16:8 Fasting For Beginners: Pros, Cons, & Sample Meal Plans

Fasting is an ancient practice that’s been used for spiritual and religious purposes for thousands of years. Nowadays, it's the physical benefits of fasting—from blood sugar balance to enhanced energy—that are the buzziest.

There are different types of fasting, but 16:8 is one of the most popular and well-studied. Not only has 16:8 fasting been shown to be effective for improving multiple health outcomes, but it’s less restrictive and easier to follow than other methods (looking at you, 5:2). 

16:8 is one of the most popular types of intermittent fasting (IF)—an umbrella term that includes eating patterns that involve regularly occurring periods of fasting that are longer than a normal overnight fast1.

16:8 is considered time‐restricted eating (TRE), which is one of the major forms of IF. In TRE, calorie intake is restricted to a specific time period2. TRE involves eating as much or as often as you like within a defined period of time, usually between 3 and 12 hours per day, which results in a fasting window of 12 to 21 hours per day. 

Using the 16:8 method, you consume all of your calories within an 8-hour window and fast for 16 hours.

“We normally have a daily overnight fast that lasts from 8 to 12 hours and is broken by the 'break-fast' in the morning, so the body is used to daily fasting for some length of time,” explains Kyrin Dunston, MD, FACOG. Engaging in 16:8 fasting prolongs this daily fast to 16 hours.

When you limit your eating to a set time period, it usually results in a reduced calorie intake5. This calorie deficit can then promote weight loss.

A 2023 meta-analysis published in Food Science & Nutrition that included eight studies found that the participants who followed 16:8 fasting experienced significant weight loss and fat mass reduction2 compared to control groups.

16:8 fasting can be used with any type of diet, such as low-carb diets and high-protein diets, both of which are effective for promoting weight loss on their own. But, combining a weight loss-promoting diet with 16:8 may be more effective than dieting alone.

A 2022 study that included 169 people found that 16:8 fasting paired with a low-carb diet led to a greater reduction in body weight6 than a low-carb diet or 16:8 fasting alone over a 3-month period. Additionally, only the combination treatment was effective for reducing body weight at month three compared with month two.

Research suggests that engaging in IF could be a simple way to improve blood sugar control in people with diabetes. 

A 2023 review published in Nutrients concluded that people with type 1 and type 2 diabetes can safely use fasting protocols like 16:8 to improve glycemic control7, reduce body weight, and improve insulin sensitivity. 

In addition to benefiting blood sugar control and insulin sensitivity (both of which are essential for a healthy heart), 16:8 fasting may improve heart disease risk factors8 like high levels of blood pressure, LDL cholesterol, and triglycerides.

A 2020 review of 19 studies published in Nutrients found that intermittent fasting protocols, including 16:8 fasting, led to significant reductions in blood pressure9, blood sugar, and triglyceride levels. Other studies have shown that 16:8 fasting can also improve LDL and total cholesterol levels10.

Using the 16:8 method may also support overall health by reducing systemic inflammation and stimulating autophagy—a cellular cleansing process by which your cells break down and destroy old, damaged, or abnormal substances. This cellular waste is then used for energy or to make new cellular components.

Because the process of autophagy preserves cellular health11, using practices that trigger autophagy, such as IF, may help support a longer and healthier life. 

There’s a reason why many healthcare providers recommend the 16:8 method for weight loss.

A 2020 review that included 27 studies found that fasting regimens, including 16:8 fasting protocols, that lasted for 2 to 26 weeks resulted in weight loss ranging from 0.8% to 13.0% of baseline weight. 

A 2023 review of 43 studies showed that people who engaged in IF regimens like 16:8 experienced greater reductions in waist circumference13, body weight, and fat mass compared to other diets, including reduced-calorie diets. The IF regimens were also more effective for maintaining lean body mass compared to the other diets.

Fasting is especially beneficial for promoting belly fat loss, including the loss of visceral fat, a type of deep belly fat linked to increased disease risk. In a 2020 study, adults considered overweight who were randomized to eat within an eight-hour period for 12 weeks experienced an 11.1% average reduction in their visceral fat levels14 compared to their baseline levels. 

