16/8 Intermittent Fasting: A Beginner’s Guide

16/8 Intermittent Fasting: A Beginner’s Guide

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16/8 Intermittent Fasting: A Beginner’s Guide

Posted a year ago

Brian Stanton

Brian Stanton


If Goldilocks were choosing a fasting regimen, she might choose 16 8. The fasting periods are just right—not long enough to be uncomfortable but not short enough to be ineffective. 

And you only need to lock in the habit once. Once 16 8 fasting (often written as 16/8 fasting) becomes habitual, the potential benefits—weight loss, metabolic health, etc.—accrue automatically. 

So is 16/8 the perfect starter fast? (Hint: Goldi isn’t a beginner.) What benefits and risks should you expect? And how can you implement 16/8 intermittent fasting into your life?

Take four minutes to read on. You’ll get your answers. 

Intermittent Fasting Basics

Intermittent fasting is the practice of regularly taking breaks from calories. These breaks help your body move from energy storage to energy-burning mode:

  • Energy storage mode. When you feed, your body stores excess energy as body fat.
  • Energy burning mode. When you fast, your body accesses body fat for fuel. 

Both states (fed and fasted) are essential for human flourishing. Oscillating between the two helps us stay metabolically healthy

We evolved to oscillate, but lately, we’re stuck in storage mode. (Fourth meal, anyone?) And so we have an obesity crisis

Intermittent fasting is like hitting a reset button. We reset to burning energy occasionally. 

There are two main flavors of intermittent fasting:

  1. Weekly fasts like alternate day fasting and 5:2
  2. Daily fasts like 12/12, 16/8, and OMAD

Today we’ll focus on daily fasting, also called time-restricted feeding (TRF).[*] When you practice TRF, you consume all your calories in a set window each day. 

Which brings us to 16/8. 

What is 16/8 Intermittent Fasting?

16/8 fasting entails eating all your calories in an 8-hour daily window. The other 16 hours are fasting hours. 

In practice, this might mean skipping breakfast, having your first meal at noon, and finishing dinner at 8 PM. Or you could start (and end) earlier, with breakfast at 9 AM and your last bite at 5 PM. 

If possible, feed during daylight hours. Along with light, food regulates your circadian rhythm, the 24-hour wake/sleep cycle that influences a big chunk of the human genome. 

Fasting overnight explains many benefits of TRF.[*] You sleep better, your genes function better, and everything feeds back in a virtuous cycle. 

And you don’t need a 16-hour fast to get these circadian benefits. An overnight fast of 12–13 hours will suffice. 

That’s why it’s wise for beginners to start small. See how overnight fasting feels, then scale up if you think you need more. 

How many calories to eat during intermittent fasting 16/8

In principle, time-restricted feeding doesn’t limit how much you eat. Instead, it limits when you eat. 

Even so, people tend to eat fewer calories on 16/8. When you have a shorter feeding window, you tend to eat less. 

Eating less is the most reliable way to promote weight loss. And skipping breakfast with 16/8 is a reasonable method of accomplishing that goal

The bottom line is that you probably don’t need to restrict calories consciously. But if you’re struggling to lose fat on 16/8, consider using Carb Manager to track and moderate portions. 

16/8 Intermittent Fasting Meal Structure

Rather than clog this blog with a complete 16/8 intermittent fasting 7-day meal plan, let’s cover the principles of TRF meal structure. Then you’ll be able to design your own schedule. 

The first principle is to prioritize protein. With fewer hours to feed, you have fewer meals to consume this crucial macronutrient for muscle maintenance, DNA repair, hormonal health, and much more.

If you want to stay strong, your meals should center around meat, fish, eggs, or another protein source. Aim for 1.2–1.6 grams of daily protein per kilogram bodyweight.[*] (100 daily grams is a good target for most people.)

Beyond protein, fill your plate with nutrient-dense whole foods. We’re talking about vegetables, fruits, nuts, seeds, and healthy fats—not refined, processed foods full of empty sugar calories. 

Remember that you’re eating in a compressed window. Make that window as nutritious as possible. 

Potential Benefits of 16/8

We already discussed the circadian benefits of time-restricted feeding. These benefits reverberate across all aspects of health. 

In clinical trials, 16/8 fasting has also been shown to promote:

  • Weight loss[*]
  • Lower blood sugar[*]
  • Reduced inflammation[*]
  • Other markers of improved metabolic health

These benefits, to be clear, are most apparent in obese and diabetic populations.  

