One of the most buzz-worthy diets going around is intermittent fasting (IF), aka time-restricted feeding (TRF), periodic fasting, or alternate-day fasting (ADF). It’s been praised by fitness gurus and trainers, wellness communities, social media influencers, doctors, celebrities, and ordinary people alike. And for good reason. Voluntary fasting has been part of the human experience for thousands of years, and the research on the health benefits of limiting the meals has recently been stacking up.

In fact, fasting for extended periods either daily or a couple of times a week can help:

• “Flip the switch” to improve metabolic function
• Increase insulin sensitivity
• Promote ketone production
• Optimize hormones
• Boost energy levels
• Improve fat burning and support greater weight loss
• Decrease belly fat (i.e., visceral fat)
• Promote youthfulness
• Support heart health
• Improve inflammatory marker levels (e.g., CRP, TNFa, IL-6)
• Improve resting heart rate and blood pressure
• Increase longevity
• And more.

No wonder so many people are jumping on the IF bandwagon! But just because it offers these types of benefits for many people doesn’t mean it’s the right diet for everyone. In fact, other people suffer more of the side effects of IF, which can include:

• Increased hunger and cravings
• Headaches
• Lightheadedness
• Digestive complaints, including nausea
• Fatigue
• And more.

Plus, it can also be difficult to fast for long periods, even if you really want to. If you’re one of the folks who suffers from side effects, you may have wondered if it’s you, the diet, or if intermittent fasting just isn’t right for you.

Here are some signs to watch for to help you determine if IF isn’t the diet for you. (And that’s okay.)

11 Signs Intermittent Fasting is Not For You

1. You Feel Sick

Especially on longer fasts, some common complaints include headaches (sometimes severe), lethargy, constipation, or other GI issues. For those who are battling or recovering from an illness, the immune system needs adequate calories to function well and maintain lean mass.

And if you begin IF and already struggle with digestive complaints, IF may make them worse by disrupting digestion, which can lead to bloating, heartburn, and constipation.

If your body feels sick, it’s time to reassess your fasting protocol. Perhaps you decrease the amount of time you fast or adjust how you fast (see below). Don’t ignore the signals, though, as this is important information letting you know it’s time to make adjustments or choose another type of diet all together.

2. You Overeat

If you find yourself overeating or binge-eating after your fasting period, you may undo any potential benefits. It’s human nature to eat when you’re hungry. You have hormones that increase your appetite when you aren’t eating enough or when your stomach has been left empty for prolonged periods. But if you over-indulge or eat unhealthy foods (especially uncontrollably) after fasting, you may increase your risk of developing disordered eating habits.

3. You Have a Medical Condition

Yes, IF can be beneficial for people with some medical conditions. For other conditions, though, IF can lead to complications. This includes people who have blood sugar issues, those who are underweight, and those on certain medications, including those for high blood pressure, kidney stones, reflux, malabsorption issues, thyroid problems, or diabetes.

For instance, if you have hypo or hyperglycemia (high or low blood sugar), IF can lead to more severe ups and downs, which can make symptoms worse. And if you’re currently using diabetic drugs to help control the issue, fasting can lead to dangerously low blood sugar levels.

If you have any medical conditions or are using any medications, please work with your doctor or another healthcare practitioner to ensure you are practicing IF safely.

Also, remember that some medications need to be taken with food to avoid stomach irritation or nausea. If you are on medications that need to be taken at specific times with foods, then IF is likely not right for you and your condition.

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4. It Causes Women’s Issues

For many women, restricting food intake to specific windows can lead to greater insulin sensitivity. This is a positive benefit. It allows your cells to more efficiently use food energy (e.g., sugar) and lowers blood sugar levels. It can, however, also affect hormones, including those important for fertility. If you’re pregnant, trying to get pregnant, or nursing, this isn’t the right time to practice IF. Likewise, if you have hormone imbalances, such as thyroid or adrenal issues, PMS, or period pain, IF can increase stress levels that lead to more side effects.

5. You’ve Lost Too Much Weight

A risk that’s especially common with older adults is losing too much weight. If you are already on the low end of the weight scale, IF can lead to too much weight loss, which can decrease bone mass, hinder immune functioning, and decrease energy levels. It can also lead to nutrient deficiencies or dangerously alter electrolyte balance, especially if the fast is extended.

For women, another risk is irregular or halted periods, which can indicate you’ve lost too much weight or dropped your calorie count too low. Another sign that your calories are dangerously low is hair loss.

6. Weight-Loss Results Have Stalled

If you’re using IF to help support your weight-loss efforts, then cutting calories too low can be counterproductive as it slows the metabolism, which can halt weight loss. If you are no longer seeing weight-loss results, give your body a break to get your metabolism revved up again.

7. You Feel Hangry

Feeling hungry, angry, and irritated at the same time is a real thing. When you try to ignore your hunger signals, it can lead to feeling just plain grumpy. IF can also lead to increased levels of the stress hormone cortisol, which makes it more difficult to lose fat.

It’s okay to admit that IF isn’t for you or to at least increase your eating window until you find a good balance of benefits without uncomfortable side effects. Feeling stressed and irritated due to your diet are good indications it’s not working well for you.

8. Difficulty Sleeping

Many people who practice IF find that they get some of the best sleep of their lives since eating right before bed can provide energy that keeps your brain active or makes your body feel restless. Others, however, find it impossible to get to sleep or stay asleep as their stomachs rumble. If IF isn’t helping you sleep, again it’s a sign that it’s time to make a change. After all, sleep is vitally important for brain functioning, emotional stability, decision-making, recovery, and weight loss.

