Intermittent Fasting: Is It Worth It? Real Answers 2025
Intermittent Fasting (IF) is a different kind of dieting, focusing more on when you eat rather than what you eat or how much. The name comes from its nature – a pattern that cycles between periods of eating and not eating.
Over the last few years, IF has gone from niche to mainstream, with fans swearing by everything from the 16:8 method to alternate-day fasting. Some say it helped them shed stubborn pounds, while others praise its potential perks for energy, focus, and even longevity.
But is intermittent fasting really that great? With the help of our in-house nutritionist, I cracked open the IF trend, and I’ll break everything down for you in this well-researched and comprehensive guide. So stay tuned until the end to learn everything there is about IF!
What Is Intermittent Fasting, & How Does It Work?
Think of intermittent fasting as a time-based eating strategy, not a classical diet. Instead of obsessing over carbs or calories, IF focuses on when you eat rather than what you eat. You cycle between periods of eating and fasting, when you don’t eat anything or eat very little.
Unlike classic calorie restriction, where you're trimming portions all day, IF gives your body longer breaks from digestion, which some research suggests might have benefits beyond the scale1. It’s worth noting that many of these benefits of IF are mediated by the weight loss that often comes with IF.
Types of Intermittent Fasting
The good news is that there’s no one-size-fits-all when it comes to intermittent fasting. Different approaches suit different lifestyles, hunger cues, and goals. You can even design your own methods, but if you’re looking for inspiration, here are the most popular types:
What You Can Eat
Can you really eat anything while intermittent fasting? It depends on the results you want and whether you’re in a fasting period or an eating window. Let’s break it down.
During Fasting Periods 🚫
During fasting periods, it’s all about keeping things minimal. You’re not eating, but hydration is your best friend.
Here’s what you can (and should) have:
Water: plain, sparkling, mineral, flavored, or any kind that fits your fancy.
Black coffee: no milk, no sugar, just the hard stuff.
Unsweetened tea: herbal, green, black – your choice, just skip the honey and cream.
Pro tip: If you’re feeling hangry, a glass of water might just save the day.
During Eating Windows ✅
Technically, intermittent fasting doesn’t dictate what you eat. However, you shouldn’t jump straight into a donut binge if the purpose of this diet is to lose weight and stay healthy.
Focus on a balanced diet and aim for foods that fuel your body and keep you full, such as:
Veggies and fruits: fiber, vitamins, all the good stuff.
Lean proteins: chicken, tofu, fish, eggs.
Healthy fats: avocado, olive oil, nuts.
Whole grains: brown rice, quinoa, oats.
Health Benefits of Intermittent Fasting
While intermittent fasting has gained a reputation as a miracle fix for just about everything, the truth is a bit more nuanced. Yes, there’s promising research out there, but scientists are still debating how big the benefits actually are.
That said, many people report positive changes, especially in terms of weight and energy.
Weight Loss
The main benefit reported by IF followers is weight loss2,3. This is not surprising since the method helps reduce your overall calorie intake. Fewer meals mean fewer opportunities to snack your way through a bag of chips at midnight.
Many healthcare professionals agree that IF can be an effective tool for managing weight. But we have to see it for what it is – a tool – and not some magical fat-melting switch. The weight loss comes from a calorie deficit, just like every other diet under the sun.
What makes IF different is that, for some people, it’s a lot easier to stick to. Less micromanaging meals, more freedom. Studies show that there’s better IF adherence compared to typical calorie restriction methods4.
Improved Metabolic Health5
Research suggests that IF can improve insulin sensitivity. This means your body becomes better at processing glucose (aka blood sugar), which is especially helpful for people at risk of type 2 diabetes or those trying to stabilize energy levels throughout the day.
Fasting gives your body a break from constant digestion and insulin production, which might help lower inflammation, a sneaky culprit behind many chronic diseases.
Furthermore, recent studies show that people who practice IF have better lipid profiles4. Some participants registered a reduction in triglycerides and LDL (bad cholesterol), and an increase in HDL (good cholesterol), which usually leads to improved cardiovascular and metabolic health.
During longer fasting periods, the body switches from using glucose (sugar) as its main fuel source to using stored fat (a process called metabolic switching6). This can lead to loss of visceral fat (adipose tissue around organs), which is strongly linked to metabolic disease.
Still, it’s important to remember that fasting is not the only factor at play here. Sleep, stress management, and a balanced diet are also important. Intermittent fasting is not a cure-all, but it can amplify the health benefits of good dietary habits.
Cellular Repair & Muscle Gain
One of the body’s responses to fasting is a process called autophagy7,8. Think of it as your body’s version of spring cleaning: it breaks down and recycles damaged cells, clearing out the cellular clutter that can build up over time.
