How Effective Is Intermittent Fasting For Weight Loss?

By Lily •  Updated: 06/16/21 •  10 min read

I’m guessing you already heard all the raves about intermittent fasting. When it comes to losing weight, we are willing to try everything and anything.

I usually ignore all the fad diets that come out as I have already found the secret to losing weight.

But intermittent fasting is not a diet. And it is definitely something I practice every day since I discovered it.

This post will explore how intermittent fasting for weight loss can be effective, including pros and cons.

how effective is intermittent fasting for weight loss

What is Intermittent fasting?

Intermittent fasting is more than sometimes skipping meals. It means restricting calorie intake and following a precise schedule of when you eat, but not worrying so much about what you eat. 

Intermittent fasting aims to keep your body burning fat as energy instead of glucose/sugar.

Our body relies on glycogen stores for energy and function the first 10-12 hours of going without food. 

After 12 hours without food, our body works harder and starts burning off fat. Think of this as peak fat burning, which you won’t get if you eat before the 12-hour mark.

Fat burning peaks between 12-14 hours of fasting, and it is best to start eating again after this time. 

Diet experts suggest starting gradually and adjusting your schedule until you reach 14 hours.

intermittent fasting weight loss 1

Does Intermittent Fasting Work For Weight Loss?

I don’t intermittently fast to lose weight. I do it because studies have linked intermittent fasting with a longer lifespan (more on this later). 

However, I do believe that it helped me on my weight loss journey. Let me explain… 

Sometimes I would get the munchies at night. But because my fasting period had started, I would stop myself from eating anything. It’s a mental game I played with myself.

I have avoided eating so many late-night snacks and therefore reduced my daily calorie intake this way.

On average, intermittent fasting will help you lose around 0.55 pounds/0.25 kg per week. You can also lose inches (about 4-7% of fat around the waist). 

Why Am I Not Losing Weight On Intermittent Fasting?

Keep in mind that intermittent fasting does not give you the right to stuff your face when the fasting period is over. 

If you eat more calories in a day than you’re supposed to, you won’t lose any weight and might even gain weight! So remember that you need to be in a caloric deficit every day if you want to lose weight.

To learn more about what it means to be in a calorie deficit, check out my blog post titled “How Many Calories Should You Eat To Lose Weight.”

Which Intermittent Fasting Is Best For Weight Loss?

There is no one-fits-all type of intermittent fasting. We all have different bodies and different schedules. 

Consider the following meal planning methods, try them out, and then decide which one you want to stick with.

1. 12-hour Fasting

This path is recommended for beginners. Choose a 12-hour period where you can restrict yourself from eating. Include sleeping time in your 12-hour fasting window. For example, eat from 6 a.m. to 6 p.m., then fast from 6 p.m. to 6 a.m.  

Advantage: More time to eat. 

Disadvantage: This may not provide significant results.

2. 16/8 Fasting

Increasing fasting time from 12 to 16 hours is recommended if you don’t get results from 12-hour fasting. If you’re new at fasting, start with 14 hours. A great way to do this is by eating your last meal at 8 p.m. Skip breakfast the next day and have your first meal at lunchtime. 

Advantage: Gets results faster and promotes weight loss. 

Disadvantage: Longer fasting hours may leave you feeling hungry if new to fasting.

3. 5:2 Fasting

Five days of regular diet and two days of fasting each week means you won’t have to skip many meals. Instead, choose two separate days to reduce daily calorie intake to 500 calories for women/600 calories for men. Fewer calories will reduce meals on both fasting days to two small food breaks. 

Advantage: Three meals a day on most days. 

Disadvantage: Caloric reduction may not be enough if you want to lose more weight.

4. Weekly 24-hour Fast

Fasting for 24 hours once or twice a week is challenging, but many find it effective. Days should be set as far from each other as possible. Start by fasting from dinner to the following day’s dinner, breakfast to breakfast, or lunch to lunch. 

Advantage: Eat normal for five days and still lose weight. 

Disadvantage: A 24-hour fast may make you feel tired and irritable, and trigger headaches, especially when starting.

5.  Alternate Day Fasting

Fasting every other day can be done by full fasting with zero food, or restricting calories to 500 per day for women/600 for men. 

Advantage: Significant weight loss over 12 weeks and better heart health. 

Disadvantage: It may be challenging to maintain since there are more days each week of food deprivation.

6. The Warrior Diet

This approach includes fasting in the morning, then eating a big meal at night, or vice versa. The only allowable eating time per day is four hours. For the remaining 20 hours, you can only snack on small pieces of fruits and vegetables. 

Advantage: No need to avoid food altogether. 

Disadvantage: Food quality might be compromised during “feasting.”

