Best Crash Diet For Fast Weight Loss, Diet Plan, Side Effects

Learn the benefits and risks of getting on a crash diet and know how to do it safely.

Medically Reviewed by Merlin Annie Raj, RD (Registered Dietitian)
By Charushila Biswas, MSc (Biotechnology), ISSA Certified Fitness Nutritionist

A crash diet is the fastest way to lose weight. It restricts calorie intake and is good for short-term weight loss. But being on a very low-calorie diet for a long period may lead to eating disorders, compromised immunity, hair loss, and irregular menstruation (1), (2).

However, there’s a way to crash diet safely for an upcoming event. Check out the 7-day crash diet plan, safety, and risks. Read on!

What Is A Crash Diet?

A crash diet is a quick weight loss dieting method for shedding pounds in less time. It is a restrictive or a very low-calorie diet (<= 800 calories) plan for short-term weight loss goals.

A crash diet is not meant for long-term weight loss. The results of a crash diet are short-lived, and you will gain the pounds right back if you do not eat healthy and workout. However, for an occasion right around the corner, you may try a crash diet. Here’s a list of popular types of crash diet. 

Types Of Crash Diet

Some crash diets allow you to only eat soup or salads, or drink liquids.


1. Master Cleanse

The Master Cleanse may help you lose 10 pounds in a week. It includes vitamin C-rich lemon juice, two to three teaspoons of maple syrup, and a pinch of cayenne pepper.

Cons – All you can drink is lemonade. You may feel extremely hungry and experience nausea, irritability, and mood swings.

2. Juice Cleanse Diet

Juicing is a great way to be on a liquid diet without compromising on nutrients. You will consume dietary fiber-rich and vitamin C-loaded fruit juices that will flush out toxins and rejuvenate your body. It is also good for the skin.

Cons – It may not be sustainable for more than two days.

3. Cabbage Soup Diet

The cabbage soup diet is a nutritious soup diet made mainly with cabbage and other veggies. All you have to do is consume this soup to lose water weight quickly and slim down.

Cons – Consuming only this soup for more than a day might cause boredom.

4. Grapefruit Diet

The grapefruit diet involves consuming half a grapefruit and other healthy foods in every meal. It aids quick weight loss without compromising on health.

Cons – Consuming grapefruit for every meal may cause nutritional deficiency and tooth enamel erosion, and it can be super challenging to eat only one type of fruit.

5. Hollywood Diet

The Hollywood diet has been popularized by Hollywood celebs and claims to cause a weight loss of 10 kg in just 48 hours. All you have to do is drink an herbal mix called “Hollywood diet,” which is available in supermarkets and online. 

Cons – It is not doctor-approved. Your body may react to the herbs in the mix, and just drinking this mix will make you irritable and compromise on immunity.

[Read: Is The Daniel Fast Diet Healthy]

6. Chicken Soup Diet

This diet requires you to consume chicken soup for seven days. You may add veggies of your choice to enrich the soup with vitamins and minerals. You may also have freshly pressed fruit juice as a snack.

Cons – It is not for vegans and vegetarians.

Clearly, crash diets are not nutritionally wholesome, but they aid quick weight loss in a short period. If you want to try it, do it for three days or seven days. Find an easy 7-day crash diet plan below.

7-Day Crash Diet Plan For Quick Weight Loss

How much weight will you lose after being on a crash diet for three to seven days? Find out below.

How Much Weight Will You Lose?

Happy woman checking her weight after crash dieting


You may lose up to 10 pounds (4.5 kg) in seven days. You will lose water weight in the first three days, and your body will shift to the fat-burning mode . in the next four days.

Crash diets are only meant for short-term weight loss. Does that mean that they are not safe? Find out in the next section.

Is Crash Diet Safe?

Crash diets are safe if done for one to two days. Sometimes, doctors recommend crash diets to people who need to lose weight quickly for surgery. But being on a very low-calorie diet for a prolonged period, without the supervision of a licensed professional, might make you land in hot water. How can you crash diet safely? Scroll down to find out.

