It feels like there are as many weight loss plans out there as new fashion trends popping up on your Instagram feed, so it can be difficult to figure out which healthy eating style might be right for you.
One approach, intermittent fasting (IF), requires you to eat and fast during specific time windows. While some types of IF have windows that can be more restrictive—sometimes calling for skipping an entire day of eating or consuming all of your meals in a few hours—16:8 intermittent fasting is generally more liberal and flexible, since you fast for 16 hours and eat for eight hours.
Meet the experts: Alissa Palladino, RDN, CPT, is a registered dietitian nutritionist and certified personal trainer based in Atlanta, Georgia. Lisa Moskovitz, RD, CDN, is a registered dietitian and the CEO of NY Nutrition Group.
The idea behind IF is that it can instill structure to your eating, which may help reduce unnecessary snacking and allow you to consume more nutrient-dense foods when you do eat, potentially leading to weight loss, says registered dietitian nutritionist and certified personal trainer Alissa Palladino, RDN, CPT.
Ahead, discover the benefits and potential drawbacks of 16:8 fasting, and find out how to safely try it, if it’s right for you.
How To Safely Try 16:8 Fasting
Since this plan gives you an eight-hour window to eat, you’ll need to figure out the best stretch of time to eat so you can consume the right amount of nutrient-dense calories for the day. Palladino recommends eating between 10 a.m. and 6 p.m. since it generally works with people’s daily schedules, between work, childcare, and workouts.
Speaking of workouts, if you exercise before work or afterward, make sure your eating window allows you to fuel before and after. Before your workout, consume some simple carbs like a banana or oatmeal, and within an hour after your workout, refuel with a full meal that includes carbs, protein, and fat, Palladino says. (BTW, intermittent fasting probably isn’t the best fit for folks training for a performance goal, like running a half-marathon or hitting a new deadlift PR, because they’ll need consistent fueling, regardless of the time of day.)
This extra planning around your workouts can get a bit tricky. For example, if you start your eating window at 7 a.m. ahead of your workout, you’ll have to wrap up eating at 3 p.m., meaning you might miss dinners with friends and family. In that case, you might want to try a more flexible IF approach, like 12:12 (fast for 12 hours, then eat for 12).
What To Eat While 16:8 Fasting
Deciding what to consume during your feeding window is just as important—if not more important—than the eating schedule itself, Palladino says. While everyone’s nutrition needs vary, there are a few simple tactics to ensure you’re properly fueling throughout the eight-hour feeding window.
“A balanced meal should have fiber-rich carbs, protein, some healthy fats, and colorful fruits and vegetables,” Palladino says. To monitor your nutrient intake, she recommends breaking your plate into quarters. Fill a quarter with protein, another quarter with a starchy vegetable (like sweet potatoes) or carb (like quinoa), and then the remaining half with fruits and vegetables. Lastly, use toppings (like a sprinkle of parmesan cheese) for a little healthy fat, she adds.
Reminder: Tweak your nutrition to align with your own body, lifestyle, and schedule. A registered dietitian can help you optimize what you eat if you’re not certain what’s best.
Here’s an example of what to eat with an eating window of 12 p.m. to 8 p.m., according to registered dietitian Lisa Moskovitz, RD, CDN:
12 p.m.: Grilled salmon over a mixed green salad with chickpeas, quinoa, avocado, and an olive oil-based dressing
“This combo of protein, fiber, and fat is packed with nutrients to make up for the missed morning meal,” Moskovitz says.
3 p.m.: Greek yogurt with fresh fruit and mixed nuts
“This is another fiber- and protein-packed snack to ensure proper nutrient intake and feed your muscles while stabilizing blood sugar throughout the day,” Moskovitz says.
6 p.m.: Chicken breast with roasted veggies and a baked potato cooked in extra virgin olive oil or avocado oil
“Filling up on voluminous veggies can naturally keep portions in check while providing plenty of nutritional value,” Moskovitz says. And chicken breast will help you hit your protein goal.
