If you’ve been paying attention to diet trends, you’ve probably noticed that intermittent fasting is back in the mainstream. This isn’t so much a straight, strict diet as it is an eating pattern – essentially, with intermittent fasting, you limit how many calories you eat during specific days or hours, cycling between fasting (not eating) and non-fasting (eating) periods.
With claims that intermittent fasting can encourage weight loss to living a longer life, more and more people are trying it! We talked to Dr. Luiza Petre, a cardiologist and weight management specialist, to find out more about this fascinating diet. Below, you'll find everything you need to know about intermittent fasting, including how to do it, some recipe ideas, and how it can benefit you.
What is intermittent fasting?
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Intermittent fasting is an approach to eating in which you don't eat for a designated period of time. This could mean you fast (don't eat) for a certain amount of hours per day, or fast for a couple days a week. There are many intermittent fasting schedules you can adopt, such as the popular 5:2 fasting (eating normally 5 days a week, fasting for 2 days) or daily time-restricted fasting (eating normally only within an 8-hour period per day).
Dr. Petre primarily recommends the 16:8 schedule (eating as you normally would for 16 hours a day, fasting for 8 hours) since it's more sustainable:
“My favorite and easiest time ratio to implement is the 16:8,” she shares. “Out of the 16 hours, you only have to fast for approximately eight hours, because you’re asleep for the other eight. It’s sustainable and easy to maintain. Also, I find it more physiologically sound, as our body has its own clock (called the circadian rhythm), and our hormone levels process food easier during the day.”
How does intermittent fasting work?
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When you fast, your body starts to burn fat for energy instead of burning glucose. Fasting also makes your body more sensitive to insulin, which is a good thing, so you end up with more stable blood sugar levels. This combination helps you lose weight over time. But fasting for long periods of time is not easy or practical in most cases, and that’s why intermittent fasting has become an attractive alternative — days of eating very little are balanced with days of eating normally, you don’t constantly feel hungry and deprived, and you’re more likely to stay on it.
What are the benefits of intermittent fasting?
According to a range of studies, intermittent fasting can encourage expedited weight loss, a longer lifespan, increased insulin resistance, and lowered blood sugar. Additionally, the cumulative affects of intermittent fasting can potentially help prevent heart disease, cancer, and type 2 diabetes.
Are there any risks to intermittent fasting?
If executed poorly, intermittent fasting can lead to malnutrition, which means your body isn't getting all the nutrients it needs to function healthily. Malnutrition could be a result of intermittent fasting only if you're following a stricter schedule and/or not eating an adequate amount of calories per day.
Hunger is the most obvious side effect of intermittent fasting. Lethargy, brain fog, and physical weakness are also common at the beginning.
The good news is that most people don’t experience significant side effects from intermittent fasting as long as they're eating a healthy diet. Dr. Petre points out that you may have to deal with cravings, low energy, and hunger at first, but as your body gets used to intermittent fasting, these problems tend to disappear as your body adjusts over time.
Does intermittent fasting work?
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If you’re looking for a different diet plan that can fit around your schedule, you may want to try intermittent fasting. Dr. Petre admits she was her own guinea pig, trying the intermittent fasting diet on herself first.
After she loved the results, she started to recommend it to her patients. “We have many patients who have lost 40 pounds and more in a 4-5 month time frame.” But intermittent fasting isn’t a quick-fix diet; it’s a lifelong commitment. Dr. Petre recommends thinking of it as a permanent lifestyle change, and you can do it as long as you like.
This eating strategy tends to work because, according to Dr. Petre, “First, there’s no regret, guilt, or real deprivation on this diet. People rebound and feel frustrated when restricted all the time, but with intermittent fasting, that isn’t an issue. It’s also flexible enough that it could be overlapped with another diet such as ketogenic, vegetarian, or Mediterranean. Finally, it’s sustainable! People can stick with it.”
What foods to avoid while intermittent fasting?
Since the fasting period of intermittent fasting requires zero-calorie foods and drinks only, you should avoid foods that have a high calorie content while fasting.
Theoretically, there aren't any foods that are "off-limits" when it comes to intermittent fasting. You can eat whatever you'd like to during the non-fasting period according to the guidelines of the diet. But, if weight loss if your goal, you might consider a low-calorie meal plan full of whole foods to follow for the non-fasting parts of your intermittent fasting journey. If this is the case, consider avoiding candy, soda, chips, fast food, and the like.
On the other hand, we're all human here, and so-called junk foods will inevitably come up with planned date nights, spontaneous movie theater visits, and friends' parties. So, as long as you're enjoying treats (like buttery popcorn or a slice of birthday cake) in moderation, you're still on-track with intermittent fasting!
Can you lose weight eating whatever you want during intermittent fasting?
The intermittent fasting diet doesn't really tell you to avoid specific foods. Instead, its focus is on limiting calories during certain hours or days of the week. Of course, this isn’t exactly an open invitation to indulge in junk food during your non-fasting hours.
Dr. Petre recommends choosing nutrient-dense, unprocessed, fresh, and whole foods. “Most of all, I recommend making protein a priority,” she adds. “Protein keeps you satiated, increases mental clarity, stabilizes blood sugar, boosts energy, and supports your bones and muscles, all while helping maintain your weight. This should be your main source of calories.”
Dr. Petre also encourages dieters to eat organic greens and vegetables like kale, spinach, and onions. She recommends eating them raw, steamed, or baked with seasoning. And, you don’t want to forget about healthy fats! However, you should eat carbohydrates sparingly because they can be calorie-dense and cause further cravings. Dr. Petre tries to avoid pasta, bread, cereal, rice, potatoes, and fruit juices.
As always, it's a good idea to check with your own doctor if you have questions about beginning a new diet such as intermittent fasting. Their expert guidance will help you find the right solution based on your needs and goals!
What famous people do intermittent fasting?
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Here are a few famous people that have done intermittent fasting at one point or another or have previously addressed their experience with the diet:
- Kourtney Kardashian
- Chris Pratt
- Jimmy Kimmel
- Jennifer Aniston
- Mark Wahlberg
- Halle Berry
- Vanessa Hudgens
Intermittent Fasting Diet Plan
Image via The 30-Day Alzheimer's Solution by Dean Sherzai, MD, PhD and Ayesha Sherzai, MD for Brit + Co
If you are curious about starting intermittent fasting, or have began your journey already, it's important to maintain a diet full of foods that will nourish and satisfy you. This way, the diet can grow more pleasurable and sustainable as you ease into it. Below, find a few healthy, low-calories recipe + snack ideas that you can implement into your non-fasting periods.
Recipe Ideas
- Grilled Tempeh Satay Wraps
- Almond Butter Fruit Snacks
- Air Fryer Salmon
- Berry-Oat Smoothie
- Creamy Cauliflower Mash
- Apple Pie Chia Pudding
- Roasted Eggplant Dip
- Matcha Yogurt Bark
- Low-Carb Smoked Salmon Deviled Eggs
Snack Ideas
- Veggies + hummus
- Plain Greek yogurt + berries
- Hard-boiled eggs
- Trail mix
- Cottage cheese with salt + pepper
- Seaweed snacks
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This post has been updated with additional reporting by Meredith Holser.
Lead photo by Alexy Almond / PEXELS.
