How long does it take to see results with intermittent fasting?

How long does it take to see results with intermittent fasting?
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Ah, intermittent fasting. In my opinion, it’s one of the most effective and easiest ways to get lean. I’ve been on intermittent fasting (IF) sporadically for nearly a decade now and every time I go on this diet, I always see results. 

So, how long does it take to see results with intermittent fasting, you ask? 

That depends on a lot of things, actually. But if we’re talking about even the smallest decrease in the number you see on the weighing scale, IF can work its magic in as little as a week. Generally though, you and other people will start noticing weight loss after 8-10 weeks in the diet.

But like any other diet, there’s more detail to intermittent fasting that I believe you should know about if you want to maximize your weight loss potential. These include how exactly the diet works, hurdles that may prevent you from losing weight, and many more. 

Let’s talk about them, shall we? Starting with a question that you may well be wondering:

Is intermittent fasting effective for weight loss? 

Absolutely. 

Regardless if you’re overweight/obese and you want to get into a healthier weight, or if you already have a normal weight right now but want to look leaner still, there’s plenty of scientific and anecdotal evidence that proves how intermittent fasting is one of the most effective weight loss trends. 

As a matter of fact, a journal from Nutrients reviewed several studies on different methods of intermittent fasting and found that all of them were effective treatments to obesity. 

If you’re looking for real-life weight loss success stories, a simple Google search will point you to hundreds of thousands of body transformations.

So, how does intermittent fasting work anyway? 

Any weight transformation relies on the fundamental principle of energy balance — and this, of course, includes intermittent fasting. Energy, in this case, means calories. 

Per research, any change in body weight is the result of an imbalance of energy content between calories consumed and calories expended. Specifically for weight loss, you want to be burning more calories than you eat. 

Now, IF theoretically helps make this happen because fasting helps stop you from overeating. In turn, you consume less calories than you burn, leading to weight loss. 

More specifically though, research shows how there’s a complex interplay between several hunger-related hormones (i.e. insulin, ghrelin, and leptin) with the end result of helping you feel less hungry. 

The same research also suggests how the interaction between these hormones is largely what’s responsible for the health benefits of intermittent fasting, but they can only happen if you consumed less calories overall. 

This brings us to a problem that some of you might be having. 

Why am I not losing weight on intermittent fasting?

Well, there are a few possible reasons.

1. Maybe you’re still eating too much

Ultimately, any problem with weight loss goes back to the principle of energy balance. 

As I’ve already explained, the science behind how intermittent fasting works is that it supposedly makes it easier for you to eat less food.

Now, if you still ate the same amount of calories as you did and you’re not burning more calories throughout the day, you’d still be stuck with the same weight because you’re not in a state of caloric deficiency (or negative energy balance). 

The fix? Consider counting your calories. 

It’s probably not very doable long-term because, let’s face it: while keeping track of whatever you eat and drink isn’t too big a deal, it’s still more work than not doing it at all. 

However, I do believe counting calories helps you get a handle on how much food you have to consume to lose weight. Once you’ve got that down, feel free to stop calorie-counting and just stick to good ol’ portion control. 

Under Armour’s MyFitnessPal is what I’ve been using sporadically whenever I go on a diet, so you might want to try it out, too. This isn’t a plug or anything. It’s free (though there’s a paid version), has a built-in calorie tracker, and a food diary to make counting calories so much easier than it already is.

2. You’re eating too little

Counterintuitive to what I just said, eating too little might actually hurt your weight loss aspirations. 

Per the MayoClinic, you only need to eat around 500-1000 fewer calories to lose 1-2 lbs of weight per week — which is, by the way, the safe weight loss rate you should aim for. 

Now, if you deducted more calories than that, you’d certainly lose more than 1-2 lbs for the first couple of weeks but eventually, your body adjusts and goes into “starvation mode” where your metabolism slows down and burns less calories. 

The fix? Consume just the right amount of calories without compromising your metabolism too much. Losing just 1-2 lbs per week is typically a telltale sign that that’s what you’re doing. If you lose more than that, eat some more. 

Again, not a plug and we’re not making money out of this, but MyFitnessPal helps you do that for free. 

Circling back to the topic of metabolism… 

3. You’re not burning enough calories

Let’s say you’re not consuming a lot of calories and you’re still not losing weight on intermittent fasting. The problem might be that your body just isn’t using enough energy. 

The fix? Exercise. 

It’s simple, really. Exercising gets you to move more and the more you move, the more calories you burn, giving you a better chance of losing weight. 

Not only that, there’s research showing how exercise helps counter the metabolism-slowing effects of a low calorie diet, making weight loss so much easier to do. 