7:30 p.m.: Frozen yogurt bar and dark chocolate
A little treat at the end of the day can help with overall satisfaction and prevent any feelings of deprivation that may occur with a fasting diet,” Moskovitz says.
It’s also always important to stay hydrated, regardless of when and how often you eat throughout the day, says Moskovitz. Try to drink half your weight in ounces of plain fluid water, she says.
If you have an active lifestyle—like you’re exercising daily or biking to your job, working in a physically demanding environment, or racing after young children during the day—or you break a sweat easily, Moskovitz recommends consuming one electrolyte packet during the day. (However, each person’s hydration needs vary, and it’s best to consult with a licensed professional for more customized guidance, she says.) Of course, you’re also encouraged to drink anything without calories or sugar like water, black coffee, or tea, adds Palladino.
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Health Benefits Of 16:8 Fasting
More research on 16:8 intermittent fasting needs to be done, but some studies suggest that the eating style may offer (limited) benefits for certain groups.
It may promote weight loss.
Generally, intermittent fasting has been found to be helpful for weight loss in populations with obesity, per 2020 research in Canadian Family Physician. And 16:8 fasting has similar benefits: A 2023 meta-analysis in the European Journal of Clinical Nutrition confirmed that those who adhered to a 16:8 fasting style significantly reduced their weight.
One of the most effective ways to lose weight is through hitting a calorie deficit each day, or consuming fewer calories than you’re burning. It might be easier for some people to consume fewer calories “if they’re constrained by the hours that they’re eating in the day,” Palladino says, which may be one reason why intermittent fasting may help with weight loss. So, if you have a habit of snacking after dinner, but your time window ends at 7 p.m., you’ll be less inclined to grab those pretzels, in theory, Moskovitz says.
It can potentially help treat type 2 diabetes.
When someone has type 2 diabetes or has prediabetes, their bodies have become resistant to insulin, the hormone responsible for regulating blood sugar, per the Cleveland Clinic. It can occur for a number of reasons including genetics, limited physical activity, hormonal disorders, and poor nutrition, according to the Cleveland Clinic.
Moderating the body’s blood sugar (or glucose) levels while regulating its insulin sensitivity is the key to treating type 2 diabetes. Intermittent fasting can be beneficial at accomplishing this, according to a 2021 meta-analysis in Clinical Diabetes and Endocrinology which found that people who engaged in intermittent fasting improved their insulin levels.
Another study in the Journal of Pharmacy and Bioallied Sciences found that participants with obesity and type 2 diabetes who tried 16:8 intermittent fasting for a month significantly reduced their fasting blood glucose levels and body measurements like BMI and waist circumference.
It may be easier to maintain than more restrictive types of IF.
While some may find it challenging to adjust to the eight-hour feeding window, 16:8 intermittent fasting is more liberal than other approaches to the eating style, Moskovitz and Palladino say. Some of these require fasting for longer hours (like 20:4, where you fast for 20 hours and eat for four) to days (like 5:2, where you fast for two non-consecutive days and eat regularly during the other five days of the week). Because of this flexibility, 16:8 intermittent fasting may be naturally easier to follow, and might be a better option for folks on medications that have to be taken with food, says Moskovitz.
Potential Risks And Drawbacks of 16:8 Fasting
It might cause you to lose muscle.
“Intermittent fasting can contribute to muscle loss,” says Moskovitz. This large fasting window can put the body in a catabolic state, the natural process in which the body breaks down proteins, carbs, and fat for energy. If you’re underfueled, you body will resort to depleting nutrients from other available sources in the body, namely your lean muscle.
When your body is underfueled and tapping into lean muscle for energy, your muscles will be unable to repair effectively, meaning you’ll risk not recovering from workouts as well, adds Palladino.
It can impact your hormones.
Maintaining a healthy hormonal balance is key to your reproductive health, bone health, and weight management, according to 2024 research in Frontiers in Nutrition and the International Osteoporosis Foundation. Unfortunately, fasting may cause your estrogen levels to decline, per a 2024 study in Frontiers in Nutrition. (Although 2022 research in Nutrients and Obesity says fasting has no impact on women’s estrogen.)