Some researchers believe this cellular cleanup may play a role in healthy aging and disease prevention9.
Brain Health10
Do you feel like you go into a food coma after your lunch? While it’s normal to experience a dip in energy after lunch, it’s not natural to not be able to hold your head up after your meal. This usually indicates that your meal might have been too heavy or that other factors are at play.
If you think your lunch might be the issue, intermittent fasting may help. Many IF fans swear by the mental clarity and laser-like focus they feel during fasting periods. Furthermore, some studies suggest IF could sharpen memory and cognitive function11, especially as you age.
Fasting may increase the production of brain-derived neurotrophic factor12 (BDNF), a protein that supports neuron growth and protects against cognitive decline. Also, when you're fasting, your body starts tapping into stored fat for energy. One byproduct of that is ketones, which some researchers believe are a super fuel for your brain. As an example, drastically reducing carbohydrate and protein intake and replacing them with fats puts the body into ketogenesis and has been found to be a way to control epileptic seizures13,14.
But it’s not just about skipping meals; pairing IF with a nutrient-rich diet during eating windows can fuel your brain for optimal performance.
Longevity
Studies, mostly in animals, suggest IF might extend lifespan15,16 by reducing the risk of age-related diseases like heart disease, diabetes, and even certain cancers17.
The theory says that fasting stresses your cells in a good way, boosting their resilience and triggering protective processes like autophagy (that cellular cleanup we mentioned). This could slow down the aging clock and keep chronic illnesses at bay.
That said, we’re still waiting on more long-term human studies to say for sure. So, while it’s not a guaranteed ticket to centenarian status, intermittent fasting could be one piece of the puzzle for healthy aging, alongside sleep, movement, good genes, and other factors.
Side Effects & Risks
Let’s be clear: intermittent fasting isn’t magic, it’s not a miracle, and most importantly, it’s not for everyone.
Plenty of people swear by it, but there are still people who try it and realize it’s not their cup of tea. And that’s totally okay. Like with everything in life, there are caveats and downsides to intermittent fasting.
Here are some common side effects and risks to keep in mind:
Hunger & Irritability 😫
The infamous “hangry” feeling is real, especially in the beginning. Your body needs time to adjust, and until it does, don’t be surprised if small things make you irrationally mad18. Like your coworker breathing too loudly or your partner chewing their food a bit too aggressively.
Headaches & Dizziness 😵💫
These can pop up during the early days of fasting19, particularly if you’re not staying hydrated or are skipping electrolytes. Salt, water, and patience can go a long way.
Fatigue 🥱
If you’re not eating enough or not eating well during your eating window, you might feel drained20. IF isn’t an excuse to skip meals and skimp on nutrients! Your body needs fuel to function, so don’t take any chances.
Overeating 🍽️
IF is also not an excuse to binge on whatever unhealthy foods you dream of during the fasting period. Pay attention to the “I deserve this” mentality, especially if you’re ravenous. Bingeing can undo a lot of the benefits and leave you feeling sluggish.
Discomfort 😖
Going without food for too long can lead to low energy, digestive discomfort, mood swings, and that familiar 'hollow-stomach' feeling that nobody enjoys. Listen to your body – if fasting feels more like torture than balance, it might not be the right fit.
Who Should Avoid Intermittent Fasting?
Intermittent fasting can work wonders for certain groups, but this doesn’t make it a one-size-fits-all method for weight loss and/or improved brain function. In fact, some people should steer clear of it or approach it cautiously.
For starters, here’s who might want to skip it or get professional advice first:
People With Certain Medical Conditions ❤️🩹
If you have diabetes, low blood pressure, a history of eating disorders, or take medications that require food, talk to your doctor first. Fasting can mess with blood sugar levels and medications, and that’s not something to DIY.
Pregnant or Breastfeeding Women 🤰🏻
Your body is doing incredible work, and it needs all the fuel it can get. Fasting during this time can interfere with both your health and your baby’s development, so this is a solid hard pass.
Athletes & Highly Active Individuals 🏋🏻
If you’re training hard or doing endurance workouts, fasting might not give you the energy you need. Some athletes make it work with careful meal timing, but it’s not ideal for everyone. Listen to your performance and your trainer.
Anyone Else 🤔
Your health, lifestyle, and personal preferences play a big role in whether IF is right for you. If it feels restrictive, stressful, or just plain annoying, there’s no shame in skipping it. The best diet is the one that fits your life, your schedule, and your sanity. IF is a tool, not a requirement.
