The 600-Calorie Diet: Can it Streamline Your Weight Loss?

Half the year has already gone and summer is already here, but you still haven’t achieved your New Year’s resolution to shed those extra pesky pounds. Maybe you added a few more kilograms during lockdown and are looking for a quick fix. Could the 600-calorie diet be the answer to your prayers? Can this restrictive eating plan help you fit into those tight jeans or that bikini? Let’s find out!

What Is the 600-Calorie-a-Day Diet?

The 600-calorie diet is a form of intermittent fasting. For those who are unfamiliar with IF, aka intermittent fasting, it’s a diet regimen that cycles between brief periods of fasting, where you don’t eat at all or consume very few calories, and other periods of unrestricted food consumption (5). While this form of dieting has been around for years, it was popularized in the early and mid-2010s by Dr. Michael Mosley, Kate Harrison, and Dr. Jason Fung (10).

The 600 diet is also known as the 5:2 diet in the intermittent fasting community. The rules for the 5:2 diet are quite simple. This eating plan involves eating regularly for five days and eating very little on the other two days of the week (9).

Two very important facts to note about the 5:2 diet are that,

• The fasting days are not consecutive. You don’t eat well from Monday to Friday and then only consume 600 calories on Saturday and Sunday. You’re required to space out your fasting days. For example, fast on Wednesday and Saturday.
• This is not a ‘true fast’. Fasting generally means no food within the allocated days or hours of the fast. However, you’ll still eat on your fasting days on this 600-calorie diet. The only difference will be that you will consume approximately a quarter of your usual calorie intake.
• The 5:2 diet restricts women to 500 calories a day while men can only consume 600 calories.
  

What Does a 600-Calorie Diet Look Like?

This is a form of intermittent fasting that allows you to eat normally (your usual healthy caloric intake) for five days a week while you fast and only consume 600 calories on two other days of the week. While there are no restrictions regarding how much you can eat on the five non-fasting days (27), it’s advisable to mind your portions and caloric intake in order to achieve your weight loss goals faster or in a reasonable amount of time.

Instead of having unhealthy foods such as French fries, pizza, and cheese-filled burgers, you should opt for much healthier options such as:

1. Vegetables – Broccoli, cauliflower, kale, collard green, sweet potatoes, spinach, and squash
2. Any kind of fruits
3. Lean proteins – Chicken breast, ground turkey, eggs, and fish
4. Whole grains – Whole-wheat bread, pasta, and brown rice
5. Healthy fats – Nuts, seeds, olive oil, and avocados
6. High-fiber foods – Beans, legumes, lentils, oatmeal, and sprouted grains

Remember, you should always consult your doctor before you start a new diet or workout regimen.

Sample of a 600-Calorie Diet Plan

If you’re at a loss and wondering what a 600-calorie diet menu looks like, here are some examples of meals and snacks you can enjoy on either of your fasting days:

Option One

Breakfast – Oatmeal

234 g cooked oatmeal

Make sure you cook your oats with just boiling water and don’t add any kind of milk (regular or plant-based).

Calories: 158, Fat: 3.2 g, Carbs: 27 g, Protein: 6 g

Dinner – Smoked paprika paella with cod and peas (18)

1 tbsp rapeseed oil, 1 onion, 2 garlic cloves, 100g brown basmati rice, 1 tsp turmeric, 1 tsp smoked paprika, 500 ml vegetable bouillon, 1 large red pepper, large courgette, 125 g frozen peas, 300 g pack skinless Atlantic cod, 1/3 small pack parsley, 1/2 lemon

Calories: 481, Fat: 10 g, Carbs: 55 g, Protein: 38 g

Total calories for the day: 638

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Option Two

Breakfast – Green smoothie

40 ml coconut milk or coconut cream, 75 ml water, 1 tbsp lime juice, 15 g frozen spinach, 1 tsp fresh grated ginger

Calories: 82, Fat: 8 g, Carbs: 3 g, Protein: 1 g

Dinner – Broccoli and cauliflower gratin with sausage (4)

1⁄6 leek, 1⁄6 yellow onion, 75 g broccoli florets, 40 g cauliflower florets, 75 g sausages, 10 g butter, 1⁄3 tbsp Dijon mustard, 40 ml sour cream, 25 g shredded cheese, 2⁄3 tbsp fresh thyme or dried thyme, salt and pepper.

Calories: 498, Fat: 42 g, Carbs: 12 g, Protein: 18 g

Total calories for the day: 580

Option Three

Breakfast – Garlic bread (14)

For the bread – 40 g almond flour, 12 g ground psyllium husk powder, 1/2 tsp baking powder, 1/4 tsp sea salt, 1/2 tsp cider vinegar or white wine vinegar, 60 ml boiling water, 3/4 egg white.

