day Diet plan?

    While the 3-Day Diet plan can be a great way to lose weight fast, it has several drawbacks — all of which could be detrimental to your health — that you should consider before jumping in.

    In this article, we’ll take an in-depth look at the 3-Day Diet plan, its pros and cons, who should avoid this diet at all costs, and much more so that you can decide if this is the right solution for you.

    What is the 3-Day Diet?

    The 3-Day Diet, also known as the 3-Day Military Diet, is a diet that requires adherents to follow a low-calorie eating program for three days. The plan was designed for quick weight loss — claiming to help people lose up to 10 lbs in just three days.

    Since nearly half of the world’s population wanted to lose weight in 2020, it’s easy to understand why many people who want to lose weight fast find this program mighty appealing.

    Percentage of the worldwide population who want to lose weight

    The problem, however, is that this program poses some significant concerns for your health and well-being (which we’ll get into later).

    Despite its name, the 3-Day Diet wasn’t created by the U.S. military, and it also doesn’t follow the principles used in the military. Additionally, while its origins are unclear, it was likely not even created by nutritionists.

    How does it work?

    The Military Diet is a strict, short-term weight loss program that requires drastically reducing your daily calorie intake. The restrictions happen over three days, after which participants take four days “off” from the diet.

    For the first three days, participants need to follow a extremely low-calorie menu (consuming less than 1,000 calories per day). During the following four days, they’re allowed to eat more normally but are still encouraged to keep their calorie intake at 1,500 calories or fewer.

    Some participants do this diet on an occasional basis, while others do three days on and four days off for a month at a time.

    The 3-Day Diet doesn’t have any exercise requirements, but daily walks are encouraged. Thus, rather than calories burned, the diet focuses on significant calorie deficits by cutting out different types of foods.

    Meal plan

    The 3-Day Diet follows a very strict meal plan. Participants are required to eat the exact foods outlined in this plan.

    Image of the 3-day diet meal plan

    There are also vegan and lactose-free alternatives for the 3-Day Diet. For example, participants are allowed to replace meat and fish with tofu, black beans, or vegan sausages.

    Pros of the 3-Day Diet

    The following are some of the main advantages of the 3-Day Diet:

    1. Results in quick weight loss

    One of the biggest benefits of the 3-Day Diet is the potential for weight loss. With more than 41% of U.S. adults aged 20 and over categorized as obese in 2020, the CDC reports that a mere weight loss of 5–10% of their body weight would result in much-improved health.

    Thus, the 3-Day Diet offers participants the chance to lose body weight relatively quickly.

    2. Easy to follow

    The 3-Day Diet plan clearly defines the sets of foods you’re allowed to eat. It outlines exact food combinations with simple measurements and cooking methods. This makes the plan very easy to follow — even for individuals with busy schedules.

    Furthermore, the 3-Day Diet doesn’t contain any overly expensive food items or ingredients, making it a cost-effective diet option.

    3. Includes fruit and vegetables

    The 3-Day Diet includes a wide variety of fruits and vegetables, such as green apples, grapefruit, green beans, carrots, and broccoli. People who tend to slack on their vegetable and fruit intake will be required to eat these items while on this diet.

    Cons of the 3-Day Diet

    Even though the 3-Day Diet does have its pros, the cons regarding your health and well-being far outweigh them. Here are some of the main disadvantages of the 3-Day Diet:

    1. Leads to a low activity level

    The low energy that results from eating around 1,000 calories every day can make it extremely difficult to exercise — especially high-intensity training. Exercising can even be challenging on non-diet days since participants are still encouraged to eat fewer than 1,500 calories daily.

    A lack of physical activity over a long period can lead to severe health risks, such as heart disease, obesity, and diabetes.

    List of the risk factors of low physical activity

    Furthermore, according to a study conducted by ScienceDirect, fitness and physical activity are more effective at reducing health risks than weight loss (especially for obese people).

    Bottom line: To lose weight effectively, you must incorporate both diet and exercise into your daily routine.

    2. Has high levels of added salt, saturated fat, and sugar

    The 3-Day Diet includes processed foods that contain high levels of salt and saturated fat. Between peanut butter, hot dogs, saltine crackers, and cheese, participants need to be careful to avoid exceeding the daily recommended sodium intake of 2,300 milligrams. The diet also calls for a cup of vanilla ice cream, which can be very high in sugar.

    3. Slows down your metabolism

    Losing weight too quickly can slow down your metabolism. And since your metabolism determines how many calories you burn per day, when it slows down, you’ll burn fewer calories.

    Two of the main reasons your metabolism slows down on a very low-calorie diet are:

    • A loss of muscle
    • A fall in hormones that regulate your metabolism, such as the thyroid hormone

    And unfortunately, the drop in your metabolism can last long after you’ve stopped adhering to the 3-Day Diet.

    4. Promotes the wrong kind of weight loss

    While the 3-Day Diet can cause rapid weight loss, it promotes “unhealthy” and unsustainable methods.

    Since this diet is considered a fad diet, it’s easy to gain the weight back (and even add more) once you’ve reached your goal weight and stopped doing the program.

    Common characteristics of fad or crash diets include the absence of physical activity, inconsistent scientific evidence, and maintenance issues.

