If food is fuel for your body, what happens if you forgo a meal and then head to the gym to exercise in a fasting state? Well, I believe it can positively change the way your body burns fuel — if it’s done right. It may even help you reach your fitness goal in the shortest amount of time! Sounds awesome, right? Well, it depends. When you eat or don’t eat, plays a major role in your success. So, to determine if exercising in a fasting state is right for you, let’s first learn how the body fuels itself.
What is exercising in a fasting state?
Exercising in a fasting state simply means exercising on an empty stomach, preferably after not eating for several hours. I personally think the best time to do this is in the morning when your last meal was dinner the night before. The combination of fasting for 12 hours and exercising maximizes your body’s ability to efficiently shed fat. And if you’re an endurance athlete, it may also help your body regulate fuel more efficiently. Here’s what else I found out…
Exercising in a fasting state burns more fat
Some research shows that doing cardio on an empty stomach, first thing in the morning burns more body fat. A British study from Northumbria University set out to find out if exercising after an overnight fast was undermined by an increased appetite and eating more food later in the day. What researchers found was that participants who had exercised in a fasting state actually burned almost 20 percent more fat than those who had eaten breakfast before their workout.
It may also prevent you from overeating
When it came to an increased appetite later in the day, here’s what the study found. Following exercise, participants were given a chocolate milkshake. Then, later in the day, they were fed a pasta lunch, which they were asked to eat until they felt “comfortably” full. Researchers assessed and calculated each participant’s lunchtime consumption of energy and fat, also considering the amount of energy and fat burned during the morning exercise. They discovered that those who had exercised in the morning did not consume extra calories. They also weren’t hungrier during the day, even though they had exercised in a fasting state. That means you won’t undermine your workout by overeating later.
What does exercising in a fasting state do to muscles?
Being in a fasting state means you’ve gone without food for about 12 hours, assuming you haven’t had breakfast. By now, your food has not only been digested, but the fuel it normally provides has depleted. So, your metabolism shifts. Here’s where things can get dicey. Yes, your body will begin to use your fat as fuel. But, before you get too excited, there is something else you need to consider.
When your glycogen reserve is low, your body also looks at breaking down protein — also known as your muscles’ building blocks for fuel. So, while you will shed more fat when exercising in a fasting state, you may also lose more muscle.
What happens to the metabolism?
Glucose and fat are main sources of energy for the body. If glucose is not available, then your body will adjust by using fat without any harmful health effects, which is a good thing. This is a natural part of life. In fact, periods of low food availability, fasting or even self-induced starvation have always been a part of human history. One of the best examples of this is civil rights activist Mahatma Gandhi. At 74 years old he lived for 21 days without eating food during a hunger strike — and survived! But going without food for 12 hours does not mean you’re starving, right? Well, your body may beg to differ.
Going without food for an extended period will slow your metabolism, which can make losing weight more difficult over time, says Dr. Kelly Pritchett, assistant professor of sports nutrition at Central Washington University. Meanwhile, to prevent starvation, your body will adapt to the number calories you give it. So, if you’re frequently fasting, your body will compensate by burning fewer calories per day to keep your energy going.
Fasting versus non-fasting exercise
Slow metabolism, although not directly linked to weight gain, could be behind the study published in the Journal of the International Society of Sports Nutrition, which found no significant difference between women who fasted during exercise and women who did not.
Twenty female volunteers were randomly split into two groups. One group exercised after an overnight fast, and the second group ate a meal prior to exercising. Both groups exercised steadily for one hour doing aerobics, three days per week. In addition, a meal replacement shake was given either before exercise for the non-fasted group or immediately after exercise for the fasted group. Participants were also given a low-cal diet plan to follow.
Not-surprisingly, both groups showed a significant loss in weight and fat. But surprisingly, there were no major differences between each group. This means that although the body changes with exercise and a low-cal diet, no real changes occur if you exercise in a fasting state.
Don’t throw in the towel just yet
Will you lose more fat and weight than someone who is simply exercising, and on a calorie restricted diet? That’s up for debate. But there are a few ways that you can optimize your workout and shed fat. Food and exercise obviously play a key role in reducing fat and keeping it off for good. Here’s what I do:
- If I’m skipping breakfast for a fasted workout, I’ll have my lunch a little earlier and dinner a little later. I eat no later than 7:00 p.m. to maximize fat-burning.
- I keep calories in check. Remember, no matter how hard you workout, if you don’t keep your calories in check, you won’t maximize weight loss.
- With that in mind, exercising in a fasted state would be foolish if you’re still eating a diet full of junk and processed foods.
If you’re new to exercising in a fasting state, don’t push yourself too hard, it will just be counterproductive. A study from the Department of Biochemistry at East Carolina University shows that maximizing workout intensity in a fasted state can actually decrease performance, even when carbs are consumed while exercising.
And, if the thought of getting up early, with an empty stomach, to perform a grueling workout feels more like torture, then maybe this exercise trend is not for you. But, if you can push through, exercising in a fasting state may even do more than just control your weight. Research suggests it may have additional health benefits, such as normalizing your blood pressure, reducing stress, lowering LDL and total cholesterol levels, and improving your circulation. Just do it and see where it takes you!