For the garlic butter – 30 g butter, 1/4 minced garlic clove, 1/2 tbsp finely chopped fresh parsley, 1⁄8 tsp of salt.

Note that the above measurements make approximately five garlic breadsticks. You should only eat one slice of bread.

Calories: 94, Fat: 9 g, Carbs: 1 g, Protein: 2 g

Lunch – Low-carb coconut pancakes (15)

1 1/2 eggs, 1/4 pinch salt, 1/2 tbsp melted coconut oil, 50 ml coconut milk, 15 g coconut flour, 1.1 g baking powder, butter or coconut oil for frying

Calories: 289, Fat: 24 g, Carbs: 3 g, Protein: 12 g

Dinner – Caprese snack

50 g cherry tomatoes, 50 g mozzarella cheese balls, 1/2 tbsp green pesto, salt, and pepper

Calories: 218, Fat: 17 g, Carbs: 3 g, Protein: 14 g

Total calories for the day: 601

Read more: 7-Day Weight Loss Low-Carb Diet: Choose High-Protein, High-Fiber, or Ultra-Low-Carb

Option Four

Breakfast – Low-carb cream cheese with herbs

50 g cream cheese, 1/2 tsp olive oil, 30 ml fresh parsley or basil, 1/4 garlic clove, 1/4 tsp lemon zest, salt, and pepper. 1 celery stalk or other vegetables such as carrots, cucumber, or bell pepper.

Calories: 230, Fat: 22 g, Carbs: 4 g, Protein: 4 g

Dinner – Low-carb cauliflower hash browns

110 g cauliflower, 3/4 egg, 1⁄8 grated yellow onion, 1/4 tsp salt, 1/2 pinch pepper, 30 g butter, for frying.

Calories: 282, Fat: 26 g, Carbs: 5 g, Protein: 7 g

Total calories for the day: 512

Option Five

Breakfast – One three-inch diameter apple

Calories: 95, Fat: 0.3 g, Carbs: 25 g, Protein: 0.5 g

Lunch – Spicy beans and rice (3)

1/4 cup water, 1 tablespoon and 1 teaspoon uncooked brown rice, 425 g canned black beans, 3/8 fresh jalapeno peppers, 1/8 teaspoon ground cumin, 1/2 teaspoon chili powder, black pepper, 1 tablespoon and 1/2 teaspoon shredded cheddar cheese, 3/8 fresh green onions, 56 g black olives

Calories: 96.1, Fat: 9.9 g, Carbs: 11.2 g, Protein: 3.7 g

Dinner – Easy protein noodle low-carb lasagna (6)

1/2 tbsp olive oil, 1/8 chopped yellow onion, 1/2 garlic clove, 75 g fresh Italian sausage, 75 g ground beef, 175 g unsweetened marinara sauce, 110 g ricotta cheese, 1/4 egg, 1⁄8 tsp sea salt, 50 g sliced deli chicken breast, 75 g mozzarella cheese, 30 g Parmesan cheese.

Note that the above measurements are enough for three servings.

Calories: 412, Fat: 30 g, Carbs: 7 g, Protein: 28 g

Total calories for the day: 603.1

This sample meal plan has hopefully answered your question about what you can eat on the 600-calorie diet. Please note that unless otherwise stated, the above recipes are enough for one serving. As the 5:2 diet is quite restrictive on fasting days, remember to keep hydrated by drinking a lot of water. You’re also allowed to have plain, unsweetened coffee or tea.

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What Are the Pros and Cons of the 600-Calorie Diet?

Pros of the 600-Calorie Diet Plan

Intermittent fasting in general is known to have several health benefits, including increased insulin sensitivity, better stress resistance, reduced morbidity, and increased life span (11). Regarding this specific diet, some of its benefits include:

• Reduced Cholesterol

In 2009, a clinical trial on obese individuals – 12 women and four men – involving eight weeks of an alternate-day fast (similar to the 600-calorie diet) showed all volunteers recorded a substantial decrease in the levels of total cholesterol, LDL cholesterol, and triacylglycerol (i.e. triglyceride) concentrations in their bodies (17).

• Weight Loss

When you compare alternate-day caloric restriction to daily caloric restriction, weight loss results are similar. Fewer fat-free mass tends to be lost with alternate-day fasting, which means that muscle mass is better preserved with weight loss on the alternate-day regimen (13). It should be noted that weight loss on the 5:2 diet is even more noticeable when combined with exercise (2).