[Read – What Is The SlimFast Diet]

How To Crash Diet Safely

Woman eating a healthy meal


Here’s how to crash diet safely:

  1. Choose A Crash Diet That’s “Doable”– Crash diets are emotionally taxing, but when you have so many options, choose one that is convenient for you. If only eating an apple a day is not your thing (must be supervised by a doctor), go for a soup diet that will keep you full and nourished. 
  1. Cut Back On Refined Sugar– Avoid consuming refined sugar or foods containing it, like cake, pastry, doughnuts, ketchup, dips, candies, and chocolates.
  1. Snack Smart – Going on a crash diet can be easy if you know how to snack smart. Consume low-calorie, nutrient-rich foods like fruits, baby carrots, cucumber, unsalted nuts (limited quantity), half a cup of plain yogurt, home-baked veggie chips with yogurt dip, and green tea. 
  1. Do It For A Limited Time– Every crash diet has a time duration, say, two days or seven days. Stick to the specified duration, and you will not overwhelm your body with low-calorie diets. If losing weight is not urgent, you can follow the 1200 or 1500-calorie diet. 
  1. If Possible, Avoid Social Gatherings– You know what happens when you go to parties and gatherings – diet goes out the window! Hence, it is best to avoid parties. If you need to offer support to a friend or a family member (and you happen to live in the same city), carry your food or choose foods that will not throw you off your diet.
  1. Avoid Alcohol– Alcohol gets converted to sugar, which gets stored as fat. Also, drinking alcohol while on a crash diet may cause glucose imbalance in your body. 
  1. Refrain From Vigorous Exercise– If you are on the Master Cleanse or Juice Diet, it is best to avoid exercising. You may do light stretching and yoga but not full-fledged cardio and strength training. 
  1. Drink Water With Rehydration Salts – Crash dieting might require you to drink water or fruit juice frequently. Drink water with rehydration salts at least twice a day to keep your electrolytes balanced. 

Note: Talk to your doctor before you start the crash diet.

If you crash diet safely, you can reap the following benefits.

Benefits Of Crash Dieting

  • Causes quick weight loss
  • Gives instant satisfaction
  • May be good before certain surgeries (has to be approved by your doctor)
  • Less costly

You must keep a few points in mind before you start crash dieting.

Things To Do Before Going On A Crash Diet

  • Count the number of days you have before the special event. If it is a month away, try the Mediterranean diet and do some cardio to lose weight.
  • Talk to a dietitian or your doctor, especially if you are a new mother, have undergone surgery, have a BMI over 30, are on antidepressants or any other medication that hinders weight loss, or are over 50 years.
  • Stock your kitchen with foods you are going to consume in the coming week. Toss out all other “distraction foods.”
  • Keep a journal. You will undergo mood swings. Writing a journal can help during those times.

But things can go quite wrong when you misuse the crash diet. Here are the side effects: 

What Happens When You Misuse The Crash Diet?

Woman looking sick and tired because of crash dieting.


Crash Diet Side Effects

It is really easy to get carried away and misuse crash diets. In that case, the following may happen:

  • Eating disorders
  • Slowed metabolism
  • Anxiety
  • Depression
  • Muscle loss
  • Slowed cell and organ function
  • Compromised immunity
  • Impaired brain function
  • Weak bones
  • Poor attention
  • Hair loss
  • Skin problems

Crash dieting for a prolonged period is unhealthy and should not be done without professional guidance. This brings us to the next topic – should teenagers crash diet? Since the crash diet gives quick results, many teenagers want to follow it. But should they? Find out below.

Should Teenagers Crash Diet?

No, teenagers should not crash diet. The ages of 13 to 19 are part of the growing phase. Going on crash diets might stunt your growth and affect your mental health. If you do need to lose weight, seek the help of a professional.

