16:8 Intermittent Fasting | Benefits & How to Do It Properly

Intermittent fasting has become a popular topic both for researchers and health
enthusiasts. It, like the 16:8 diet, promises weight loss, better performance,
increased fat burning and lean muscle preservation. While there are several
different types of intermittent fasting, such as the 5:2 diet or religious-based
fasting, 16:8 is a sustainable pattern that’s associated with lean muscle
gains.1 This article explores the potential benefits and the best way
to determine if the 16:8 plan is right for you.

In This Article, You’ll Find:

people eating healthy food

What is Intermittent Fasting?

By definition, this means eating for a certain period of hours and then fasting
(not eating) for a set number of hours. The theory behind intermittent fasting
(IF) is that humans did not used to live in environments where we had access to
food 24 hours a day like we do now — rather, our ancestors evolved in a time
when food was relatively scarce, and they had to function at their best
physically and mentally often in a fasted state.2

In modern times, this translates to not eating for many hours in a day, working
out in a fasted state, and then limiting your meals during the day to a shorter
number of hours than your fast. The 16:8 intermittent fasting diet is one
example of this.

What is the 16:8 Diet?

The 16:8 intermittent fasting diet limits eating to 8 hours a day and requires
fasting for the remaining 16 of 24 hours. Although 16 hours seems like a long
time, this includes time spent sleeping. The theory is to wake and work out in a
fasted state, which forces your body to draw upon fat stores for energy.2

You should consume reasonable meals throughout your 8 eating hours. While
fasting, you should drink water, and some choose to include unsweetened tea,
coffee, or
in the mornings before exercise.

What are the Benefits of Intermittent Fasting?

It is a popular topic in research and there have been some animal studies
showing beneficial impacts on weight loss and cardio-metabolic risk factors
(like blood pressure, cholesterol, and insulin-resistance).3 Some
studies show a greater benefit from intermittent fasting than from a continuous
calorie restriction style diet.4

Additional experimental models predict potential positive impacts of
intermittent fasting to extend to age-related disorders, although more research
in these areas is needed.2

There have been studies showing that performance does not suffer in a fasted
state, and some intermittent fasting dieters claim that they have even more
energy and mental clarity when following a 16:8 style diet.5 There’s
less mental effort and stress dedicated to meal planning and prepping. Following
a 16:8 diet is sometimes referred to as “lean gains”, building on theory of
burning fat and calories while working out in a fasted state.1 This
method of fasting has been shown to be effective in limiting calorie intake to
reduce fat while still maintaining performance and muscle tissue.1

Practical benefits of intermittent fasting include less time spent preparing,
eating, and cleaning up after meals (versus a diet of six small meals a day, for
example), and its flexibility. You may only need to plan for two meals and they
can be larger portions. The major guidelines for the 16:8 diet rely on the
timing of meals and not exactly which foods you need to eat. Intermittent
fasting doesn’t require calorie- or macro tracking, but can be used in
conjunction with any healthy diet pattern you already follow. For those who
struggle with mindless snacking throughout the day or boredom eating at night,
having a strict eating schedule can prevent those unnecessary calories that can
lead to weight gain.

breakfast porridge bowl

How to Intermittent Fast Safely

To follow the 16:8 intermittent fasting plan safely, you need to make sure to
stay well hydrated while not eating by drinking plenty of water. Coffee or
unsweetened green tea may be consumed in the morning to help fuel your workout
(or you can use Pre-Workout), as long as you are not adding any cream or
sweeteners. There is some thought that consuming aBCAA supplement right before
your fasted workout can help to prevent muscle loss.1

When you’re in the 8-hour eating period, it’s crucial to obtain high quality
meals containing all of your necessary macros (protein, carbs and fat) and
vitamins/minerals for the day. Be sure to stay hydrated and meet your protein
needs to prevent anylean muscle
loss. It may be more difficult to obtain adequate calories in a short period of
time, which may lead to weakness or dizziness.3