• Easy To Follow

As this diet only requires you to give up your usual food intake for two non-consecutive days every week as opposed to every single day of every week, it’s more likely that most people will persevere with this way of eating and successfully lose weight (22).

Cons of the 600-Calorie Diet Plan

Thankfully, this diet doesn’t have many disadvantages or reasons to reject it. However, if you’re not used to fasting, some of the side effects you might experience could be a reason for you to choose wisely. (19)

How Much Weight Will I Lose on 600 Calories a  Day?

Consuming only 600 calories a day typically results in significant weight loss due to the severe calorie deficit this creates. The amount of weight lost can vary greatly depending on factors such as starting weight, age, gender, metabolism, and physical activity level. 

If we look at the math, on average, a daily deficit of 3,500 calories is estimated to result in the loss of one pound of body weight per week (19). So, if a person’s maintenance calories (the number of calories needed to maintain their current weight) is around 2,000 per day, consuming 600 calories would create a deficit of approximately 1,400 calories daily. In a week, this could theoretically lead to a weight loss of approximately 2.8 pounds. 

However, this estimate is overly simplistic and doesn’t take the body’s adaptive mechanisms into account. Severe caloric restriction can slow metabolism, decrease muscle mass, and lead to other health issues, potentially reducing the actual weight loss achieved.

Points to Note

This diet shouldn’t be confused with a very low-calorie diet (VLCD). Unlike this intermittent fasting regimen, the VLCD is a clinically supervised diet where a person eats 800 or fewer calories every day (29). A very low-calorie diet is prescribed to obese and severely obese people who are managing diabetes, preparing to have surgery, or preparing for fertility treatments.

While the 5:2 diet requires an intake of 600 calories for two days of the week, a VLCD is done every day for a maximum of 12 weeks and only by patients with a body mass index (BMI) of 30 or higher under the close supervision of a medical doctor (26). Don’t mistake a 600-calorie diet for a very low-calorie diet under any circumstances as such a mistake could be detrimental to your health.

Read more: 24 Weight Loss Smoothies, 2 Diet Plans, and 5 Belly Fat Smoothie Secrets

FAQs

• Can I survive on 600 calories a day?

Surviving on 600 calories a day is incredibly hard and usually not recommended. Such a low-calorie intake is far below the recommended daily allowance for adults, which is typically around 2,000 calories for women and 2,500 for men, depending on activity level and other factors (23). 

Sustaining a diet of 600 calories can lead to severe nutritional deficiencies, as it’s almost impossible to obtain all the necessary vitamins, minerals, and macronutrients on such a restricted diet (20). Prolonged intake of so few calories can result in serious health consequences, including muscle loss, weakened immune function, decreased bone density, and organ failure (21). 

It’s very important to approach weight loss with a balanced and nutritionally adequate diet and seek guidance from healthcare professionals before you make drastic changes to your caloric intake.

• Why am I not losing weight on 600 calories a day?

Not losing weight on a 600-calorie diet can be perplexing, but it’s often due to the body’s adaptive responses to extreme calorie restriction. When the body perceives a significant reduction in calorie intake, it can enter a state of “starvation mode” where the metabolism slows down to conserve energy. This metabolic adaptation reduces the rate at which calories are burned, which makes weight loss more difficult (25). 

Hormonal imbalances, such as increased cortisol levels from stress and decreased thyroid hormone production, can also contribute to the body holding onto weight. It’s important to ensure any weight loss plan is sustainable and balanced and that it provides adequate nutrition to support overall health and metabolic function.

• What will happen if I eat 600 calories a day for a month?

Eating 600 calories a day for a month can have serious health repercussions. Initially, significant weight loss may occur, primarily from loss of water, glycogen stores, and muscle tissue, rather than fat. However, as the body adjusts to the caloric deficit, the rate of weight loss may slow down. Continuous consumption of such a low-calorie diet can lead to severe malnutrition, including deficiencies in essential vitamins, minerals, and macronutrients, which are essential for bodily functions. 

The Bottom Line

The 600-calorie diet is an alternate-day fast that has been proven to help people lose weight. It’s a fantastic way to lose weight gradually and is also a great stepping stone to learn how to live a more healthy lifestyle.

For better results while on the 5:2 diet, make sure you don’t overeat or overindulge on the non-fasting days. Try to keep your foods wholesome and healthy. If you don’t watch what you eat on these five days, chances are you’ll pack on the pounds instead of losing them.

Also, make sure to increase your physical activity during the day by working out. As usual, remember to consult your doctor before you start a new diet or workout routine. You don’t need to put your health at risk just to lose weight.