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8 Root Causes for Not Losing Weight On Intermittent Fasting [Solutions Included]

13 min read
not losing weight intermittent fasting
Melissa Mitri post Reviewer Melissa Mitri post Reviewer
Verified by Melissa Mitri
MS, Registered Dietitian, Former President of CT Academy of Nutrition & Dietetics

Why are you not losing weight while on intermittent fasting? Read on to learn more about what you can do to fix this.

Table of Contents

Intermittent fasting (IF) is an approach that restricts the time that you eat rather than limiting the number of calories or types of food you can eat.

Many people follow intermittent fasting to lose weight, but in some cases, it might not work the way you want. 

If you’re not losing weight with intermittent fasting or if your weight has plateaued, there can be many underlying reasons. In this article, we discuss 8 root causes for not losing weight on intermittent fasting and what you can do to overcome them. 

Is Intermittent Fasting a Good Weight Loss Strategy?

In a nutshell, intermittent fasting means alternating between eating and fasting windows without restricting calories or the types of foods you can eat. There are many intermittent fasting types to choose from. The most popular ones are 16/8 and 14/10; however, there are also stricter ones like 18/6 fasting, 20/4, and even 24-hour and 36-hour fasts.

The principle behind how IF promotes weight loss is simple. To gain more understanding,  let’s take a quick look at how your body uses and stores energy.

The food you eat gets broken down into smaller particles that your cells can use to produce energy. For instance, carbohydrates get broken down into glucose. The excess glucose is then stored as glycogen for future use. 

This extra energy also gets stored as fat in your adipose tissue (i.e., fat tissue), making you gain weight. Your body primarily uses carbs and sugar for energy production.   

But if there is not enough sugar in the bloodstream, it begins by breaking down stored fat [1]. The breaking down of fat produces compounds called ketone bodies, and this phase is known as ketosis. 

During your fasting stage, blood glucose levels fall, thus bringing down insulin levels [2]. Glycogen stores get depleted, and ketosis kicks in. This makes your body burn fat, thus, in theory, promoting weight loss. 

Research studies “Effects of intermittent fasting on body composition and clinical health markers in humans” by Grant M. Tinsley and Paul M. La Bounty, “Effectiveness of Intermittent Fasting and Time-Restricted Feeding Compared to Continuous Energy Restriction for Weight Loss” by Corey A. Rynders, Elizabeth A. Thomas have confirmed the effectiveness of intermittent fasting for weight loss. One review, “Do Intermittent Diets Provide Physiological Benefits Over Continuous Diets for Weight Loss? A Systematic Review of Clinical Trials, Molecular and Cellular Endocrinology,” from 2015 by Radhika V. Seimon and Jessica A. Roekenes, which summarizes 40 studies, reported that intermittent fasting produced a weight loss of 7-11 pounds over 10 weeks.

Other Proven Benefits of Intermittent Fasting

On the other hand, IF has also been found to bring about many health benefits in addition to weight loss.

Research “Effects of Intermittent Fasting on Health, Aging, and Disease” by Rafael de Cabo, Ph.D., and Mark P. Mattson, Ph.D., shows that intermittent fasting can improve diabetes, heart disease, and cancer.
The studies “Intermittent Fasting Confers Protection in CNS Autoimmunity by Altering the Gut Microbiota” by Francesca Cignarella and C. Cantoni, along with “Effects of Intermittent Fasting Diets on Plasma Concentrations of Inflammatory Biomarkers: A Systematic Review and Meta-Analysis of Randomized Controlled Trials” by Xiaoli Wang and Qing-qing Yang, demonstrate that intermittent fasting can reduce inflammation. This reduction in inflammation can aid in managing conditions related to inflammation, such as Alzheimer’s disease, asthma, and multiple sclerosis.

Intermittent fasting has also been reported to reduce insulin resistance. This is supported by the study “Early Time-Restricted Feeding Improves Insulin Sensitivity, Blood Pressure, and Oxidative Stress Even without Weight Loss in Men with Prediabetes” by Elizabeth F. Sutton et al., published in Cell Metabolism Journal.

Side Effects of Intermittent Fasting

Intermittent fasting is a relatively safe regimen as it allows for sustaining a nutritious diet. However, despite the proven benefits, there are some side effects you should be aware of, especially when it comes to longer fasts.

