Why Am I Not Losing Weight on Intermittent Fasting?

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Key Takeaways

  • Intermittent fasting involves prescribed fasting and eating windows and is often used as a weight management strategy.
  • Intermittent fasting can help people naturally reduce calories without a specific calorie goal due to shortened eating windows. It also results in metabolic changes that can support weight loss goals. 
  • You may have difficulty losing weight with intermittent fasting if you’re eating too many calories, too few calories, or don’t have a balanced diet.

Intermittent fasting (IF) is a popular weight loss approach centered on changing when you eat rather than what you eat. There are many variations of IF, all involving specific fasting and eating windows throughout the week.

Though it’s a trendy eating plan, intermittent fasting does not guarantee weight loss.

There are factors to keep in mind to figure out why you might not be losing weight on intermittent fasting, such as eating too many or too few calories. 

The best way to figure out how to manage your weight is to talk with a registered dietitian about a sustainable, healthy plan.

Continue reading to learn more about intermittent fasting and how to maximize your results.


Why Am I Not Losing Weight on Intermittent Fasting?

Though weight management is a complex process, there are a few reasons to consider why intermittent fasting may not be working for you. 

Intermittent fasting plans do not come with calorie goals and it can be easy to overeat during your eating window.

This can happen especially in more restrictive IF plans (which are described below) because you may become overly hungry during your fasting window. 

While some people notice appetite increases, especially when starting with intermittent fasting, others experience appetite suppression.

This can result in a calorie intake that is too low, triggering a starvation response and halting weight loss.

You may want to experiment with your fasting and eating windows to find the right balance for you.

Even though intermittent fasting focuses on when you eat, your food choices still matter.

If you are not meeting your minimum nutritional needs during your eating window, especially for satiating nutrients like fat, protein, and fiber, you may find yourself more likely to break your fast out of hunger and low energy. 

Lastly, over consuming ultra-processed foods, like fast food and sugar-sweetened beverages, may also negatively impact your results.

These foods tend to be low-fiber and high-calorie, making it easy to overeat them. 

What is Intermittent Fasting?

Intermittent fasting is an eating plan that focuses on restricting the times you eat through specific fasting and eating windows. It does not involve calorie restriction or limitations on food choices. 

People follow intermittent fasting plans for many reasons, from weight loss to diabetes management to improving focus. 

The most common intermittent fasting plans are:

  • Time-restricted feeding, such as the 16:8 plan, which involves a 16-hour fast overnight with an eight-hour eating window each day. 
  • Alternate-day fasting, which is when a person fasts every other day for the whole day and eats unrestricted on the off days. 
  • 5:2 fasting, which involves eating 0-25% of your daily calorie needs two days per week and eating normally the other five days. 

How Does Intermittent Fasting Help Weight Loss?

Intermittent fasting can help weight management in two main ways. Firstly, most people will naturally eat fewer calories by restricting the hours they are allowed to eat, which can result in weight loss.

Interestingly, a 2020 systematic review of the studies on intermittent fasting and weight loss found that weight loss occurred even in people whose calorie intake did not change. However, longer, larger studies are needed to better understand this connection.

This may have to do with the body’s physiological response to fasting. In a fasted state, the body primarily burns fat for energy (rather than glucose). Research also shows that intermittent fasting may improve insulin resistance.  

Insulin resistance and chronic systemic inflammation have been linked with higher body weight, and intermittent fasting may impact weight by improving these markers. 

However, most research on intermittent fasting and weight loss is short-term. More studies are needed to understand its long-term effects and sustainability. 

How Do I Know If Intermittent Fasting Is Right for Me?

Research shows intermittent fasting is safe for most healthy adults and does not typically have serious side effects.

Many people prefer IF to other weight management strategies because it does not limit calories or food choices. 

However, intermittent fasting is not for everyone. The more restrictive variations that involve whole-day fasting may come with risks.

Talk to your doctor before starting intermittent fasting, especially if you are under 18 years old or have conditions like:

Research shows that the following side effects may occur while intermittent fasting, though it’s well tolerated by most people.

