Note: Some women have experienced extreme side effect when fasting. Things such as slowing of the metabolism, lost periods, and even early onset menopause. The reasons why are unclear, but it does have to do with a hormone called GnRH. Read the article “Intermittent Fasting for women: Important information you need to know” on PrecisionNutrition.com for a much better explanation on this than I can provide.
One of the more common questions I’ve received recently has been regarding fasting when it comes to health and fitness. This isn’t really a topic that has a quick answer. Any question involving it usually leads to more questions:
“Is fasting good for you, or is it bad?”
“What benefits and risks are there?”
“Will my body go into 'starvation mode' when I fast, and then, when I do eat, just store everything as body fat?”
“Will I lose all my muscle if I fast?”
So, I decided to spend some time on answering those questions.
What is fasting, and how does it work?
When we talk about fasting regarding fitness, what we usually mean is what’s known as “Intermittent Fasting” or “IF.” It basically means that you take only a certain block of time each day when you eat, and you fast for the rest of that time. So, out of the 24 hours of your day, you may only choose to eat in an 8 hour time block, lets say from 12pm-8pm.
Everything you eat gets broken down into various molecules used for different purposes. When your body is going through the process of digesting what you ate and sending things where they need to go, you’re in a “fed” state. Once it’s done, you’re in a “fasted” state. This can take anywhere from 3–6 hours depending on what and how much you ate.
Most of our bodies fluctuate between these two states several times each day. Unless you only sleep for 3 hours per night, you are already in a fasted state for most of your unconscious hours. The average person probably spends about 6–8 or so hours per day in a truly fasted state. What Intermittent Fasting does it flip the norm. Instead of being in a “fed” state most of the time and only a “fasted” one when you sleep or you’re too busy or too broke to eat, you intentionally spend most of your time fasted, and only a certain block fed.
What Are Some Benefits of Intermittent Fasting?
I have to admit, when I first heard of people fasting for fitness-related reasons, especially weight-loss, I thought it was a horrible idea. That’s because I know that lifestyle change and sustainable habits are the best strategies for long term fitness.
But, I eventually had to face the fact that there are exceptions to that. Sometimes, people need things to jump-start them or to help them take the next step toward that goal. Fasting can be that for some people.
1. IF can help people better control their caloric intake. Energy balance, calories in vs calories out, is truly the key to reaching weight goals. But some people struggle more than most with overeating. This is often because of long days and/or high-calorie foods. IF can help with this. If you only allow yourself 8 hours per day, or even 6 hours, in which you can eat, well, then you can eat a lot more during that time because you aren’t spreading it out over a typical 12-plus hour period that most of us operate within.
I want to note here that this works very well for some people, and not so well for others. I, personally, hate fasting. When I go for more than 8 or so hours without eating, I feel lightheaded and strange. I use words in weird places and snap at people. My wife tells me to eat something. But some people feel energized and free. Studies have shown no real difference in terms of weight loss between people who fast and people who follow a more traditional eating plan, so it really all comes down to what you prefer.
2. IF does have some physiological benefits. There is a process known as “autophagy” that has to do with destruction of cells in the body. This process relates to maintaining muscle, and also with some anti-aging processes. Fasting also has been linked to reducing inflammation, improving levels of growth hormone, and more. (Source: Muscleforlife.com)
What it really comes down to is what you like and what you are willing to try. Fasting does have some benefits, and I’d recommend giving it a try and seeing whether you like it. If you do, go with it! If you don’t, don’t force it. Do what works for you.
But Won’t I Go Into “Starvation Mode"???
People sometimes think that fasting will make them go into “starvation mode”, and that, when they eat again, their bodies will store fat quicker than C-3P0 will tell you the odds.
Well, this depends on how long you fast, but it isn’t really true, and isn’t true at all when it comes to the intermittent fasting we’ve been talking about (only eating for a certain block of time each day).
A study showed that a person’s basal metabolic rate (the rate at which you burn calories while you’re just sitting on the couch) didn’t even begin to decline until 60 hours of fasting, and it wasn’t by much even then. Starvation mode does exist, but it really only happens after 3 or more days of not eating.
So, unless your time block of eating is measured in days and not hours, this isn’t something to worry about.
Will I Lose Muscle If I Fast?
Fasting doesn’t seem like it’d be the most effective means of gaining or maintaining muscle. Let’s talk about that.
First off, how often you eat isn’t nearly as important as what and how much you eat. There are some benefits of eating protein every few hours, but not doing so isn’t going to kill your progress.
Here’s the overly-sciency part, but I’ll break it down. Glucose, received mostly from carbs, is a source of energy for your body. If your body isn’t receiving the carbs, it will get glucose from other places. It can pull it from glycogen, much of which is stored in the liver and muscles, but it can also pull from amino acids found in the muscle.
The process that the body uses to get the glucose from the amino acids is much more difficult than the one to pull from glycogen, and like us, our bodies like to take the path of least resistance. So, until your stores of glycogen in your liver are depleted, your body won’t turn to the amino acids in your muscles for energy.
Most people’s livers store enough glycogen to last them for anywhere from 6–24 hours of fasting, depending on activity. One study shows that by 16 hours of fasting, the body was drawing about 50 percent of its glucose from the amino acids. By hour 28, it was taking 100 percent from it. So, most of the time, if you’re fasting for more than 12 hours, the body may begin to turn to the amino acids in your hard earned muscle for its glucose.
So, if you’re trying to build or maintain your muscle, the best plan is to not fast for more than 16 hours at a time (including sleep time). But if you’re working out during the fast, that time period is significantly reduced because the activity is causing your body to draw on its glucose much more quickly.
Should I Workout While Fasted?
“Fasted training” is when a a person performs their workout while their body is in a fasted state. A fasted state is when a person’s body has finished digesting food and sending molecules where they need to be, and no more food has been consumed. This can be around 6 hours after consumption, depending on what was eaten.
There are a few reasons that a person would want to train fasted (apart from insanity):
It can actually help you burn more calories when you are in a fed state.
It is one of the very few ways that you can truly target a specific part of your body for fat loss, as it can target the abdominal region due to increased blood flow experienced when fasting.
You just like the feeling of working out fasted.
These are some good reasons to consider it if you are trying to lose body fat. The person who I would most recommend give this a try would be a person who is trying to lose a significant amount of body fat. Most of these benefits apply to them.
But, if you are someone trying to just build some muscle, or you are losing fat but are trying to get stronger and build muscle in the process, it may not be the best idea. Here’s why:
Fasted training can burn muscle for energy (see above).
Workouts are usually horrible because you have low energy and feel like a zombie. And not the kind that runs.
The first one can be largely prevented by supplementing with HMB. It’s one of (if not the) only times I would ever tell you to not try something without using a supplement. HMB is perfect for fasted training, because it prevents muscle breakdown while not breaking your fasted state.
In conclusion, if you are trying to lose body fat and want to try fasted training, go for it! See if it helps. It can be a jump start, can help you break through a plateau, whatever. But if you’re trying to add muscle, think twice about this. And if you decide to give it a go, make sure you supplement.
Intermittent Fasting is a valid fat loss strategy. It just depends on if it works well for you, and the only way to know is to give it a try. If you do so, it may be a good idea to start with a larger block of time during which you an eat and decrease it gradually to see how your body responds.
Comentários