How to Start: Intermittent Fasting for Beginners
If you’ve decided to give intermittent fasting a whirl, here are a few steps to help you start things off on the right foot.
Choose a Method That Fits Your Life
Don’t dive in headfirst. Start smart and choose a beginner-friendly method.
For instance, the 12:12 method (12 hours of fasting, 12 hours of eating) is a great intro because it’s the closest to our natural way of eating. You stop eating after dinner (let’s say 9 p.m.) and start again at breakfast time (around 9 a.m.). Easy peasy, right?
Once that feels natural, you can experiment with longer windows like 14:10 or 16:8. Remember, the best method is the one you’ll actually stick to.
Stay Hydrated
Water is your best friend during fasting hours. Herbal tea and black coffee are also fair game, but don’t overdo it since caffeine has a diuretic effect. Hydration helps curb hunger and keeps headaches at bay.
Eat Real, Nutritious Food
Fasting isn’t a free pass to load up on chips and cookies during your eating window. Think whole foods, lean proteins, healthy fats, fruits, and veggies. A balanced plate means you’ll have better energy, a better mood, and better results.
Skip the junk food as much as possible and focus on nutritious and fulfilling foods that will keep hunger at bay for more than a couple of hours.
Monitor How You Feel
Your body’s going to send you signals, especially during the first phase of the diet, so listen to them.
If you’re feeling overly tired, cranky, or dizzy, it may be a sign that the method you’ve adopted is too drastic. Change your approach by decreasing the fasting window and see if there are any improvements.
It’s also a good idea to take breaks when you feel your body can’t cope with IF any longer. You can always restart when you feel better.
Everyday Challenges & Solutions
Intermittent fasting sounds great on paper, but life doesn’t always play along. From going out to eat to workplace hurdles, it’s not always easy to stick to your fasting schedule. But, with a bit of imagination and smarts, it’s easy to find solutions to even the most challenging hurdles.
Here are a few ideas:
Social Events & Family Meals 🎉
Dinner parties or family gatherings can throw your fasting window out of whack, so learn to plan ahead.
If you know a big meal is coming, adjust your fasting window that day (maybe start your fast earlier or extend it slightly the next day). You can also eat lighter, nutrient-dense foods during your window to stay satisfied without overdoing it.
Coffee/Tea & Hunger ☕
Black coffee or unsweetened tea is IF-approved, but they can sometimes make you hungrier. I, for instance, get super-hungry after my morning cup of coffee.
If this is your case, and you want to try intermittent fasting, it’s best to cut out coffee and caffeinated drinks from your daily routine entirely. Switch to herbal teas, like peppermint or chamomile, since they’re soothing and less likely to trigger hunger.
Medication Timing 💊
Some medications need to be taken with food, which can clash with fasting. Talk to your doctor about timing your doses to fit your eating window, but if that’s not possible, prioritize your health. Take meds as prescribed, even if it means a shorter fast.
Workplace Integration 👩🏻💻
Conventional fasting windows (like 16:8 during daylight hours) can be tough if you’re awake all night. But flexibility is one of the reasons why IF is so popular. You can customize your schedule to fit your needs.
In this case, forget about regular circadian rhythms and fast when you’re sleeping (even if it’s during the day) and eat during your active hours. For example, a 12:12 method could mean eating from 6 p.m. to 6 a.m. if that’s your “day.”
But it’s not just nighttime workers who face challenges. Life at the office will also test your resolution with yummy snacks at the exact wrong time.
Politely decline snacks or bring a water bottle to sip during meetings. If hunger hits, try a shorter fasting window (like 14:10) on busy days. You can also schedule your eating window to start right after morning commitments.
Myths & Misconceptions
Any diet that reaches the level of “miracle” or “super-diet” is surrounded by myths and misconceptions. IF isn’t a magic bullet, but it’s a solid tool for a healthy lifestyle when used correctly, which is why it’s important to be aware of the false claims surrounding it.
I found and debunked some of the most common ones:
“Fasting slows down metabolism.”
Some worry that fasting puts your body into “starvation mode,” which can tank your metabolism. In reality, short-term fasting can boost your metabolic rate slightly, thanks to increased norepinephrine levels. This has been proven in a study from 200021, although it is worth noting that the study group was only 11 people.
Studies show IF doesn’t slow you down5 as long as you’re eating enough during your windows. Keep your meals nutrient-rich, and your metabolism will run smoothly.
“You’ll lose muscle.”
Not necessarily. The fear of wasting away muscle is real, but IF can preserve muscle mass if you prioritize protein-rich foods22 (like eggs, fish, or lentils) during eating windows. Pair your diet with resistance training, and you’re golden.
“You need to eat breakfast to be healthy.”