If you feel poorly on an intermittent fasting regimen, discontinue the plan and talk to your doctor about other options. 

  • Dizziness. 
  • Weakness. 
  • Headaches. 
  • Difficulty concentrating. 
  • Sleep disruptions. 
  • Nausea. 
  • Constipation. 

Tips for Making Intermittent Fasting Easier

If you’re new to intermittent fasting, consider the following tips to help with the transition. 

Ease Into It

Many intermittent fasting plans exist, some much more restrictive than others. It’s best to ease into IF, starting with a variation that feels realistic, then slowly increasing your fasting time. 

For example, research supports the 16:8 intermittent fasting plan both as an effective and sustainable option for many people.

You may consider starting with a 12-hour fast (such as 8 pm to 8 am) and working your way up to 16 hours as needed to see results. 

Consider Your Lifestyle

Keep your lifestyle in mind when selecting a plan. Time-restricted feeding plans work well for people who don’t have much appetite in the morning. Someone very active may struggle with whole-day fasting. 

Talk to a Registered Dietitian

A registered dietitian (RD) can help you identify the optimal intermittent fasting plan, if appropriate, while encouraging nutritious, balanced food choices.

An RD can also teach you meal planning strategies to ensure you make the most of your eating windows. 

Intermittent Fasting Alternatives for Weight Loss

If intermittent fasting is not for you, there are many other weight management strategies you can consider.

Talk with your doctor and a registered dietitian for further guidance on the best plan for you. 

Continuous Energy Restriction

Continuous energy restriction means you aim for a daily calorie deficit rather than fasting at specific times.

Studies comparing people following intermittent fasting versus calorie restriction have found that the two methods produce equivalent weight loss results. 

Continuous energy restriction is the most commonly suggested weight loss plan instead of intermittent fasting.

Intuitive Eating

If you want to improve your relationship with food, the quality of your diet, and your body image, a non-diet approach such as intuitive eating may be a good fit.

Intuitive eating is the practice of listening to your body’s natural hunger and fullness cues to guide your eating.

Though weight loss is not the primary focus of this approach, research shows that intuitive eating is associated with a lower BMI and improved psychological health.

It may also help improve other health markers, like blood pressure and cholesterol levels.  



Intermittent fasting encompasses a wide range of approaches, from time-restricted feeding to alternate-day fasting.

It can help with weight management because a smaller daily eating window can result in calorie reduction, and metabolic changes also occur while fasting. 

If you’re not seeing results with intermittent fasting, you may be eating too many or too few calories.

You might also want to examine your food choices and diet quality with the help of a registered dietitian. 

How a Dietitian Can Help

Whether you’re already practicing intermittent fasting or you’re interested in trying this approach, a registered dietitian can help you identify the most sustainable IF plan for your lifestyle while guiding you on food choices to support weight management.

A dietitian can also assist in troubleshooting if you don’t see results on IF. 


Frequently Asked Questions

Why is my weight not going down during intermittent fasting?

If you’ve been following an intermittent fasting plan for a few months without results, you may want to look at a couple of factors. First, are you overeating during your eating window? Too many calories and less nutritious food choices can hinder weight loss results. 

Some people consume too few calories on intermittent fasting, especially plans with longer fasting windows. This may trigger the starvation response, preventing weight loss.

Why is intermittent fasting not showing results?

If you’re doing intermittent fasting for weight loss, it can take time (sometimes up to a few months) to start seeing results. Under- or over-eating and poor diet quality can stop you from getting results.

Consider working with a registered dietitian to optimize your food choices and adjust your fasting and eating window times. You may need to try a few different intermittent fasting plans to find one your body responds to.

How long does it take to notice weight loss from intermittent fasting?

Research shows that it may take one to three months to notice weight loss from intermittent fasting because of the way fasting changes your metabolism. Some people notice weight loss sooner, especially if intermittent fasting creates a calorie deficit.


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