    List of the common characteristics of a fad diet

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    5. Offers limited nutrient intake

    The 3-Day Diet’s restrictive meal plan puts you in danger of falling short on key nutrients. These include:

    • Calcium: Since very few calcium-rich dairy and non-dairy foods are allowed while on the 3-Day Diet, it’ll be extremely unlikely that you’ll meet your daily calcium requirements.
    • Potassium: Even though potassium-rich foods, like bananas and grapefruits, are part of the 3-Day Diet, you won’t meet your daily recommended intake. This is because the restrictive phase of this diet allows for too few potassium-rich foods.
    • Protein: Adequate protein intake can help with maintaining lean muscle mass, so this strict diet can make doing so difficult.
    • Fiber: Although fiber-packed fruits and vegetables are included in the 3-Day Diet, you may still not be able to get enough fiber. This will ultimately depend on the foods you eat during your four days off.

    These nutrients are essential for good health, detoxification, efficient metabolism, and energy production. A lack of them over a long period can lead to hair loss, extreme fatigue, poor immune function, and weak and brittle bones.

    Who should try (and who should avoid) the 3-Day Diet?

    The 3-Day Diet is intended for people who want to lose a few pounds quickly. Thus, it’s often considered a good short-term diet option for someone looking to shed weight for an “emergency situation,” such as a wedding. For many people, however, this diet plan does not provide enough protein to avoid the depletion of protein stores and reduced lean body mass.

    When adhering to a very low-calorie diet, it is advisable that you keep your protein intake above the minimum recommended dose — ideally between 1.2 and 1.8 g per kg per day (though the amount can vary individually). Since the 3-Day Diet includes minimal protein, you’ll typically be better off finding a more personalized dieting approach when trying to reach your goal weight — even if you’re only planning on dieting for a short time.

    And the 3-Day Diet certainly isn’t recommended as an ongoing or long-term solution. Even though the diet is low-calorie, it isn’t low-sugar, low-salt, or low-cholesterol. This makes it an unhealthy option for most people, especially the following individuals:

    • People with heart disease, diabetes, hypertension, high cholesterol, or other conditions.
    • Teens and children since they need to eat enough calories and ingest enough nutrients for proper growth.
    • People over the age of 50 since the National Institute of Diabetes and Digestive and Kidney Diseases suggests that low-calorie diets can be extremely dangerous for these individuals.
    List of the people who shouldn’t do the 3-day diet

    If you’re in any one of these three groups, it’s best to steer clear of the 3-Day Diet. Consult a health professional instead to find a balanced diet with healthier foods you could try.

    Is the 3-Day Diet effective?

    The 3-Day Diet claims to help you lose up to 10 lbs in three days.

    But is this really possible?

    Well, let’s have a look at the facts. It takes a deficit of around 3,500 calories to lose 1 lb of fat. This means in order to lose 10 lbs of fat, you’ll need a deficit of roughly 35,000 calories. This is something that’s only achievable through extreme calorie deprivation.

    While the 3-Day Diet does cut your calorie intake significantly, it doesn’t cut it by enough for you to lose 10 lbs. Realistically, you can expect to lose around 1.25 lbs (or 0.55 kgs) of actual fat per week while following the 3-Day Diet (if you’re not exercising).

    Let’s break this down:

    Image showing how many pounds a person can lose on the 3-Day Diet

    However, the amount of weight 3-Day Diet adherents lose is highly subjective since it depends on many different factors, including the person’s Basal Metabolic Rate (BMR) — the rate at which your body expends energy to continue necessary functions while at total rest — sex, and exercise routine.

    So why do people claim to be losing around 10 lbs of weight in a week with this diet?

    Most of the weight loss associated with the 3-Day Diet can be attributed to water weight and the loss of muscle mass and muscle tissue.

    Therefore, while 3-Day Diet adherents might believe they’re losing around 10 lbs per week, only around 10% of that is fat loss. And unfortunately, chances are good that they’ll end up putting the weight (and even some extra weight) back on after they stop the diet.

    Difference between long-term and short-term weight loss

    Losing weight is only half the battle. Equally challenging is keeping the weight off for good.

    Short-term weight loss solutions (like the 3-Day Diet) come with their own risks and downfalls, as seen in this article. In addition to putting the weight right back on, you risk other long-term health issues with these solutions.

    On the other hand, if you choose a long-term weight loss strategy instead, not only will you likely find it easier to keep the weight off, but you’ll also experience other health benefits. Some of the main benefits of long-term, healthy weight loss strategies include:

    • Lowered cholesterol
    • Reduced blood pressure
    • Increased mobility
    • Boost in energy level
    • Reduced risk of developing certain cancers
    • Reduced risk of heart disease or stroke
    • Prevention of type 2 diabetes
    • Enhanced sleep quality
    • Improved breathing

    Try this instead of the 3-Day Diet

    While the 3-Day Diet plan could help you shed a few pounds in a couple of weeks, the health risks aren’t worth it.

    Why not try a customized keto diet instead? As a long-term solution, this diet will help you not only lose weight but also keep it off.

    Learn more about how Certified Keto Diet can create a keto diet plan for you based on your needs, preferences, and lifestyle.

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