Additionally, be cautious of not overeating just because you know you have
another 16-hour fasting period ahead. Intermittent fasting is designed to keep
your body in deficit for the day as a whole, so be cautious not to binge on
high-calorie junk foods.6

While there are promising outcomes of intermittent fasting, there’s an
opportunity for further research related to performance and health benefits.
Many of the studies thus far were on overweight- or all-male subjects. If you
have blood sugar control issues, like diabetes or hypoglycemia, intermittent
fasting may not be a good fit. Alternatively, if you are pregnant or
breastfeeding, or take medications that are taken with food, speak to you doctor
before trying the 16:8 diet.

Take Home Message

Like any other diet, 16:8 intermittent fasting can be an effective strategy for
weight loss and exercise performance without requiring counting calories or
tracking macros.4 The 16:8 diet can also decrease fat mass while
preserving muscle, leading to lean gains.3 While more research is
needed, it shows promising results for body composition, performance, and
health-related outcomes. Intermittent fasting is one option for limiting total
calorie intake when trying to lose weight and maintain muscle. When practicing
this diet, remember to stay well hydrated, even while fasting, and to choose
balanced, healthy meals during the 8-hour eating period. Speak with your doctor
about any concerns before trying out this plan.


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Our articles should be used for informational and educational purposes only and are not intended to be taken as medical advice. If you’re concerned, consult a health professional before taking dietary supplements or introducing any major changes to your diet.

  1. Moro, T., Tinsley, G., Bianco, A., Marcolin, G., Pacelli, Q. F., Battaglia, G., … & Paoli, A. (2016). Effects of eight weeks of time-restricted feeding (16/8) on basal metabolism, maximal strength, body composition, inflammation, and cardiovascular risk factors in resistance-trained males. Journal of translational medicine, 14(1), 290.
  2. Mattson, M. P., Longo, V. D., & Harvie, M. (2017). Impact of intermittent fasting on health and disease processes. Ageing research reviews, 39, 46-58.
  3. Jane, L., Atkinson, G., Jaime, V., Hamilton, S., Waller, G., & Harrison, S. (2015). Intermittent fasting interventions for the treatment of overweight and obesity in adults aged 18 years and over: a systematic review protocol. JBI database of systematic reviews and implementation reports, 13(10), 60-68.
  4. Byrne, N. M., Sainsbury, A., King, N. A., Hills, A. P., & Wood, R. E. (2018). Intermittent energy restriction improves weight loss efficiency in obese men: the MATADOR study. International journal of obesity, 42(2), 129.
  5. Chaouachi, A., Leiper, J. B., Chtourou, H., Aziz, A. R., & Chamari, K. (2012). The effects of Ramadan intermittent fasting on athletic performance: recommendations for the maintenance of physical fitness. Journal of sports sciences, 30(sup1), S53-S73.
  6. Gabel, K., Hoddy, K. K., Haggerty, N., Song, J., Kroeger, C. M., Trepanowski, J. F., … & Varady, K. A. (2018). Effects of 8-hour time restricted feeding on body weight and metabolic disease risk factors in obese adults: A pilot study. Nutrition and healthy aging, (Preprint), 1-9.

Claire Muszalski

Claire Muszalski

Writer and expert

Claire is an experienced Health Coach and Registered Dietitian through the Academy of Nutrition and Dietetics. She has a Bachelor of Science in Biology and an MS degree in Clinical Dietetics and Nutrition from the University of Pittsburgh. Talking and writing about food and fitness is at the heart of Claire’s ethos as she loves to use her experience to help others meet their health and wellness goals. Claire is also a certified indoor cycling instructor and loves the mental and physical boost she gets from regular runs and yoga classes. When she’s not keeping fit herself, she’s cheering on her hometown’s sports teams in Pittsburgh, or cooking for her family in the kitchen. Find out more about Claire’s experience here.