If you want to know which type of exercise is best for weight loss, check out our work on cardio versus strength training

4. Maybe you’re not using the most suitable IF method for you

There’s a handful of ways you can do intermittent fasting (which we will get to later on) and all of them are effective ways to lose weight. 

However, not all of them are probably going to fit your specific lifestyle. And, to me, forcing it will only stall your weight loss, if not lead to even more unhealthy habits. 

For example, let’s say you try a more extreme method of IF with an eating window of just 4 hours per day. If you’re new to fasting, you’re probably going to be famished by the time you get to your eating window.

This leads us to…

What is the most effective fasting method for weight loss?

There’s 7 popular methods to do intermittent fasting. Some of them will have you fast for a certain number of hours while some will have you fast on certain days. We talk in more detail about them in another article but here’s the gist of it: 

  • 12:12
      • You fast for 12 hours and eat for the other 12. 
      • This way, you have plenty of time to get all 3 of your main meals but you probably won’t be able to snack before breakfast and after dinner. 
      • This is also probably one of the most beginner-friendly IF methods. 
  • 16:8
      • 16 hour fast with an 8-hour eating window. 
      • What’s typically recommended here is that you skip breakfast. You do get to eat your lunch and dinner though. 
      • This is more challenging but still fairly easy for beginners. 
  • 20:4 (a.k.a The Warrior Diet)
      • You fast for 20 hours (usually during daytime until afternoon) then you’re allowed to eat for the other 4 hours.
      • In my eyes, it’s definitely one of the most challenging ways to do intermittent fasting. 
  • 5:2
      • You eat like you normally would for 5 days but for the other 2, you’re only allowed to eat a quarter of your usual calories. 
      • It’s harder than 12:12 and 16:8 but some people find it easier than 20:4. So, I say it’s right around intermediate difficulty. 
  • Eat-Stop-Eat
      • Similar to 5:2 but instead of a 2-day fast, you get the equivalent of that in hours (48 hours). However, you should also split the 48 hours in half with at least 2 feeding days. 
      • This is generally more difficult than 5:2 but if you time your 24-hour fasting splits right, it shouldn’t be that much harder. 
  • Meal skipping
      • There’s no actual structure here. You just skip a meal whenever you can. Aim to skip 1-2 meals every week. 
      • Along with 12:12, this is probably one of the easiest ways to do intermittent fasting. 
  • Alternate-day fasting (ADF)
    • You fast every other day. 
    • On your fasting days, you can either consume a quarter of your normal calories, consume 500 calories in total, or not have any calories at all. 
    • I rank this as one of the most challenging methods of intermittent fasting, right up there with The Warrior Diet. 

Among all these, ADF seems to have the most potential for weight loss because you can literally cut your overall calorie intake in half. However, this relatively extreme method of fasting makes it very easy to overeat during your feeding days, so it might not be the best for everyone, particularly beginners who still don’t have enough control over their portions. 

On the other hand, meal skipping, 12:12, and 16:8 all seem very newbie-friendly. If fasting hours don’t work for you though, maybe fasting days will. In that case, 5:2 or eat-stop-eat might be your best bet. 

Bottom line is, the most effective fasting method for weight loss is the one that makes it the easiest to consume the right amount of calories for you to safely lose weight (1-2 lbs per week). It’s also the one that best fits your lifestyle and eating habits. 

So, if you think you’re losing weight too fast, too slow, or not at all, experiment with other versions of IF and see if that works for you. 

How to maximize weight loss on intermittent fasting

Aim to cut 3500-7000 calories from your normal weekly consumption

That’s the weekly equivalent of the calories you’re supposed to cut to lose 1-2 lbs of weight per week. 

I know, I know. I keep yapping about losing 1-2 lbs weekly but that’s because if you want to maximize your success on any diet, the CDC says losing your weight gradually is what’s going to help you keep the weight off. 

Realize that the quality of your calories matter

When you want to maximize your weight loss efforts, you have to understand that not all calories are the same. 

For example, let’s compare the calories and macronutrients in a cup of white rice and a cup of brown rice. (The data below comes from The Self NutritionData.)

  Calories Carbs Protein Fat
White rice 205 kcal 44.5 g 4.2 g 0.4 g
Brown rice 216 kcal 44.8 g 5.0 g 1.8 g

As you can see, both of them actually have similar macronutrients. However, what makes brown rice better for fasting is that it has a lower glycemic index (GI). 

According to an article from ScienceDaily, foods with lower GI such as brown rice take longer to digest, making you feel fuller for longer. This, in turn, should help dial down the cravings that may come with fasting. 

(For more examples, check out our list of natural appetite suppressant foods for weight loss.)

