16/8 Intermittent Fasting: Meal Plan, Benefits And Side Effects (2024)

The 16/8 intermittent fasting approach is a form of time-restricted eating, which involves limiting your food intake to an eight-hour window during the day and fasting for the remaining 16 hours. This type of fasting is believed to offer health benefits by flipping a metabolic switch, causing your body to exhaust its sugar stores and begin burning fat. In addition to potentially supporting weight loss, it’s also purported to help reduce chronic inflammation and protect against certain health conditions.

While being easy to follow, the 16/8 fasting is considered one of the most popular approaches to intermittent fasting and allows you to select any eight-hour block of window based on your schedule and preferences. For example, you might choose to have a light breakfast at 10 a.m., eat lunch at 12 p.m. and have an early dinner at 5:30 p.m. and then fast overnight. Alternatively, you may prefer skipping breakfast altogether and limiting your eating window to 12 p.m.-8 p.m. each day. The American Academy of Family Physicians notes that while any block of time can work, it’s important to stick to the same schedule each day.

Some research shows limiting your food intake to an eight-hour window might offer several health perks. Here are a few of the top expert-backed benefits of 16/8 intermittent fasting.

May Promote Weight Loss

“During the fasting window, you consume little to no calories,” explains Sam Schleiger, a functional medicine dietitian and owner of Simply Nourished Nutrition, a private practice in Elkhorn, Wisconsin.“This can create a calorie deficit, which is necessary for weight loss. If you consistently consume fewer calories than you burn, you are more likely to lose weight.”

Some people might also find that practicing intermittent fasting can help them better control their appetite, she adds. “During fasting periods, your body may [also] tap into its fat stores for energy, potentially increasing fat burning,” Schleiger says. However, she also notes that results can vary depending on many factors including your sex, genetics, metabolism and overall diet quality.

One small study that focused on older adults (aged 65-74 years) found that restricting food intake to eight hours per day for six weeks resulted in an average weight loss of 4 pounds for men and 2.9 pounds for women. Men also experienced a significant reduction in visceral fat mass and belly fat during the study, though there was no significant effect on fat mass for women^[1]Domaszewski P, et al. Comparison of the Effects of Six-Week Time-Restricted Eating on Weight Loss, Body Composition, and Visceral Fat in Overweight Older Men and Women. Exp Gerontol. 2023;174:112116. . Another small study showed that both alternate-day fasting and 16/8 intermittent fasting were effective for weight loss in adults with prediabetes and overweight or obesity. However, alternate-day fasting (a type of intermittent fasting that involves fasting for 24 hours, then eating for the next 24 hours, then fasting again for the following 24 hours, etc.) led to greater reductions in body weight and body mass index (BMI) during the three-week study^[2]Chair SY, et al. Intermittent Fasting in Weight Loss and Cardiometabolic Risk Reduction: A Randomized Controlled Trial. J Nurs Res. 2022;30(1):e185. .

Might Extend Longevity

It’s possible that intermittent fasting may increase lifespan through a variety of mechanisms, explains Robert Iafelice, a registered dietitian based in Mentor, Ohio and nutrition expert at Set for Set, an online fitness resource. Intermittent fasting can extend longevity by enhancing the body’s response to stress, according to Iafelice, who notes that fasting also activates certain pathways in the body that help protect cells against damage and promote cell repair and survival.

According to one review, intermittent fasting may also help reduce risk factors for conditions like diabetes, heart disease, neurodegenerative disorders and cancer, which could result in increased longevity^[3]Longo VD, et al. Intermittent and Periodic Fasting, Longevity and Disease. Nat Aging. 2021;1(1):47–59. . Other research suggests that intermittent fasting may help extend lifespan by protecting against oxidative stress, improving cognition and altering specific pathways in the body to trigger cell repair^[4]Wilhelmi de Toledo F, et al. Unravelling the Health Effects of Fasting: A Long Road From Obesity Treatment to Healthy Life Span Increase and Improved Cognition. Ann Med. 2020;52(5):147-161. .

Can Support Blood Sugar Control

Intermittent fasting can enhance insulin sensitivity, which improves the body’s ability to use insulin, explains Schleiger. She notes that this makes your cells more responsive to insulin, thereby regulating blood sugar levels more efficiently. “By limiting the times during which you eat, intermittent fasting can [also] help stabilize blood sugar levels throughout the day,” Schleiger continues. “This can reduce the spikes and crashes in blood sugar that can occur with frequent eating.”

Indeed, a small 2021 study in 120 people with type 2 diabetes found that time-restricted eating improved blood sugar levels, enhanced insulin sensitivity, increased weight loss and reduced the dosage required for diabetes medications^[5]Che T, et al. Time-Restricted Feeding Improves Blood Glucose and Insulin Sensitivity in Overweight Patients With Type 2 Diabetes: A Randomised Controlled Trial. Nutr Metab (Lond). 2021;18:88. . What’s more, another review of five studies concluded that early time-restricted eating (or restricting food intake to early in the day) did seem to improve blood sugar control, especially in individuals with a normal BMI^[6]Bitsanis D, et al. The Effect of Early Time-Restricted Feeding on Glycemic Profile in Adults: A Systematic Review of Interventional Studies. Rev Diabet Stud. 2022;18(1):10-19. .

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Though 16/8 intermittent fasting might offer some health benefits, there are potential drawbacks to consider. Some people may experience increased hunger, irritability and discomfort while fasting, notes Schleiger, which can make it more difficult to stick to, especially when you’re first getting started. In fact, Johns Hopkins Medicine states that it may take up to two to four weeks for the body to fully adjust to intermittent fasting.

Intermittent fasting can also make it more challenging to get the essential vitamins and minerals that your body needs, says Schleiger, who emphasizes the importance of following a balanced diet to prevent nutritional deficiencies. For instance, those who don’t regularly get their veggies while eating a “regular diet,” will find it more difficult to do so when following this intermittent fasting approach. Vitamin-mineral supplementation may need to be considered to help meet essential needs.

Additionally, intermittent fasting is not recommended for certain groups, including:

• Children and teens under 18
• Individuals with a history of eating disorders
• People with type 1 diabetes who take insulin, or those with type 2 diabetes who take medication and require a strict meal plan
• Those who are pregnant or breastfeeding, or trying to get pregnant
• Athletes or other individuals with high performance needs

Be sure to check in with your doctor before trying intermittent fasting or making other changes to your diet, especially if you have any underlying health conditions.

While you’re fasting, water and zero-calorie beverages, such as black coffee or tea, are permitted and encouraged for proper hydration—and can be consumed at any time. Meanwhile, during your eating window, it’s recommended to enjoy a variety of nutritious foods, such as leafy greens, lean proteins, whole grains and heart-healthy fats.

Here is what a basic 16/8 intermittent fasting, seven-day meal plan might look like, according to Susan Juechter, a senior dietitian at Phelps Hospital of Northwell Health in Westchester, New York. Note: People with high energy needs will want to try to include the optional snacks.

While it’s not an ideal fit for everyone, 16/8 intermittent fasting can be a flexible, easy-to-follow eating pattern that may offer several benefits. If it’s a good fit for you, be mindful to pair 16/8 with a nutritious, well-rounded diet to ensure you’re getting the nutrients you need, and talk to a doctor before trying it, especially if you have any underlying health conditions.