7. Spontaneous Meal Skipping

The most flexible method allows you to skip meals when convenient, such as when you’re busy and lack time to cook or eat. 

Advantage: It feels more natural. 

Disadvantage: Some people may eat more if hunger tolerance is lower. Monitoring is a must for this method to be successful.

What To Eat Or Drink While Intermittent Fasting?

During your eating window: intermittent fasting is not a diet, so you can eat or drink anything you want.

However, if you are trying to lose weight, I would not recommend that you completely ignore everything you are putting into your body. 

My advice is that you follow a healthy plant-based diet. For more information, check out my blog post “How To Lose Weight On A Plant-Based Diet: The Ultimate 7 Step Guide!”

For optimal results, choose filling foods and plan your meals. Then, you won’t feel like you’re starving during your fasting time selected with the right food choices.

Experiment with these fulfilling plant-based foods:

During your fasting window: you can drink fluids, but you are very limited. The safest is water. If that gets boring, try zero- or low-calorie drinks, including:

Though there are complex formulas for optimal hydration during fasting, many experts simply say, ‘follow your thirst.’

Is Intermittent Fasting Only for Weight Loss?

We’ve discussed how intermittent fasting can aid weight loss. Still, it is believed to be connected to other health benefits, including:

Most of the above benefits are based on limited studies and shouldn’t be thought of as confirmed health benefits. However, current studies on intermittent fasting are also leaning towards these connections.

The anti-aging claim, for instance, is based on possible connections between fasting and reducing calorie intake, which can lead to a longer life. When you give your body time to heal, rest, and don’t need to spend much time digesting, it potentially elongates your lifespan.

For more information on this subject, read Jillian Michaels’ book “The 6 Keys: Unlock Your Genetic Potential for Ageless Strength, Health, and Beauty.”

What Are The Negative Side Effects Of Intermittent Fasting?

If you are generally healthy, intermittent fasting should be safe. But there are also mental and physical danger signs to consider, including:

Women should take a slightly different approach than men since poorly planned fasting can be harmful. I personally do not fast more than 13-14 hours at a time. 

Female bodies are especially sensitive to calorie restrictions, so women may experience missed periods, metabolic disturbances, or more significant risks of poor bone health. 

Doctors strongly advise against intermittent fasting if you have any of these conditions:

Be sure to consult your doctor before starting an intermittent fasting program. Especially if you have health conditions that could be aggravated. 

And if you notice any unusual health changes during fasting, stop and contact your doctor.


1. Is intermittent fasting necessary to lose weight?

No, you don’t need to practice intermittent fasting to lose weight. Weight loss is calories in and calories out, and not about what time of the day you eat. 

2. Is intermittent fasting effective without exercise?

Yes, you don’t need to exercise to lose weight. However, you won’t be able to continue eating as much as you are now. So choose!

3. How long does weight loss take with intermittent fasting? 

If you are not counting your calories, it will be challenging to determine how long it will take for you to lose significant weight.

In addition, everyone has a different metabolism, and your body might react differently to someone else’s who is also practicing intermittent fasting.

However, a healthy weight loss goal is about 1-2 pounds per week. Be patient.

4. How to break my weight loss plateau on intermittent fasting?

To continue losing weight, you need to be in a calorie deficit by the end of the day. So either eat less or exercise more!

5. Should I continue intermittent fasting if I’ve reached my weight loss goals?

You don’t have to, but I suggest that you make intermittent fasting a habit, even if you only do it for 12 hours a day. The studies linking fasting to a longer life are undeniable! 

6. Is it OK to do intermittent fasting during menopause?

I found no studies showing that practicing intermittent fasting during menopause can harm women. 

On the contrary, a 2012 randomized controlled trial concluded that intermittent fasting can help postmenopausal women significantly decrease their body weight. 

7. What is the best app for intermittent fasting? 

I love the app called “Zero.” It has a free tier and a premium one, but the free version is all you need.

You choose your fasting goal (13 hrs, 16 hours, etc.), and it tracks how many hours you have been fasting for. It is very easy and straightforward to use.


Intermittent fasting is an increasingly popular weight loss technique. The goal is to eat all your calories within a specific time window, and then go without food the rest of the day.

While intermittent fasting for weight loss can be effective, it is not necessary. 

Weight loss can also come from exercise, eating a low-calorie diet, and reducing oils and sugars. But if you need a boost, give intermittent fasting a try! 

Start gradually and ease into it. Choose nutritious foods, prepare, and discipline yourself! 


Hi, I'm Lily! Like you, I have struggled with my weight. It was not an easy journey but I was able to lose 40 pounds and have kept it off for 14 years. My goal is to share with you all the research, tips, and tricks that I have learned over the years to help you lose weight also.