The most common side effects of IF include:

  • hunger and cravings (these are common for the first days of practicing IF and fade when you start getting used to it),
  • headaches,
  • fatigue,
  • digestive issues like diarrhea, bloating, or constipation,
  • malnutrition and deficiencies can develop as a result of intermittent fasting. This is highlighted in the study “Clinical Management of Intermittent Fasting in Patients with Diabetes Mellitus” by Martin M. Grajower and Benjamin D. Horne, published in Nutrients on April 18, 2019..

Strict intermittent fasting regimens can also trigger eating disorders in prone individuals.

So, Why Am I Not Losing Weight on Intermittent Fasting?

While intermittent fasting (IF) can be an effective and healthy weight-loss strategy when done correctly, there’s no guarantee of weight loss by merely restricting your eating window. This point is particularly relevant for milder fasts like the 16/8 or 14/10 methods, which allow for eating three full meals and even snacking in between. Grant M. Tinsley and Paul M. La Bounty illustrate this in their study, “Effects of intermittent fasting on body composition and clinical health markers in humans,” published in Nutrition Reviews. They suggest that the success of IF in weight management depends on various factors, including the quality and quantity of food consumed during the eating periods.

The most common reason people fail to lose weight while intermittent fasting is still eating in a calorie surplus. It can happen due to various reasons, starting from wrong diet choices and ending with choosing the wrong IF type for you.

Below, we discuss the most common reasons of not losing weight while intermittent fasting in detail.

8 Reasons You May Not Lose Weight During Intermittent Fasting

Most people who turn to IF as a solution for weight loss seem to love it because it’s easier to follow than other restrictive diets.

IF doesn’t restrict what you eat; it doesn’t even limit how much you eat. This helps many people stick to the program for longer and increases the chance of success.

Some people, however, may not lose weight with intermittent fasting. Some may even give up the regimen altogether, thinking it’s not for them. But it’s better to hit pause, re-evaluate your approach, and try to work out what impedes success. 

Here, we discuss 8 possible reasons that can hinder your weight loss during intermittent fasting. We also provide actionable steps to make it work for you. 

You’re Not Giving it Enough Time

While IF is a proven way to lose weight, it doesn’t necessarily provide overnight results.

The consensus is it takes 2-10 weeks to lose weight with IF, and progress can vary for each individual. 

If you just started an IF regimen, but you’re worried that your scale is not budging, maybe you need to give your body more time to get adjusted. 

You’re Eating Too Many Calories During The Eating Window

While IF doesn’t restrict the number of calories you eat during your eating period, that doesn’t mean you should overstuff your calories. 

After all, a caloric deficit is what causes weight loss, and that’s not going to happen if your calorie intake exceeds your daily caloric needs during your eating window. 

People usually eat too many calories by having a lot of ultra-processed foods throughout the day. We won’t tell you to eliminate your cravings completely, but ensure the following:

  • your diet complies with the 80/20 rule, where 80% is healthy, nutritious meals, and 20% are your cravings that might include ultra-processed foods;
  • you are in a calorie deficit–10 to 20% deficit is optimal for safe weight loss.

You’re Not Eating Enough During Your Eating Window

We know this contradicts what we just said, but hear us out. 

If you don’t eat enough food to keep you satiated during your eating window, there’s a high chance that you will feel starved during the fasting period. 

While it’s inevitable to feel somewhat hungry during the fasting window—especially if you’re just starting your IF journey—you’re not supposed to constantly feel ravenous during this time. 

If you’re hungry all the time, you will end up snacking—even during your fasting window—which will break the fast and eventually lead to weight gain.

You’re Not Eating Enough Protein and Fiber

While it’s true that IF rules don’t dictate which foods to eat, you should still choose your diet choices wisely. One aspect that influences weight loss along with caloric intake is the type of food you’re eating. 

If your diet is mostly composed of simple carbs, you’re more likely to feel hungry soon after eating. 

High-glycemic index (GI) foods, such as refined breakfast cereals, white rice, pasta, and candy bars, cause rapid increases in blood glucose levels, which are followed by immediate declines in blood sugar. These fluctuations are thought to trigger hunger and promote overeating, as discussed by Susan B. Roberts in “High-glycemic index foods, hunger, and obesity: is there a connection?” published in Nutrition Reviews in June 2000. 

On the other hand, protein and fiber will keep you fuller for longer, thus managing hunger and curbing overeating [10].

If you’re not eating enough protein and fiber, it means you will feel hungry sooner than intended, and you’re more likely to snack within your fasting period. Needless to say, this will hinder your weight loss success.

Your Fasting Window is Too Short

There are many intermittent fasting practices, such as 16/8, 5:2, and alternate-day fasting. While you can choose the fasting duration that suits your lifestyle, following a too-short fasting window can deter your success. 

