What Is 16/8 Intermittent Fasting? A Beginner’s Guide

The practice of 16/8 intermittent fasting involves limiting your intake of foods and calorie-containing beverages to a set window of 8 hours per day. You abstain from food for the remaining 16 hours, though you’re still allowed to drink water and other no-calorie beverages, like plain coffee or tea.

You can repeat this cycle as frequently as you’d like — from just once or twice per week to every day, depending on your preference.

The popularity of this fasting method has grown widely among those looking to lose weight and burn fat. 16/8 intermittent fasting is also believed to improve blood sugar control and enhance longevity (1).

While other diets often set strict rules, 16/8 intermittent fasting is simple to follow and may provide measurable results with minimal disruption to your diet. It’s generally considered less restrictive and more flexible than many other diets and works with most lifestyles.

Summary

With 16/8 intermittent fasting, you restrict your food intake to an 8-hour window and fast for the remaining 16 hours. This practice may support weight loss, improve blood sugar, and increase longevity.

This is what you need to know to do 16/8 intermittent fasting.

Choosing a time window

To get started, begin by picking an 8-hour window and limiting your food intake to that time span.

Popular 16/8 time windows include:

• 7 a.m. to 3 p.m.
• 9 a.m. to 5 p.m.
• 12 p.m. to 8 p.m.
• 2 p.m. to 10 p.m.

Many people prefer to eat between noon and 8 p.m., since you need to fast only overnight and skip breakfast but can still eat a balanced lunch and dinner, along with a few snacks throughout the day.

Others opt to eat between 9 a.m. and 5 p.m., which allows plenty of time for a healthy breakfast around 9 a.m., a standard lunch around noon, and a light, early dinner or large snack around 4:30 p.m. before starting your fast.

However, you can experiment and pick the time frame that best fits your schedule.

It may help to set timers at both the beginning and the end of your eating window to remind you when to start and stop eating.

Foods list and meal plan

To maximize the potential health benefits of your diet, it’s important to stick to nutritious whole foods and beverages during your eating periods.

Filling up on nutrient-rich foods helps round out your diet and supports a healthy weight. Try balancing each meal with a wide variety of whole foods, such as:

• Fruits: apples, bananas, berries, oranges, peaches, pears, tomatoes, etc.
• Veggies: broccoli, Brussels sprouts, cauliflower, cucumbers, leafy greens, etc.
• Whole grains: barley, buckwheat, quinoa, rice, oats, etc.
• Healthy fats: olive oil and avocados
• Protein sources: eggs, fish, legumes, meat, poultry, nuts, seeds, etc.

Drinking calorie-free beverages like water and unsweetened tea and coffee, even while fasting, also helps control your appetite while keeping you hydrated.

It’s best to limit ultra-processed foods like packaged snacks, deep-fried items, sugary drinks, and most frozen meals. These negate the positive effects of 16/8 intermittent fasting.

Summary

To begin 16/8 intermittent fasting, choose an 8-hour window and limit your food intake to that time span. Be sure to follow a balanced diet based in whole foods.

One of the main advantages of 16/8 intermittent fasting is its convenience. It can cut down on the time and money you need to spend on cooking and preparing food each week.

It has been associated with a long list of health benefits.

Increased weight loss

Restricting your eating window to a few hours per day can cut your calorie intake over the course of the day, which in turn may contribute to weight loss.

In fact, research reveals that fasting may boost weight loss.

For example, one review found that 11 of 13 studies on intermittent fasting reported statistically significant weight loss in participants (2, 3).

Improved blood sugar control

Intermittent fasting has been shown to reduce fasting insulin and blood sugar levels, potentially decreasing your risk of diabetes (4, 5).

Extended longevity

Evidence in humans is limited, but some animal studies note that intermittent fasting may extend longevity.

It’s thought that fasting affects metabolic pathways, improves insulin sensitivity, and leads to behavioral changes that together may lengthen your life span. However, these mechanisms aren’t fully understood (6, 7).

Summary

Animal and human studies suggest that intermittent fasting may increase weight loss, improve blood sugar levels, and extend longevity.

Although 16/8 intermittent fasting is associated with several health benefits, it has a few side effects and may not be right for everyone.

Be sure to start your fasting regimen gradually and consider stopping or consulting your doctor if you have any concerns or experience negative symptoms.

Overeating and potential weight gain

Restricting your intake to just 8 hours per day may cause some people to eat more than usual during eating periods in an attempt to make up for hours spent fasting. This may lead to weight gain, digestive problems, and unhealthy eating habits.

Interestingly, current research doesn’t suggest that intermittent fasting leads to any more weight loss than typical diets that recommend overall calorie restriction. Both eating patterns may lead to modest weight loss (3, 8).

If weight loss is your primary goal, you may therefore prefer to lower your calorie intake, exercise more, eat more whole foods, or sleep sufficiently instead of fasting intermittently to prevent the overeating that may occur when restricting intake to a certain time window.

In addition, weight loss may occur while fasting, but when returning to normal eating patterns, it’s common to regain the weight.

Short-term physical symptoms

The practice of 16/8 intermittent fasting may cause short-term negative side effects when you’re first getting started, such as hunger, weakness, and fatigue — though these often subside once you get into a routine.

Hormonal changes and menstrual cycles

Some animal research suggests that intermittent fasting may lead to hormonal changes and undereating. In people with ovaries, these changes may negatively affect menstrual cycles and fertility (9, 10).

However, most studies are old and have been conducted in animals. Human studies are needed to fully understand how intermittent fasting may affect reproductive health.

Furthermore, postmenopausal individuals may experience different effects from intermittent fasting. Menopause causes changes that can decrease insulin sensitivity and lead to weight gain, and intermittent fasting may help improve these outcomes (11).

Summary

Restricting daily food intake to a particular time window may cause increased food intake and weight gain, as well as short-term hunger and weakness. Older animal studies indicate that intermittent fasting may interfere with fertility.

It’s true that 16/8 intermittent fasting can be a sustainable, safe, and easy way to improve your health when paired with a nutritious diet and healthy lifestyle.

However, it shouldn’t be viewed as a substitute for a balanced diet rich in whole foods. Plus, you can still be perfectly healthy if you don’t follow intermittent fasting.

Though 16/8 intermittent fasting is generally considered safe for healthy adults, you should talk with your doctor if you have any underlying health conditions. This is key if you’re taking any medications or have diabetes, low blood pressure, or a history of disordered eating.

Intermittent fasting is likewise discouraged if you’re trying to conceive, pregnant, or nursing.

If you have any concerns or experience any side effects while fasting, be sure to consult your doctor.

The practice of 16/8 intermittent fasting involves eating only during an 8-hour daily window and fasting for the remaining 16 hours.

It may boost weight loss, blood sugar control, and longevity.

Still, it’s vital to follow a healthy diet during your eating period and drink calorie-free beverages like water or unsweetened teas and coffee during your fasting period.

It’s best to talk with your doctor before trying intermittent fasting, especially if you have any underlying health conditions.