16/8 Intermittent Fasting: A Beginner’s Guide

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.