Hunger – When to Eat | When to Fast

Hunger – When to Eat | When to Fast

Video | True Hunger vs. False Hunger | Using a Hunger Scale | Fasting Schedules | Metabolic Flexibility

The average person’s daily calorie consumption has increased by 24 percent since the 1960s (1).

Many factors contribute to this calorie explosion, from the processing of foods to the three-meal-a-day plus snacks mindset, to external cues that make us want to eat even when we aren’t hungry, think the late-night pizza commercial and the smell of fresh-baked cookies. 

These extraneous factors make it very hard to tell the difference between true hunger, which is driven by your body’s physiological need for fuel, and false hunger, which is driven by other factors, including habits, routines, whims, and scarcity.

Learn how to tell the difference, and you create an effortless way to cut out hundreds of unneeded calories each day. 

This blog post shares my hunger scale so you have a tool to help you gauge when to eat and when to fast. And I’ll share the trick for staying in the middle range so you move through your day feeling satisfied. 

When to Eat | When to Fast – At-A-Glance

  • True hunger requires food to satisfy it; false hunger does not. 
  • False hunger is driven by extraneous factors (i.e., habits, routines, whims, scarcity)
  • Rating your hunger level using a hunger scale helps you get back in touch with true hunger.
  • A metabolically flexible body can run efficiently on different fuel sources (i.e., glucose or fat), making fasting easier.  
  • You can train your body to be more metabolically flexible by eating low-carb, whole foods.  

Hunger – When to Eat | When to Fast [Video]

In this video, you’ll learn…

  • How to use the Hunger Scale.
  • The difference between extended fasts and time-restricted eating.
  • The definition of metabolic flexibility and how to become metabolically flexible.

True Hunger vs. False Hunger

Years ago, I put together a simple hunger scale to help people tell the difference between true hunger and false hunger. True hunger requires food to satisfy it; false hunger does not. 

The problem is that telling the difference has become challenging. Innocently visit a fast-food restaurant, pick up a chocolate-coated energy bar in the checkout aisle, or stop into the local coffee shop for a flavored latte, and your tastebuds and brain chemistry are met with just the right mix of sugar, fat, and salt, to stimulate – not satisfy – your hunger. You end up downing 500 or more calories and wonder why you feel like you could definitely still go out for an ice cream cone. 

Regaining Control

The first step to regaining control so you only consume the amount of food your body needs is getting back in touch with true hunger.

The second step is getting your body to a point where hunger never feels like an emergency, so eating or fasting is your choice, with no need for willpower.

Using a Hunger Scale

You can use a hunger scale to tackle the first step and get back in touch with true hunger.   

Using a Hunger Scale

Note that the scale runs from 0 to 10, with “0” meaning you are starving and “10” meaning you are stuffed. Think of your hunger level as you would your car’s gas tank. When your tank is nearing empty, you need to refuel. When it is full, you don’t. 

The scale itself is simple. However, you may find it surprisingly hard to pinpoint where you land on the scale at any given moment. It is a skill that many of us have lost. 

Hunger Prompts

To bridge that learning gap for you, let me give you some prompts:

  • You are at 10 if you need to unbutton your pants because you are uncomfortably full.
  • You are at 9 if you forced yourself to eat everything, despite knowing it would push you over the edge – Think having the dessert that you know you should have passed on. 
  • You are at 8 if you just ate a big meal but feel comfortable.
  • You are at 7 if a couple of hours have passed since your big meal or you just had a lighter meal.
  • If you are at 4, 5, or 6, you are in the satisfied range; your body feels comfortable, your energy is good, and eating does not, in any way, feel like a pressing matter. This is where you’ll feel the most comfortable, and I’m going to give you the way to stay here in a moment. 
  • You are at 3 if hunger just popped into your head, but you do not feel an immediate need to eat.
  • You are at 2 if hunger is annoying but manageable. This is a common level to be at a half hour before lunch or dinner. 
  • You are at 1 if hunger is distracting you or you are feeling low on energy, “hangry”, or have trouble concentrating on your work.
  • You are at 0 if hunger has completely hijacked your brain. You cannot focus on anything other than food. 

Obviously, you don’t have to wait until you are at 0 to eat. If you are at 3, for instance, and you are meeting someone for lunch. You can certainly eat, but knowing that you are a 3 will help you make better food choices or help you feel confident that you can eat a lighter meal and walk away feeling comfortable. 

If you find that you have the desire to eat, but when you rate your hunger, you fall at 7; your body does not need food. This is false hunger, and it is likely being driven by an extraneous factor, like an enticing TV commercial, the smell of a favorite food, or even scarcity – it’s the last cookie on the tray. If you don’t eat it now, you’ll miss out. 

