Intermittent Fasting For Weight Loss – How It Works And Benefits

by Charushila Biswas
ISSA Certified Specialist in Fitness & Nutrition

Intermittent fasting is a powerful tool for weight loss. Ralston D’Souza, a fitness coach at Ral Fitness says, “Intermittent fasting works by limiting your eating times so that you’re eating fewer calories overall. It really is that simple.” This eating strategy lowers BMI, reduces belly fat, and has many other health benefits.

Read on to know how intermittent fasting works for weight loss, ways to do it, diet chart, calorie intake, and tips. Scroll down!

How Intermittent Fasting Aids Weight Loss? 

Intermittent fasting is an effective way to lose weight fast. Alternate cycles of eating and fasting trick the body functions and calorie intake. Here are 10 proven ways how intermittent fasting aids weight loss:

  • Reduces Calorie Intake

Fasting intermittently helps reduce calorie intake. Reducing about 25% of fasting day energy intake for three weeks has shown to reduce body weight by 3%-8% (1).

  • Boosts Metabolism

Intermittent fasting is extremely good for people with metabolic syndrome and obesity. Alternate day modified fasting and restricted calorie intake helps boost metabolism and mobilizes fat (2).

  • Reduces BMI And Blood Glucose

Fasting intermittently has shown to reduce BMI (Body Mass Index) and blood sugar levels. Research shows that the intermittent fasting diet helps reduce BMI, an indicator of whether a person is in a healthy weight range or overweight or obese (3). Constant high blood sugar or blood glucose levels may lead to type 2 diabetes. Intermittent fasting is an effective dietary strategy to regulate blood sugar levels and reduce the risk of type 2 diabetes (4).

  • Increases Insulin Sensitivity

Impaired insulin sensitivity or insulin resistance prevents the body from metabolizing glucose/sugar. This results in high blood sugar. Studies have shown that calorie restriction and fasting can improve insulin sensitivity (5), (6). This lowers the risk of diabetes and diabetes-related health complications.

  • Uses Fat As Fuel

When you are in a fasted state (not had food for at least 6-8 hours), it becomes easier for your body to burn fat, irrespective of what you have eaten. Instead of drawing fuel from glucose, your body starts converting glycogen and/or protein to glucose. When the protein reserve is fully utilized, fat is used as a source of fuel.

  • Retains Lean Muscle

Retaining lean muscle is important as the muscles are where more number of mitochondria are present. Mitochondria are cell organelles in which sugar is converted to usable energy (ATP). The more the number of mitochondria, the better the metabolic rate. A study showed that intermittent fasting was more effective in retaining lean muscle than daily calorie restriction (7).

  • Detoxifies The Body

Taking a break from eating or fasting helps detoxify the body. Autophagy is a natural process of cellular waste elimination. Improper autophagy leads to toxin build-up, which hampers metabolism. Intermittent fasting gives your body the time to regulate proper autophagy or detoxification. This, in turn, boosts metabolism and reduces the risk of metabolic syndrome (8).

  • Increases Good Gut Bacteria

Intermittent fasting also increases the number and variety of gut microbes, which aid proper digestion (9). It also helps lower inflammation and inflammation-induced weight gain (10).

  • Growth Hormone-Induced Fat Loss

Scientists have found that fasting induces the secretion of growth hormone, which, in turn, aids fat loss (11), (12).

  • Reduces Inflammation

Intermittent fasting reduces inflammation, which helps improve blood lipid profile and reduces blood glucose (13). Chronic inflammation impairs the body’s metabolic function and leads to inflammation-induced obesity (14).

If you are looking for a diet regimen to lose weight, go for intermittent fasting. But first, here are 6 ways you can fast intermittently for weight loss.

Who Can Do Intermittent Fasting?

Intermittent fasting is good and effective for weight loss. But it may not work for everyone. Intermittent fasting may work if:

  • You have a healthy relationship with food.
  • Don’t usually get hungry in the mornings.
  • You have a light/sedentary lifestyle for most of the day.
  • Understand the fundamentals of fat loss and nutrition.

6 Types Of Intermittent Fasting For Weight Loss

  1. 16/8 Intermittent Fasting
  2. 5:2 Intermittent Fasting
  3. Alternate Day Fasting
  4. 24 Hours Fast
  5. Warrior Diet
  6. Skip A Meal

Click here to find out more about these types.

Typically, your body enters the fasting phase if you do not eat for 6 hours. Choose the intermittent fasting type depending on your lifestyle and convenience. But the question is, how many calories should you consume while you are on intermittent fasting? Find out in the section below.