Talk to a registered dietitian and get a customized diet chart. You must also be physically active and aim to be fit and strong. Also, remember, you don’t have to fit into any size to feel beautiful and worthy. Be healthy and happy, and pursue your dreams.

 Here’s the takeaway message.

Crash Diet Is Not For Long-Term Weight Loss

Crash diets are unsustainable and unhealthy. The weight that you lose is mostly water weight. Moreover, most people tend to misuse these diets, which causes health issues. We do not recommend going on an unsupervised crash diet. You must consult your doctor before trying out our sample 7-day crash diet plan.

Crash diets are the quickest way to lose some pounds quickly, but they can turn out to be extremely dangerous if misused. They have to be treated as short-term weight loss options. Following these diets, which involve taking less than 800 calories a day, for more than a week is not advisable. Your body may get deficient on the nutrient front and lead to adverse effects like weak immunity, nausea, muscle loss, etc. Consult a doctor if you are a new mother, obese, old, or on antidepressants. These diets are a strict no-no for teenagers as they may impact their physical and mental growth. If you have a larger time window (like a month) for a special occasion, opting for the Mediterranean diet is advisable.

Frequently Asked Questions

Is it possible to lose 10 pounds in 3 days crash diet?

No, you will not be able to lose 10 pounds in 3 days. That’s a bit too ambitious and dangerous. In 3 days, you will lose the water weight, which can go up to 2-3 pounds.

How can I lose 20 pounds in a week?

Losing 20 pounds in a week is not possible unless you go for weight loss surgery. In a week, you can lose 1-2 pounds if you follow a low-calorie diet and workout. If you follow a 7-day crash diet, you may lose up to 10 pounds in a week.

What should I stop eating to lose weight?

Stop eating sugary foods (soda, sugar-free foods, candy, cake, pastry, doughnut, cookies, macaroon, and sweets), foods loaded with trans fats (like cookies, biscuits, chips, fries, fried chicken, and frozen pizza), high sodium foods (like soda, fries, bottled sauces, ketchup, ready-to-eat foods, frozen foods, and pickles), refined flour, white rice, and alcohol.

How can I lose belly fat fast?

To lose belly fat fast, you must go cut at least 500 calories from your current diet. For example, if you consume 2000 calories per day, start consuming 1500 calories. You must also start doing cardio and ab exercises every alternate day.

Is Keto a crash diet?

No, keto is not a crash diet. It is a high-fat, moderate protein, and low-carb diet. Crash diets are typically very low-calorie diets. Keto diet is a high-calorie diet.

Is SlimFast a crash diet?

No, SlimFast diet is not a crash diet. You consume 6 meals per day in this diet and lose up to 1-2 pounds in a week.

What can I do to recover after a crash diet?

Increase your calorie intake gradually, but keep a check. Do not start eating high carb foods, more sugar, and fat just after the crash diet. Continue eating veggies, fruits, and proteins in bigger portions now, and drink a lot of water.

What’s wrong with crash dieting (or controlled anorexia)?

Anorexia is an eating disorder. A crash diet will not go wrong until you do not follow the dietitian’s or doctor’s instructions. Many of us crash diet by starving ourselves to lose more weight in a short span of time. That’s not the way to go about it. Consume small portions of all kinds of healthy food.

How does a crash diet affect health and metabolism?

Crash dieting for a prolonged period will affect your body’s normal activities. As it is a low-calorie diet, your body will be deprived of the nutrition that is required for it to function properly. You will start feeling weak and end up weakening your body’s immune system. As you starve for longer hours, the body starts accumulating whatever food it gets. This reduces the metabolic rate and leads to a host of eating disorders. Also, this can lead to weight gain instead of weight loss.


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Charushila is an ISSA certified Fitness Nutritionist and a Physical Exercise Therapist. Over a span of 5 years, she has... more

Merlin Annie Raj

(Registered Dietitian Nutritionist)
Merlin Annie Raj is a Registered Dietitian based out of Hyderabad, India. She has vast experience in Clinical Nutrition as... more