This one’s been drilled into us forever, but there’s no solid scientific evidence23 saying breakfast is a must for everyone. Many people skip breakfast naturally (without intentionally practicing intermittent fasting), and there’s no harm to their health as long as their overall diet is balanced.
So, if breakfast works for you, great – but it’s not a universal rule.
Concerns About Hunger, Energy, & Nutrients
First, let’s make one thing clear: you will feel hungry and even a little dizzy during the first few days of intermittent fasting. Your body is adjusting, rather abruptly, to a new way of fueling, and these are the signals it sends.
However, as things progress, these signals should subside. You may also feel sluggish or experience a surge of focus during certain times of the fasting window. If you don’t fill your eating windows with junk and focus on whole foods like veggies, lean proteins, and healthy fats, these swings in energy should stabilize pretty quickly.
FAQ
Can I drink coffee or tea during fasting?
Yes, you can sip black coffee or unsweetened tea during fasting periods – they’re calorie-free and won’t break your fast. They might even curb hunger and boost focus. If caffeine makes you jittery or hungrier, try herbal tea or water instead.
Will I lose muscle mass?
Not if you play it smart. Intermittent fasting can preserve muscle if you eat enough protein (like chicken or beans) during eating windows and include resistance training. Studies show muscle loss is tied to calorie deficits, not fasting itself.
Can I work out while fasting?
You can exercise while fasting, and many do! Light cardio or strength training works well, but intense sessions need proper fuel. If you feel dizzy, eat a small meal in your eating window before training. Don’t forget to hydrate properly!
How long does it take to see results?
Results vary, but most notice changes in 2 to 4 weeks. Keep in mind that factors like diet quality, fasting method, and activity level matter. Track progress with a journal or scale, but don’t obsess; sustainable changes take time.
Can I take supplements or medications during my fasting window?
Most supplements and medications are fine during fasting, but check with your doctor. Calorie-free supplements (like vitamins) won’t break a fast, but some meds need food. Time them with your eating window if possible.
How do I know if intermittent fasting is working?
Signs that IF is working include weight loss, better energy, improved focus, or stable blood sugar. If you feel good and see progress in 4 to 8 weeks, it means your efforts are working. For clear results, track metrics like weight, waist size, or how you feel.
Can I combine intermittent fasting with other diets?
Yes, IF pairs well with diets like keto, paleo, or Mediterranean, as it’s about when you eat, not what. But make sure to focus on nutrient-dense foods during eating windows to align with your diet’s goals. If you’re not sure how things work, consult a nutritionist.
References
1. https://pmc.ncbi.nlm.nih.gov/articles/PMC9946909/
2. https://www.annualreviews.org/content/journals/10.1146/annurev-nutr-071816-064634
3. https://pmc.ncbi.nlm.nih.gov/articles/PMC9998115/#sec5
4. https://pubmed.ncbi.nlm.nih.gov/38276554/
5. https://pmc.ncbi.nlm.nih.gov/articles/PMC8839325/
6. https://pmc.ncbi.nlm.nih.gov/articles/PMC5783752/#S8
7. https://pmc.ncbi.nlm.nih.gov/articles/PMC10509423/#sec3
8. https://www.sciencedirect.com/science/article/pii/S2666149723000063
9. https://www.nejm.org/doi/full/10.1056/nejmra1905136
10. https://pmc.ncbi.nlm.nih.gov/articles/PMC8470960/
11. https://www.mdpi.com/2072-6643/13/9/3166?gclid=CjwKCAiAmJGgBhAZEiwA1JZolkoEtUSHFEIIb1YencPSKgmVf6Ibs0kyeuA54T-DvRpfmrYBc-aGIBoCwqMQAvD_BwE
12. https://pmc.ncbi.nlm.nih.gov/articles/PMC4697050/
13. https://pmc.ncbi.nlm.nih.gov/articles/PMC7699472/
14. https://www.frontiersin.org/journals/molecular-neuroscience/articles/10.3389/fnmol.2021.732120/full
15. https://pmc.ncbi.nlm.nih.gov/articles/PMC8932957/
16. https://www.sciencedirect.com/science/article/abs/pii/S1568163724000928
17. https://acsjournals.onlinelibrary.wiley.com/doi/full/10.3322/caac.21694
18. https://pmc.ncbi.nlm.nih.gov/articles/PMC4992682/
19. https://pmc.ncbi.nlm.nih.gov/articles/PMC7732631/
20. https://pmc.ncbi.nlm.nih.gov/articles/PMC5371748/
21. https://www.sciencedirect.com/science/article/pii/S0002916523071939?via%3Dihub