Calorie Intake For Intermittent Fasting

There is no calorie restriction in intermittent fasting. For example, if you choose 16/8 intermittent fasting, you can eat anything and everything in the “feasting” window of 8 hours and then fast for 16 hours.

If you choose 5:2 intermittent fasting, you feast for 5 days and either go on a 24-hour fast for 2 days or follow a very low-calorie diet (500 calorie diet or 800-Calorie Diet) for two non-consecutive days. Find below a sample intermittent fasting schedule.

Sample Intermittent Fasting Schedule 

You don’t have to do intermittent fasting every day! Opt for it when you’re having a night out, or on days when you skip exercise, etc. At the end of the day, it’s all about your strategy. Follow the plan you enjoy the most! Keeping those points in mind, here’s a sample intermittent fasting schedule:

16/8 Fast5:2 FastAlternate Day Fast24 Hour FastWarrior DietSkip A Meal
Breakfast (9:00 a.m.)Monday FeastMonday FeastMonday FeastBreakfast 5:00 – 5:30 a.m.Tuesday and Thursday – Skip breakfast
Snack (10:30 a.m.)Tuesday Fast (Very low-cal diet)Tuesday Fast (Very low-cal diet)24-Hour FastSkip Snack 
Lunch (12:30 p.m.)Wednesday FeastWednesday FeastWednesday FeastSkip LunchMonday And Saturday – Skip Lunch
Snack (3:00 p.m.)Thursday Fast (Very low-cal diet)Thursday Fast (Cery low-cal diet)24-Hour FastSkip Snack 
Dinner (5:00 p.m.)Friday FeastFriday FeastFriday FeastDinner Feast (6:00 – 10:00 p.m.)Wednesday – Skip Dinner
FastSaturday/Sunday FeastSaturday Fast
Sunday Feast
Saturday/Sunday FeastFast 

Here’s a sample diet chart if you choose 16/8 intermittent fasting. Note that you must get a customized diet chart from a registered dietitian. Tweak your diet chart/schedule according to the intermittent fasting type that suits your lifestyle. 

Sample Intermittent Fasting Diet Chart

You can eat anything you want in the 8 hours window. This diet chart is a generic diet chart, and it is not specifically meant for weight loss or any other health issue.

 Day 1Day 2Day 3Day 4Day 5Day 6Day 7
Breakfast (8:30 a.m.)Eggs or oatmealSmoothieAcai bowlEgg and bacon or pancakesMultigrain flakes with milkProtein smoothieWaffles or pancakes
Lunch (12:00 p.m.)Chicken or mushroom saladDahl soup + grilled veggies + 1 piece dark chocolatePasta/sandwichNoodlesGrilled fish and saladShakshukaSmoked fish fillet + herbed rice + 1 cup chocolate ice cream
Snack (3:30 p.m.)Any snack of your choiceAny snack of your choiceAny snack of your choiceAny snack of your choiceAny snack of your choiceAny snack of your choiceAny snack of your choice
Dinner (6:30 p.m.)Mushroom risottoCrab cakes and herbed rice + 1 cup warm milk before bedSoup + 1 piece of dark chocolateChicken tikka masala or mushroom and peas masala and flatbreadTofu and rice noodles + 1 cup vanilla ice creamGrilled chicken, hummus, and pita breadSpaghetti and meatballs + 1 cup warm milk before bed

How much weight can you expect to lose with intermittent fasting? Scroll down to find out. 

How Much Weight Will You Lose?

Research shows that intermittent fasting resulting in 3-8% fat loss in just a week. Intermittent fasting for 6-24 weeks can lead to a weight loss of 4%-14% (1). Your weight loss will also depend on the following factors:

  • Current weight
  • Medical history
  • Workout hours per week
  • Age
  • Diet you follow

The kind of diet you follow while on intermittent fasting or IF also determines your weight loss. Since many people are on the Ketogenic diet, let’s see if you can be on a keto diet while on IF.

Intermittent Fasting While On The Keto Diet

High-fat diets like the keto diet increase satiety, which can help you fast without feeling hungry. The ketogenic diet involves the following macronutrient division: high fat, moderate protein, and low carbs.

First, your body uses glucose and muscle glycogen stores as usable sources of energy. Then, protein is converted to glucose through gluconeogenesis. Finally, your body enters ketosis and produces ketone bodies from the stored fat and uses them as a source of energy. As a result, you drop the pounds fast and effectively.

Exercising While On Intermittent Fasting For Weight Loss

It is recommended to exercise at least 3 hours per week for weight loss and toning. You may also exercise while on intermittent fasting. Alternate days of cardio and strength training is ideal. You may try HIIT, strength training with resistance bands, and bodyweight exercises.

