Intermittent fasting is a powerful tool for improving your health and accelerating weight loss. However, your body needs to be nourished to thrive. This blog post shares how to get fasting working for you, so you are starving your fat cells, not yourself.
Intermittent Fasting At-A-Glance
- Fasting for fewer than 24 hours encourages fat loss by naturally reducing your caloric intake and encouraging low levels of the fat-storing hormone insulin.
- You can fast to a point where your body will burn muscle to get nutrients and lower its workload.
- The answer to the question, “How long is too long to fast?” is not clear. However, there is evidence that muscle may be breaking down as early as the first full day of fasting.
- Bottom Line: Working periods of fasting into your daily routine starves your fat cells. However, if you push your body too hard, it will be perceived as starvation, leaving you with results that you don’t want.
Intermittent Fasting: Starve Your Fat Cells (Not Yourself) [Video]
In this video, you’ll learn…
- How your body responds to intermittent fasting and why it works.
- What fasting is not.
- Advice on fasting timelines!
Fasting Works because It Starves Your Fat Cells
Fasting is nothing new. People have been practicing it for thousands of years for religious reasons or as a way of cleansing the body of impurities. It is only recently that it has become thought of as a weight-loss tool.
Terminology: Time-Restricted Eating (TRE) vs. Intermittent Fasting (IF)
These terms are often used interchangeably. Technically, TRE describes methods of fasting that allow you to eat every day within a shortened eating window. IF is used as an umbrella term to describe single- or multiple-day eating and fasting patterns.
Much of the weight loss benefit that is gained is due to two things. One is the natural reduction of calories that happens when you reduce the number of hours that you eat during a day. The other is the stabilization of blood sugar and insulin levels that happens due to the lengthened periods without food intake and the elimination of mindless snacking, specifically late-night snacking on high-carb foods.
Both of these benefits help you lose weight because they starve your fat cells. To best understand how that works, think of body fat as that closet in your house where you toss everything that you just want out of the way.
The things you throw in there have value, but you don’t have an immediate need for them. This is what body fat does for you. It stores excess food energy you consume, but don’t immediately need. Unlike the fixed-size closet in your house, fat-storage closets in your body can grow or shrink in size depending on energy needs and hormonal cues.
If fat loss is your goal, intermittent fasting naturally lowers your caloric intake, making it more likely that your body will need to pull energy from body fat. It also helps you maintain low insulin levels, which is a state that encourages energy to be pulled out of fat cells.
Consciously avoiding food for 12 to 20 hours a day is an action that causes energy to come out of fat cells and not refill, essentially starving the fat cells.
Intermittent Fasting is Not Starvation
The benefits of fasting sound fantastic, and they are. If 20 hours without food is a good idea, why not do 20 days and get the weight off asap? Unfortunately, you are working against your body’s needs if you do that. Intermittent fasting is not about starving yourself. However, you can fast to a point where your body will burn muscle to get nutrients and lower its workload.
To understand this, think of your metabolism as an engine. If you have a hearty metabolism with lots of muscle, it is a big truck, gas-guzzler. You want that because it burns through a lot of energy. You can eat hearty meals and stay trim because of your hearty metabolism.
If you restrict food intake for too long, you will no longer be able to sustain your big engine. Your body will burn up muscle to lower its energy requirement. You now have a small engine metabolism. If you resume eating as you once did, the excess calories will not get burned, but rather they will be stored. So, how long is too long too fast?
How Long is Too Long to Fast?
When fasting, you want your body to pull energy out of fat storage, not muscle. When you practice intermittent fasting, you may be thinking, “I want to lose weight.” However, your body is thinking, “I need to keep my person alive.”
If your body notices that there hasn’t been new energy coming into your system for a long time, it will look for ways to lessen its workload. An effective way to do that is to burn muscle so it has a smaller metabolic engine to support.
A study published in Nutrition Reviews in 2015 looked at the effects of intermittent fasting on body composition. It did this by reviewing many previously published studies to learn more about the effects of fasting on muscle. The researchers noticed that fasting could result in the presence of more urea nitrogen, which is a waste product that is created when the body breaks down proteins like the ones that make up muscle.
However, that increase does not show up until a person has been fasting for consecutive days. In other words, the brief fast you perform by skipping a meal and other shorter fasts lasting less than a day will not appreciably break down your muscles for energy (1).
However, there is evidence that prolonged fasting can result in some muscle breakdown. Exactly when this occurs is not clear. When I researched this topic for my book, I shared the chart below. On this chart we see that muscle may be breaking down as early as the first full day of fasting (as shown by the rise in urea nitrogen that occurs on Day 1). As the fast continues, nitrogen excretion rises until day 3, at which time it slows but does not stop (2).
Less than 24 Hours = Green Light (Longer = Use Caution)
It’s hard to predict the exact tipping point when a fast will begin to result in muscle loss. However, we do know that when individuals (who are adequately nourished) fast for fewer than 24 hours or alternate between fasting and feasting days, they don’t lose an appreciable amount of muscle (3). After a day of fasting, muscle breakdown may begin.
Where does this leave us with eating one meal a day (OMAD) fasting? Eating one time per day is an easy concept to grasp. The meal can last for 1 hour and can be thought of as a large meal without calorie or macronutrient limits. With that said, gorging on processed, refined carbs is not encouraged. However, the reality is that when eating healthy, whole foods, it is challenging to take in sufficient calories to meet your body’s needs.
Here again, stringing too many low-calorie days together tends to lower your resting metabolic rate, making long-term weight control difficult. Therefore, eating one meal a day may best be looked at as a way to throw your metabolism a curveball, which keeps it from becoming stagnant, rather than an everyday practice.
There is no magic switch that flips at 24 hours and one minute, turning your beneficial fast into a dangerous metabolic disaster. And, the length of a fast is not the only factor to consider. How you are nourishing your body when you eat, how active you are, and other metabolic factors that are unique to you play a role.
The bottom line is this. Your goal may be weight loss. But, your body’s goal is to keep you alive. To stay alive, it needs energy. When you are not fueling your system with food, you want that energy to come from body fat.
Carving hours out of each day to fast encourages the loss of fat from fat cells. However, if you push your body too hard, it will push back, leaving you with results that you don’t want.
I put together a fasting timeline that paints a picture you what is happening inside your body during a day of fasting. When you fast, your body uses stored energy to run your metabolism, repair tissues, and clean up damaged cells and debris. It is fun and motivating to have a timeline in front of you, showing you what is happening as the hours pass. Download the one-page fasting timeline for free here.
Thank you for reading and have a wonderful week!
(1) Tinsley, Grant M., and Paul M. La Bounty. “Effects of intermittent fasting on body composition and clinical health markers in humans.” Nutrition reviews 73.10 (2015): 661-674.
(2) Gillaspy, B. (2020). Intermittent Fasting Diet Guide + Cookbook: A complete guide to fasting strategies with 50+ satisfying recipes and 4 flexible meal plans. Alpha/DK Publishing.
(3) Bhutani, Surabhi, et al. “Improvements in coronary heart disease risk indicators by alternate‐day fasting involve adipose tissue modulations.” Obesity 18.11 (2010): 2152-2159.