Low or declining estrogen levels are linked with female sexual dysfunction, a disruption in your menstrual cycle (which may be associated with infertility), vaginal atrophy (where the lining of your vagina may become thin and dry), and osteoporosis, per the Cleveland Clinic. “Estrogen plays a role in preventing bone cell breakdown,” says Palladino. Without the appropriate estrogen levels, it can’t sustain bone health, lowering bone density commonly seen in menopausal and postmenopausal people, and those with lower estrogen levels, she adds.
Restrictive diets like intermittent fasting can potentially also lead to functional hypothalamic amenorrhea, or the loss of your period without other factors like chronic illness, according to 2021 research in Nutrients.
It may lead to disordered eating habits.
The risk of developing disordered eating after trying intermittent fasting is “substantial,” per 2023 research in Clinical Diabetes and Endocrinology. The research also found that restrictive eating habits and dieting can lead to disordered eating like anorexia and orthorexia. That’s why Palladino doesn’t suggest any type of intermittent fasting to those with a history of disordered eating.
Plus, 16:8 intermittent fasting can lead to poor eating habits. If you get super hungry in your fasting window, you might overeat or binge eat unhealthy foods impulsively when you do eat, Palladino says. In the long-term, that won’t help with weight loss or improving health.
It can be difficult to maintain long-term.
Eating in an eight-hour time window can make it hard to just live your life—including grabbing breakfast with your friends at 9:30 a.m. or dinner with your S.O. at 7 p.m.
“I’m always encouraging people to find a way of eating that will promote their health goals in the short-term and the long-term,” Palladino says. It might be more beneficial to instead follow the plate rule she suggested (a quarter of it is protein, another quarter is a starchy veggie or carb, and the remaining half is fruits and veggies) to help you feel satiated while eating a yummy, nutritious meal.
Who Should (And Shouldn’t) Try 16:8 Fasting
It may be helpful for those who are obese and have a weight loss goal, at least in the short run, Palladino and Moskovitz say. (There are currently no long-term studies on the efficacy of 16:8 intermittent fasting—most research has been conducted over a four-week to six-month period.)
However, Palladino doesn’t ever recommend 16:8 intermittent fasting because of its limited feeding window, possible negative impacts to hormone and bone health, and vulnerability to developing disordered eating.
Palladino and Moskovitz say the following groups should especially stay away from 16:8:
- Female athletes because they require consistent fueling throughout the day to ensure their bodies are primed for workouts and nourished for optimal recovery, says Palladino.
- Women in their reproductive years because there could be a possible negative impact on their hormonal balance, which can have ongoing effects on ovulation and menstruation, says Moskovitz.
- Pregnant and breastfeeding people because they need more nutrients, and restricting the hours they can eat would likely prevent them from consuming enough food for both the mother and growing baby, says Palladino.
All in all, 16:8 intermittent fasting might be appropriate for a small, specific group of people who are interested in weight loss. If you fall outside these groups and still want to lose weight, you may benefit from working with a registered dietician or other licensed medical provider to help you come up with an eating style that best fits your lifestyle and health needs.
Liz Doupnik is a freelance culture and lifestyle journalist based in Nashville, TN who writes about books, fashion, and wellness. With nearly 20 years of experience, Liz cut her teeth working as a full-time editor at WWD, StyleCaster, and Seventeen, and has led editorial teams at SHAPE and Nike. A lifelong athlete, Liz has also worked as a certified personal trainer and obtained her Master Training certification from Focus Personal Training Institute. As a freelancer, her work has appeared in W, Marie Claire, Dwell, Teen Vogue, Well & Good, The Zoe Report, and many others. When she’s not busy at work, you can find her logging a long run on one of Nashville’s many trails, perusing the shelves at her favorite local bookstore, or searching for her future rescue pup.
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