While more restrictive types of fasting, such as alternate-day fasting (ADF), can also support weight loss, 16:8 is much easier to stick to long-term.

“While more extreme fasting programs can lead to additional weight loss in the short term, they don't typically help establish long-term habits in the same way a more balanced, conservative program can,” Grant Tinsley, PHD, a professor at Texas Tech University and intermittent fasting researcher, previously told mindbodygreen.

One thing to consider if you're looking to use fasting to lose fat is that you'll likely lose muscle in the process too. Muscle mass can negatively impact strength and metabolism15, and having more muscle mass increases the number of calories you burn while at rest. So it's important to continue to build (or at least maintain) your muscle mass through resistance training and a higher-protein diet while fasting. Prioritizing healthy, nutrient-dense foods within your eating window is also key.

There’s a decent amount of research supporting the safe use of 16:8 and other TRF fasting methods in women. Many studies have shown that 16:8 can be effective for promoting weight loss, improving blood sugar levels, and supporting other aspects of health18 in women of all ages. 

That said, there are a few factors specific to women’s health to consider. For example, unless it’s being used to treat a specific health issue, fasting is generally not advised during pregnancy and breastfeeding. Also, it’s not an appropriate practice for women with eating disorders, like anorexia or bulimia.

Some research also suggests that fasting may not be the best choice for some women over the age of 50, as prolonged fasting periods may negatively impact hormone levels, increase menopausal symptoms like hot flashes19, and worsen balance and lower extremity function. However, there is other research to show that fasting can actually relieve some of the side effects of menopause, so it depends on the person.

Some women may also want to take a break from fasting during the luteal phase of their period, when they tend to be more vulnerable to stress.

Sara Gottfried, MD, a board-certified physician who specializes in women’s health and integrative medicine, explains that intermittent fasting can be especially effective for women with polycystic ovary syndrome (PCOS), a hormonal disorder characterized by cystic ovaries, irregular periods, and excess androgen levels.

A 2021 study20 published in The Journal of Translational Medicine found that women with PCOS who followed a 16:8 fasting regimen for six weeks experienced significant improvements in body weight, insulin resistance, menstrual cycle irregularity, and testosterone levels.

One of the benefits of 16:8 is that it’s flexible and can be designed to suit your schedule. You can choose when you’d like to schedule your feeding window in the morning or evening.

People who have busier mornings or who like to work out earlier in the day may prefer to schedule their eating window closer to their morning workouts or their start of work, while people who are busier later in the day or who prefer to skip breakfast may benefit from a later eating schedule.

No matter your eating regimen, it’s important to fuel your body with nutritious foods. Though there are no food rules associated with 16:8 fasting, it’s best to choose whole, nutrient-dense foods whenever possible. 

Though 16:8 fasting has been linked with several health benefits, not everyone's a fan of the practice. Some people may not like going for extended periods of time with no energy intake or have physically demanding jobs that require a steady supply of calories throughout the day, for example.

As long as it’s done in a healthy way, intermittent fasting is considered safe and isn’t associated with many adverse side effects. Keep in mind that 16:8 fasting is considered one of the least restrictive fasting types, as it only involves an 8-hour fast. 

Longer fasts, such as fasting regimens that involve fasting for 24 hours, are more likely to cause side effects24 like extreme hunger, headaches, irritability, nausea, fatigue, and lightheadedness. However, people who are sensitive to calorie restriction may also experience these side effects when engaging in shorter fasts, such as 16:8 fasts.

If you're interested in time-restricted eating, the 16:8 fasting plan is a solid place to start. It's less restrictive than other plans but still has research backing up its benefits for metabolic function and cardiovascular health. 16:8 fasts usually lead to caloric restrictions, and weight loss by extension. To ensure you're not losing too much muscle along with fat, aim to do resistance training and eat plenty of protein on this plan.