When you fast for shorter durations, your body doesn’t have enough time to go into ketosis. This means it won’t burn stored fat, and there won’t be significant weight loss.

As concluded in a study by Kahleova H, Lloren JI, Mashchak A, Hill M, and Fraser GE, titled “Meal Frequency and Timing Are Associated with Changes in Body Mass Index in Adventist Health Study 2,” published in the Journal of Nutrition in September 2017, a fasting window of 18-19 hours is more effective for weight loss compared to shorter fasting windows ranging from 12-17 hours. This research highlights the impact of extending the fasting period on weight management efforts.

Your Fasting Window Is Too Long

Again, this might sound confusing, but let us explain. 

Fasting for long hours certainly can benefit you when it comes to weight loss. However, it can also mean you need more willpower to sustain extended periods of hunger. 

It might not be a problem if you’ve been practicing IF for a long time, but if you’re a beginner, this might be an issue. In such a case, you’re more likely to give in and break your fast earlier than intended, thus introducing excess calories. 

If this happens frequently enough, you’ll not lose weight. On the contrary, it might increase your risk of weight gain. For best results, start with a shorter fasting window, and as you adjust, you can extend your fasting window time to encourage weight loss.

You’re Not Getting Enough Sleep

While this might seem unrelated to intermittent fasting, adequate sleep indeed plays a significant role in weight loss. The study “Insufficient Sleep Undermines Dietary Efforts to Reduce Adiposity” by Nedeltcheva AV, Kilkus JM, Imperial J, Schoeller DA, and Penev PD, published in the Annals of Internal Medicine on October 5, 2010, reported that sleep deprivation reduces the effectiveness of dietary interventions for weight loss.

Lack of enough sleep also affects your resolutions to stick to your regimen and makes it more likely to give in to temptations. It can also affect your mood, thus increasing episodes of emotional eating. 

You’re Not Drinking Enough Water

Hydration might seem unrelated at first glance, but there’s scientific evidence showing that drinking water can boost weight loss during diets with restricted calorie intake. This was highlighted in the study “Water Consumption Increases Weight Loss During a Hypocaloric Diet Intervention in Middle-aged and Older Adults” by Dennis EA, Dengo AL, Comber DL, Flack KD, Savla J, Davy KP, Davy BM, published in the journal Obesity in February 2010.

This is because water reduces calorie intake during meals and keeps you full during fasting hours. Water can also substitute high-calorie beverages such as cola drinks and fruit juices, thus effectively reducing calorie consumption.

Not drinking enough water can leave you feeling less full and make you overeat.

Here is What to Do If You Cannot Lose Weight on IF

You now probably have a good idea of how to resolve the issues we spoke about above, but let us provide a refresher.

If you’re fasting but not losing weight, you can try these tips to increase your weight loss success and make your intermittent fasting journey easier and more pleasant.

  • Be patient. You may not lose weight overnight or sometimes even in a couple of weeks. Give it enough time to see sustainable results. Meanwhile, maintain a journal to keep track of your progress and to evaluate the process.
  • Eat a balanced meal. It may require changing your eating habits but, if done correctly, it’s not as hard as may sound. As a minimum, include healthy portions of proteins and fiber to keep you full during fasting hours.
  • Eat enough food to keep you satiated, but don’t eat too many calories. To achieve that, introduce high-volume, low-calorie foods into your diet. You can also try a weight-loss app to calculate your daily caloric needs for weight loss.
  • Choose a fasting window that easily fits into your schedule. Make sure it’s not too short, but if you’re just starting out, you can start slow and increase the hours as you move further down the journey. 
  • Aim to get at least 8 hours of sleep each night.
  • Drink plenty of water, especially during the fasting window. Also, try other zero-calorie drinks allowed during fasting.

Wrapping Up

Although considered a surefire way to weight loss, not everyone loses weight with intermittent fasting. However, that doesn’t mean you should stop your fasting practice immediately. 

Hit pause first and evaluate your routine to see if you’re making any of the mistakes we’ve discussed above. Try our tips to fix them, and also make sure to review your progress with your nutritionist. 

This being said, you might want to avoid intermittent fasting if you’re pregnant or breastfeeding. If you have long-term health issues such as diabetes or thyroid issues, it’s best to consult your doctor before starting intermittent fasting.

Disclaimer This article is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional advice or help and should not be relied on to make decisions of any kind. Any action you take upon the information presented in this article is strictly at your own risk and responsibility!

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