You will need to practice with this to get good at it. I recommend checking your hunger level every couple of hours or at least right before a meal as you are getting familiar with using it. 

Extended Fasts vs. Time-Restricted Eating

Practice will improve your ability to tell true hunger from false hunger, even when you are in the middle of a longer fasting period. 

There are daily fasting patterns, which more accurately are termed time-restricted eating. And there are extended fasts lasting longer than 24 hours. 

When you are practicing daily fasting routines, like 16 or 20 hours of fasting (commonly referred to as a 16/8 or 20/4 fasting schedule), the longer you can stay in the middle or satisfied range of the hunger scale, the more content you’ll feel. Your ability to do this has a lot to do with your food choices and your ability to train your body to become more metabolically flexible, which I will get to in a moment. 

Extended Fasts vs. Time-Restricted Eating

Extended fasts are not for everyone. It feels like a way to force your body to lose weight, but much is yet to be learned about long-term consequences for your metabolism or muscle mass when extended fasts are too frequent or too long. 

I will say, however, if you are fortunate enough to have a doctor who is willing to advise you on using a longer fast, or you use them sparingly, maybe a couple of 36-hour fasts per month, that is another thing entirely. 

Bringing the focus back to hunger. On an extended fast, and even one-meal-a-day fasting, you can expect true hunger to show up. That hunger will ebb and flow, and as long as you are not feeling shaky or ill, you can ride it out. But you will have a much easier time doing so if you, again, make the right food choices and train your body to become more metabolically flexible. What is that, and how do you do it? 

What is Metabolic Flexibility? 

The easiest way to think about metabolic flexibility is to compare it to a hybrid vehicle. Hybrids can run well on different fuel sources: gas or electric. A metabolically flexible body is similar in that it runs efficiently on different fuel sources. In the case of the body, those fuels are glucose and fat, and whatever is most available is what it will run on. 

metabolic flexibility

To be more exact, that fuel could be glucose from your diet or stored glucose, which is glycogen, dietary fat or stored fat.

If glucose is low enough, your liver turns some of the available fat into ketones, providing an additional type of fuel that is particularly beneficial to your brain.

Learning how to become metabolically flexible comes with perks. Because your body always has an option to meet its energy needs, you experience sustained energy and freedom from hunger. And, because a portion of your energy is coming from fat, you have an easier time with weight loss.

How to Become Metabolically Flexible

Anyone can improve their body’s metabolic flexibility. Your food choices are the most important factor in getting there. 

The first step is choosing whole foods over processed and refined foods. Think of foods that still resemble the original plant or animal they came from rather than those in a box.

The slower-absorbing whole foods trickle energy into your system, and the longer this process takes, the longer hunger stays away.

An additional dietary step you can take is lowering the overall carbohydrate intake of your diet.

How to Become Metabolically Flexible

Eat a Low Carb Diet

Carbohydrates break down into glucose. If you limit the glucose coming in, your body must move to the next available fuels, which are glycogen and fat. If enough glucose is depleted, your liver makes ketones out of fatty acids raising your metabolic flexibility to a higher level.

The interesting thing to note is that you don’t need to be on a ketogenic diet for your body to make ketones. Ketones are needed by your brain when glucose is too low, so any action you take that depletes glucose could lead to ketone production.

For instance, I do not follow a keto diet, but I do eat a low-carb diet and practice intermittent fasting, so it is not unusual for me to test my blood in the morning and notice the presence of ketones.


You can see how the snowball can start rolling. As you consistently choose low-carb, whole foods, your body becomes more and more metabolically flexible. When that happens, hunger stays under control because your body can tap into body fat anytime it needs it. It is no longer reliant on you eating glucose. 

This controlled hunger not only makes it much easier to stretch out periods of fasting but also makes it easier to rate your hunger using the hunger scale. That skill puts you back in touch with true hunger giving you just enough clarity to avoid mindless eating. It doesn’t mean that you won’t be disappointed. Eating is a fun activity. But if you have a bigger goal, like weight loss, it allows you to stay calm and in control rather than feeling like food is in control of you. 

Thank you for reading and have a wonderful week!


(1) Gould, Skye. “charts that show how much more Americans eat than they used to.” Business Insider.–2017.–10.05.–URL: https://www. businessinsider. com/daily-calories-americans-eat-increase-2016-07 (date of application: 10.01. 2021) (6).

About the Author

Becky Gillaspy, DC, is the author of The Intermittent Fasting Guide and Cookbook. She graduated Summa Cum Laude with research honors from Palmer College of Chiropractic in 1991. 

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