9. You Always Feel Tired

Restricting calories means you’re restricting the fuel you may need, especially if you have a very active lifestyle. The body needs nutrients and optimal fuel to recover and grow stronger.

If you feel tired all the time, find it difficult to concentrate, don’t seem to recover as well from your workouts, or can’t seem to get enough sleep, it’s likely time to look at the types of foods you’re eating and move away from IF. At the very least, take a break to allow your body to better recover.

10. You Have Disordered Eating

While IF has many benefits, it also can shine a powerful spotlight on your eating, so it’s not a good diet for those who have suffered from disordered eating—including bingeing, bulimia, or anorexia. Especially if you strive for perfection or have impulsivity or mood challenges, severe dietary restrictions like IF can quickly descend into disordered eating.

Another type of eating disorder is orthorexia, which is defined by an obsession with healthy eating. If you’re fixated on only eating healthy foods or you’re preoccupied with your diet or next meal and are inflexible with your eating even in social situations, this is a sign of dysfunction that needs to be addressed.

Self-shaming or guilt about eating too early or too late, or anxiety or depression around the diet and how you’re following it are early signs of disordered behaviors. Get ahead of those emotions to ensure you aren’t developing orthorexia or another eating disorder.

If you do decide to give IF a try and you’ve experienced disordered eating in the past, do so only under the careful supervision of a healthcare professional you trust, who can help you navigate toward a healthier and more fulfilling relationship with food.

11. It’s Hard to Follow

People who love IF often talk about how much easier it makes eating. They save on groceries, cut back on the time it takes to cook and eat meals, and feel energized, and don’t even miss meals.

For folks who hate IF, it often comes down to being too hard to stay on track. They’re determined to give it a try but find themselves accidentally eating during their fasting windows or intentionally “cheating” because they just don’t feel all that good.

Learning how to trust and honor your hunger cues can be challenging if you’ve dieted for a long time. But it’s important to get back in touch with your hunger and understand when your body needs fuel versus when you’re eating for distraction or to cover up unwanted emotions. (But that’s a whole ‘nother topic.)

Fortunately, you have a lot of healthy options when it comes to eating. You don’t need to follow a dieting practice that doesn’t make you feel good.

How to Practice Intermittent Fasting Safely

It can also take a little time to get used to intermittent fasting. So, you don’t necessarily need to give up right away if it’s been challenging. If you’re struggling with side effects, there are some tips to help your body acclimate, such as:

• Stay hydrated by drinking plenty of water and other calorie-free beverages, such as water, tea, and black coffee.
• Start slowly—ease into IF by gradually decreasing the eating window over several months. For example, start with a 12-hour feeding window, eating only between the hours of 8 am and 8 pm. Then slowly lower—in 15- to 30-minute increments—down to a 10-hour window (e.g., 8 am to 6 pm). Continue the process until you reach your body’s preferred fasting window.
• Adjust your feeding window: one study found when a small group of obese men restricted meals to earlier in the day (7 am to 3 pm) versus over 12 hours (7 am to 7 pm), not only did they see decreased insulin levels and increased insulin sensitivity, they also experienced lower blood pressure. Plus, they enjoyed decreased appetite, which made it easier to stick with IF.
• Avoid obsessing over food by giving yourself healthy distractions, such as catching up on work, going to a movie, going for a stroll, drinking more water or a cup of tea, relaxing with friends, etc.
• During the fasted window, replace strenuous activities with light exercise, such as a stroll or gentle yoga.
• Stick to your medication regimen as recommended by your healthcare team, choosing a modified fasting plan if necessary.
• Pack your meals with nutrient-dense foods that provide quality proteins, abundant fibers, healthy fats, and vitamins and minerals, such as beans, lentils, eggs, fatty fish, nuts, and avocados. In addition, high-volume foods can help you feel fuller for longer without adding a lot of calories. Good choices include water-rich vegetables and fruits and low-calorie carbohydrates like popcorn. And avoid sugars, refined grains, and ultra-processed oils.
• Eat foods that are high in flavor by generously using low-calorie herbs, spices, and vinegar.
• Stay active and include muscle-building exercises in your routine.
• Add MCT oils like Keto Elevate to your plan, which may help you flip the switch but provide greater levels of energy and mental clarity with minimal additional calories. They may also help you stay in ketosis despite consuming calories during your “fasting” window.

What if IF Isn’t Right For You?

There’s no diet that’s right for all people all of the time. If you find intermittent fasting makes you feel a-mazing, then stick with it. But if it doesn’t, that’s okay too. Perhaps IF is a routine that makes you feel great until it doesn’t. Again, it’s also okay to switch things up.

Other diets that have been shown to improve overall health include the Mediterranean Diet, the DASH Diet, the MIND Diet, etc. The key is not necessarily when you eat but what and how you eat. Filling your menu with whole, nutrient-dense foods like quality proteins, healthy fats, complex carbohydrates, and loads of vegetables and eating mindfully has been shown time and time again to boost health.

Whether you’re following IF or not, it’s important to listen to your body, learn to understand hunger cues, and provide your body with the fuel it needs to maintain your active lifestyle. So, choose a diet that fits into your life, that you enjoy, and that you can sustain over time. Yes, it’s a lifestyle. If your current diet is difficult or makes you feel horrible, it won’t work for you long-term, no matter how many other people sing its praises.

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