Apart from weight loss, intermittent fasting has a host of health benefits. Most people can follow intermittent fasting as part of a healthy lifestyle. However, it may have undesirable effects in certain cases. Scroll down to the next section to know more.

Possible Side Effects 

  • Intermittent fasting may cause menstrual issues in women and affect their blood sugar levels and fertility (15), (16), (17). Hence, pregnant and breastfeeding women and should consult a dietitian before going for intermittent fasting.
  • People on diabetes medication should exercise caution as intermittent fasting may lead to a drastic drop in blood sugar levels and affect the performance of certain medications.
  • Intermittent fasting may cause irritation and muscle loss and hinder athletic performance if the meals and fast days are not planned properly.
  • Following intermittent fasting for a long time without supervision may lead to eating disorders.

If you are someone who cannot fast and are looking for an alternative diet plan for weight loss, scroll down to check out a list of other ways to lose weight. 

What To Do If You Cannot Fast To Lose Weight?

If you cannot fast to lose weight, do not force yourself. Intermittent fasting might be working for others, but if it is not for you, do not worry. Try the following diets:


  • Drink Bulletproof Coffee–Bulletproof coffee is made with ground coffee, MCT oil, and butter. It tastes great and fills you up for at least four hours.
  • Break Your Fast With The Right Foods– Break your fast with nuts, dates, fruits, and water. You can consume good-quality meat, legumes, veggies, etc. later. You can also let go of inhibitions and feast on junk food, but that’s after you have broken your fast with nuts, dates, and fruits.
  • Be On A Low-Carb Diet – Try to avoid refined carbs like refined sugar, refined flour, junk foods, and fast foods.
  • Consume Less Salt– Salt tends to retain water in the body. Reduce your salt intake by avoiding fast foods, potato chips, packaged sauces, salad dressings, processed meat, and frozen foods.
  • Get Good Rest– Resting and sleeping are as important as being proactive and active. Get 7 hours of sleep, at least 30 minutes to unwind every day, take up a hobby to relax, listen to music, meditate, and build a support system with people who have a positive impact on your life. 


Intermittent fasting is a great way to lose weight and improve your health. Choose a fasting regimen that is convenient for you. Keep yourself hydrated with water, break your fast with the right foods, workout, get good rest, and surround yourself with people who have a positive effect on your life. You will start shedding the pounds and feel healthy, physically and mentally. Don’t procrastinate. Talk to your doctor, and start intermittent fasting to lose weight today! 

Expert’s Answers for Readers Questions

Reasons you are not losing weight on IF.

You may not lose weight on intermittent fasting because you are not adhering to the plan, have an underlying medical issue, are on certain medications that interfere with weight loss (like antidepressants), not working out, not getting enough rest. Keep track of your weight loss by measuring your BMI, body fat percent, and body weight every two weeks.

Is it possible to gain weight while intermittent fasting?

Yes, you can gain weight on intermittent fasting, but it is lean mass that you will gain. Gaining lean muscle mass makes you look slender and toned. Muscles also contain more number of mitochondria that help boost metabolism. You must do strength training or weightlifting if you want to gain lean muscle. Here is a list ofexercises you can do.

Will intermittent fasting work without exercise?

Yes, intermittent fasting will work without exercise. But we recommend including cardio and strength training in your routine for better fitness and health and improved muscle tone.

How long should I do intermittent fasting?

Start with one day a week and proceed to two to three times a week. Depending on your comfort level, you can make intermittent fasting your lifestyle. However, talk to your doctor before deciding to do so.

How long do you have to fast before you start burning fat?

Fasting phase starts after you have not eaten anything for 6 hours. You will start to burn fat once your glucose, glycogen, and protein sources have been used as fuel for energy.

Will I lose weight if I stop eating for 3 days?

You must NOT stop eating for 3 days! Starvation has serious side effects, and going without food for days will make you gain weight instead of losing it.

What is the maximum weight you can lose in a week?

Your weight loss will depend on your current weight, adherence to the plan, workout routine, age, genes, and medications you are on. You can expect to start losing water weight in the first week, which would be about 2-4 lbs.

17 sources

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Charushila Biswas

Charushila Biswas is a Senior Content Writer and an ISSA Certified Specialist in Fitness & Nutrition. She is an alumni of VIT University, Vellore and has worked on transgenic wheat as a part of her Masters dissertation from NRCPB (IARI), New Delhi. After completing her Masters, she developed a passion for nutrition and fitness, which are closely related to human psychology. This prompted her to author a review article in 2015. She has written over 200 articles on Fitness and Nutrition. In her leisure time, Charushila loves to cook and enjoys mobile photography.