Potential Risks of 16/8

One risk of 16/8 is muscle loss. You can maintain muscle on 16/8—studies have looked at this[*]—but you must consume adequate protein in tandem with a strength training program. 

Another risk is that you’ll get headaches, muscle cramps, fatigue, and other fasting-related side effects. Sometimes, consuming more electrolytes (especially sodium) can solve the problem. Other times, you’ll want to adjust your protocol. 

Pregnant and nursing women, growing children, underweight people, and people with eating disorders should avoid fasting entirely. And if you have a medical condition (i.e., type 2 diabetes), consult a healthcare professional before making any moves. 

3 Quick Tips for Implementing 16/8

Let’s conclude with some practical advice on trying 16 8 intermittent fasting. 

#1: Determine your health goals

Don’t fast because it’s “healthy.” That’s too vague. Decide what you want to achieve, then experiment. 

An obese person will have different goals than a lean, athletic person. They have more fat (and less muscle) to lose.

Always weigh any fasting benefits against the risk of muscle loss. You want a protocol that’s “just right,” and 16/8 might not fit that bill.  

#2: Work up to it

If you’re new to fasting, don’t start with 16/8. Start with a 12-hour overnight fast. 

Go from dinner to breakfast (7 to 7, say) without eating. Let your body adapt, and notice any improvements in sleep, mood, body composition, etc. 

Once you’re comfortable, expand your fasting window. 

#3: Measure 

Some people can wing it on 16/8 and get results. But when starting out, consider tracking your progress. Use Carb Manager to:

  • Log meals and track calorie intake
  • Track macronutrients (especially protein) and micronutrients
  • Count down fasting periods with our IF tracker
  • Create custom fasting protocols, or follow well-worn regimens like 16/8
  • Track body weight, sleep, blood sugar, and other health metrics

Eventually, your new eating patterns will become habitual. Then you can return your attention to puppies, rainbows, and sunshine. 

Comments 16

  • Moonshadow132023

    Moonshadow132023 a year ago

    Is it ok for bariatric patients to fast. My surgery was in 2016.

    • Maxiimania

      Maxiimania a year ago

      Fastic is good if your fasting if not a full member on here I found I kicked off a good weight loss quick with 19 hr fasts it’s hard to start off with that so you might want to slowly work up to it .

      • HisNefertiti

        HisNefertiti a year ago

        Yes, water, black coffee, and tea with no sugar added.

        • KiminMO

          KiminMO a year ago

          Can I drink black coffee during 16/8 fast?

          • FantasticAvocado918249

            FantasticAvocado918249 a year ago

            Does drinking non alcoholic wine break your fast? Or just include in your window.

            • SplendidArugula805948

              SplendidArugula805948 a year ago

              From what I’ve read, no calories should be consumed in your fasting period. https://www.hopkinsmedicine.org/health/wellness-and-prevention/intermittent-fasting-what-is-it-and-how-does-it-work

          • SpectacularMacadamia366183

            SpectacularMacadamia366183 a year ago

            Just wondering….does drinking Zipfiz break a fast according to Carb Manager?

            • SplendidArugula805948

              SplendidArugula805948 a year ago

              I think that depends on the calorie count in zipfiz. If it’s more than zero, then probably yes.

          • angelranch05@aol.com

            angelranch05@aol.com a year ago

            I started Mounjaro 7 weeks ago. For my T2D. The IF tracker has worked great since being on the medication I’m not really hungry but I know I need to get my protein in and make myself accountable for what I’m eating. The app actually helps me keep track of what I’m eating so that I know that I’m eating enough and not too little. Not always easy. But I’m down 15lbs since April

            • MarvellousCauliflower104049

              MarvellousCauliflower104049 a year ago

              Congrats on your weight loss and commitment 🎉👏

          • ArdentC97

            ArdentC97 a year ago

            I fast on a 14/10 ration and it works; especially with regulating my period. I also try fasting a full daytime fast three days a month - but that's for a religious reason not for health lol.

            • TwoSmurfs

              TwoSmurfs a year ago

              How many days in a row should you fast for in the week?

              • angelranch05@aol.com

                angelranch05@aol.com a year ago

                I do the fasting Monday through Friday. But I’m also on Mounjaro for my T2D. I eat low carb 5 days and do carnivore for two days out of the week.

            • dcono4faith6361

              dcono4faith6361 a year ago


              • SuperRadish792669

                SuperRadish792669 a year ago

                Love IF , i have lost 3.5 stone in 3 years 😁👍

                • BurningThyme

                  BurningThyme a year ago

                  CONGRATS! ! !