That being said, it’s also not just about curbing your appetite. It’s more about choosing food that gives you your share of nutrients despite being in a caloric deficit. This means eating clean and swapping out junk food without any real type of nutrition and, instead, opt for whole food. 

Schedule your workouts around the type of IF you’re doing

First of all, if you’re not exercising right now, you probably should. Doing any type of exercise is going to burn more calories than doing nothing at all, so it’s all going to help you lose weight.

However, if you want to know whether cardio or weight training is better for weight loss, that’s a topic for a different article. 

Nevertheless, you want to schedule your workouts to whatever type of IF you’re in. Specifically, you want to be working out during your feeding days. This gives you the fuel you need to maximize your sessions and the nutrients to kickstart your recovery. 

Now that we’ve discussed maximizing your weight loss results…

What happens when you stop intermittent fasting?

We’re talking full stop here, right? 

Because, well, nothing’s going to happen if you do decide to stop intermittent fasting. 

You read that right. Nothing. 

That is, of course, if you did intermittent fasting right in the first place. That means eating the right amount of calories, consuming nutritious sources of those calories during your feeding windows, and staying physically active. 

If you stop intermittent fasting and retain those habits, you aren’t going to gain any more weight and you still will enjoy the same health benefits. 

Now, if you did stop intermittent fasting and went back to your old unhealthy ways, that’s an entirely different story. You’d gain your weight back and you’d eventually lose the other health benefits, too. 

“But, what happens if I break intermittent fasting for a day?”

In that case, I’m assuming you just need a break from all the fasting and healthy eating and figured you’d indulge for a bit. Or maybe there’s an event you want to go to and you need to break your fast to enjoy your time with family and friends. 

I say go for it. Treat it as a cheat day. 

For one, your mental health and relationships matter, too. If being on intermittent fasting on that particular day doesn’t give you a sense of peace, then I personally don’t think it’s worth it. 

Second, a study from the International Journal of Obesity suggests that cheat days actually help you lose weight because it helps restart your presumably sluggish metabolism as a result of being on a low-calorie diet. 

From a mental standpoint, a study from the Journal of Consumer Psychology suggests that cheat days help you feel more motivated to pursue your goals, leading to greater long-term success. 

Oh, and speaking of long-term… 

Is intermittent fasting healthy long term?

The truth is that there’s a limited number of studies on the long-term effects of intermittent fasting, so what’s known about how healthy it can be for you over the years is still virtually unknown. 

However, what I do know is that the issues behind the possible long-term consequences of intermittent fasting lie mostly on how well people do their fast. 

For example, you won’t be able to sustain intermittent fasting for more than a few years if all you ate during your eating windows are empty calories. Eventually, you’re going to get sick and have to stop fasting altogether. In that case, eating clean, balanced meals on your feeding periods should help make IF more sustainable. 

Another issue is on how some dieters can’t seem to control their portions on their non-fasting days/hours. Here, you could either be eating too much or too little. Either way, both can be unhealthy and are therefore, again, unsustainable. 

I hate to repeat myself but a solution is to keep track of how many calories you consume and how much weight you lose per week. You could also switch to a different method of doing intermittent fasting and see if that works.

All in all though, I personally believe intermittent fasting can be sustainable long-term particularly if you pair it with healthy habits like regular exercise, clean eating, and portion control.

This brings us to the last part of our discussion. 

How to maintain weight loss after intermittent fasting

When you’ve finally reached your goal weight, you’re faced with the option of continuing down the fasting path or quit it entirely. 

If you choose to continue fasting intermittently, you maintain the benefit of feeling less hungry during your fasts. Only, in this case, you can eat more calories during your feeding window to keep your weight.

On the other hand, maintaining your weight while going back to a normal eating routine should still be very doable granted that you ate the needed amount of calories to maintain your weight. 

Regardless of whatever path you choose though, you should still keep all the healthy habits you picked up on your diet. That, to me, is true maintenance. 

Conclusion

Here’s a recap:

You can begin to lose weight after just 1 week of intermittent fasting but visible changes might not happen until after 8-10 weeks into your diet. However, there will be hurdles. 

For one, you might not even lose weight at all. There’s also the issue of longevity and choosing the right type of fasting method that best fits your lifestyle and schedule. Whatever problem you might encounter through your journey though, I hope I helped shed some light on a few possible solutions.

Adios! And please share this with a friend.

Article by:

Kristopher Ceniza

Kristopher Ceniza

I’m Kristopher, a writer for Sprout Origin. I’ve been writing professionally for quite a few years now but even before I pursued it as a career, writing has always been my safe haven. I’m also an avid gym-rat with a penchant for aesthetics and functionality, an ardent basketball fan, and a car/motorcycle enthusiast.

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