Note: This post addresses intermittent fasting as a diet, not fasting done for religious or cultural purposes. You should consult with a doctor, nutritionist, or dietician before trying intermittent fasting, or any diet.
A few weeks ago, a group of friends and I were trying to plan a fairly low-key wine and cheese night. As if trying to work around everyone’s schedules isn’t already difficult enough, we found ourselves faced with a new challenge: one of our pals was intermittent fasting and their “eating window” closed right when the rest of us could get together. Sigh.
This type of time constraint probably isn’t unique to my inner circle, as intermittent fasting (IF) is on the rise. Historically done for religious or cultural reasons, fasting has now become a popular way to lose weight because you don’t have to change what you eat, just when you eat. As an added bonus, there are at least six options for restricting food intake — from skipping one meal per day to fasting for a full 24 hours.
Even though celebs like Jennifer Anniston and Hugh Jackman have had success with IF, we wondered: Is intermittent fasting actually good for you? Sure, fasting is said to have various health benefits other than losing weight, such as lowering high blood pressure, reducing oxidative stress, and boosting brain health, but much of the current research has been done on rats or in early clinical trials. Plus, being hyper-focused on your food might trigger disordered thoughts and behaviors like food-related anxiety or guilt, or even orthorexia.
To get the low-down on the latest diet craze, we turned to the experts at OnPoint Nutrition and Philly Dietitian to find out the benefits and risks of IF, and what nutritional alternatives they’d recommend.
Be Well Philly: Why has intermittent fasting been gaining so much popularity recently?
Katelan Sottosanti, nutritionist at OnPoint Nutrition: Since IF doesn’t require any calorie counting or food restriction (other than the timing), I think people like it because it comes off as easy and makes them feel like they are in control of their food, rather than the other way around. Individuals will set their own eating window and make their own food choices within the chosen time frame, making it adaptable to busy schedules or lifestyles.
What are the benefits of IF?
Theresa Shank, founder of and registered dietitian at Philly Dietitian: Many studies show that IF patterns of eating can cause weight loss, improve your metabolism, and protect against disease and cancers. Though, it’s important to note that current scientific evidence for health benefits of intermittent fasting in humans has often been derived from animal studies. A rat may not have the same weight loss percentage as you! With that said, time-restricted fasting such as 16/8 or even 14/10 is a method that individuals can use to help instill boundaries around their eating routine. I think this type of IF can be a helpful behavioral tool for individuals who need help with recalibrating their hunger cues or struggle to curb overeating.
Emily Horstman, lead dietitian at OnPoint Nutrition: The only pro of IF that I’ve identified is that it can make individuals more aware of their eating habits. Someone who begins to hyper-focus on the timing of their meals may then realize where they are either falling short or consuming excess. One area of excess this can really highlight is the late-night eating many adults tend to engage in due to not eating enough during the day. In this way, IF is appealing because it gives people a fast and easy way to assert control over their daily intake; however, it’s not an answer to long-term health, disease management, or weight loss or management.”
Who shouldn’t be intermittent fasting?
All of our experts agree the following individuals should not be intermittent fasting: women who are pregnant or breastfeeding; anyone under the age of 18; those with a history of disordered eating and/or have obsessive thoughts about food and weight loss; and anyone with a medical condition, especially diabetes. IF might also interfere with certain medications.
Should people be wary of IF?
Gal Cohen, registered dietitian at OnPoint Nutrition: Sometimes, IF can lead to disordered eating thinking patterns and behaviors. While some people can try IF and not exhibit any disordered eating once they stop, others may find that they are too restricted and too stressed over what and when they eat. Research has shown that over-restriction can lead to binges, and micro-managing your food intake and your eating window is pretty much working against your body’s ability to tell you when it’s hungry and full. Spoiler alert: we have hormones that do that!
Sottosanti: One of the big cons of IF is that fasting periods can lead to rebound overeating, which is similar to the binge and restrictive behavior of disordered eating. With some of the fasting techniques including a “one meal a day” schedule, fasting can cause fatigue, difficulty concentrating, and decreased alertness, as well as more serious health consequences like dangerous drops in blood sugar levels and disruption of your menstrual cycle. Individuals are also at risk for developing orthorexia, which is a disorder that involves an unhealthy obsession with healthy eating and constantly thinking about/worrying over your next meal (something fasting for 16 hours could bring on!).
What nutrition habits or practices do you recommend?
Shank: Data across the board highlights the potential importance of synchronizing intermittent fasting regimens with daily circadian rhythms (sleep-wake cycle) to maintain optimal metabolic function. Personally, I encourage clients to be mindful of the timing at which they eat to suffice hunger and their nourishment versus eating as a reaction to stress, boredom, or other emotional or social reasons.
Cohen: The safest eating habit is one that is sustainable! Often, I see clients try to cut out whole food groups, jump on the latest fad diet bandwagon, or follow what’s worked for their friends, only to realize that approach isn’t working for their body. My advice: If it’s not something you can see yourself doing long-term, it’s not for you.
Sottosanti: Eating balanced meals about 3-4 hours apart encourages the intake of more nutrients throughout the day, cutting down on the chances of overindulgence at meal time. I [and the OnPoint team] advocate for a whole-foods, anti-diet approach to healthy eating that is sustainable over time. That’s when your nutritional habits truly reflect a beneficial, healthy lifestyle, rather than a bandwagon diet.