Exercise And Intermittent Fasting: Burn Fat And Build Muscle On If
This article was co-authored by Kyle Kenny. Kyle Kenny is a Master Trainer, Certified Personal Trainer, and the Owner of KennyTRY Training. With more than seven years of experience, he specializes in helping people achieve their fitness goals by creating individualized meal programs, training regimens, supplementation systems, vitamin lists, and workouts. Kyle has multiple Personal Training Certifications and a Fitness Nutrition Specialist Certification through the National Academy of Sports Medicine.There are 11 references cited in this article, which can be found at the bottom of the page. This article has been viewed 21,158 times.
Intermittent fasting is a diet designed to take the hassle out of counting calories by restricting when you can eat to specific times known as feeding windows. IF has been shown to help lose and maintain weight, and you can combine it with a healthy exercise regimen to burn even more fat. However, there are a few ways you can maximize your exercise while youre following an IF protocol. Fasting can make you feel tired or fatigued, but if you feel light-headed, dizzy, or exhausted, hold off on exercising until you feel better.
What Does The New Research On If Mean For You
For most people , a time-restricted eating approach appears to be a safe strategy that is likely to produce some weight loss, assuming you are not changing your current dietary pattern .
The weight loss effects of time-restricted eating derive primarily from achieving a negative energy balance. If you maintain your regular diet and then limit the time window during which you eat, it is likely that you will eat a few hundred fewer calories per day. If this is sustainable as a lifestyle, it could add up to modest weight loss that can produce beneficial improvements in cardiometabolic markers such as blood pressure, LDL cholesterol and triglyceride levels, and average blood sugar.
But and this is a big but if you are overcompensating for the time restriction by gorging yourself during your eating window, it will not work as a weight loss strategy. And it may indeed backfire. The other two levers in your dietary pattern the quantity and quality of what you eat during your eating window still matter immensely!
Is It Better To Workout Fasted
Some say that intermittent fasting and fasted exercise has a beneficial effect on the bodys hormones, insulin and growth hormone in particular.
Fasted training is more than just OK, its actually the best way to improve both your health and your body composition.
On the flip side, others claim that high-intensity workouts shouldnt be done following fasting periods. Your metabolism will slow down, your performance will suffer, the levels of various stress hormones, such as cortisol, will rise and you run the risk of losing rather than gaining muscle.
However, contrary to what the name suggests, human growth hormone doesnt have much to do with muscle growth in adults. Even growth hormone injections dont do much for muscle protein synthesis, a prerequisite for building muscle.
Studies do show that early time-restricted feeding, which means eating most of your calories earlier in the day, improves whole-body insulin sensitivity independently of its effects on weight loss .
This gives it a potential role to play in improving cardiometabolic health in people with type II diabetes or pre-diabetes.
However, insulin sensitivity will tend to improve with calorie restriction and weight loss, irrespective of whether that weight loss is achieved with fasted or non-fasted exercise.
The idea is that doing some of your training in a fasted state with low glycogen stores can improve performance when you eventually compete with glycogen stores fully topped up.
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So How Should You Time Exercise While Intermittent Fasting
Poyourow recommends timing your fast so your workout happens at the end of it. Is it going to be painful to hit the gym after, say, a 16-hour fast? Yesbut you’ll get used to it.
It will likely take a few weeks for your body to adjust and during that time you should take it easy, Poyourow says. But your body can and will adapt after which you should be fine to stick to your regular schedule, even on the days you are fasting.
The important thing to keep in mind for people who do IF and exercise a lot is that you have to keep drinking water, lots of water, Poyourow says. You need to drink one-half to one gallon of water per day and if you sweat a lot, consider adding an electrolyte tablet, he advises.
You might also maximize your weight-loss potential by saving your sweat session for the end of your fast. Studies have shown that it takes a good 10 to 12 hours to burn up your glycogen stores and switch to mainly burning fat, he explains. So working out at the end of your fasting period means youll be using more of your stored fat for energy.
Want To Learn More About Fasting?
Plus, your muscles will be primed by your workout to better absorb the protein and nutrients from your breaking the fast meal, he adds.
The key is to listen to your body and learn to recognize what is normal you-can-push-through-it pain from working out and what is unusual for you, he says. If it hurts in a bad way, stop doing it.
What Are The Benefits Of Intermittent Fasting
Greater Fat Burning: Research has shown that fasting for relatively long periods may result in greater fat burning and accelerated fat loss, even when daily calorie intake remains the same. Most people find that they can have a few more of their favorite cheat foods during the feeding window and still see results
Adherence: IF is relatively easy to do, and it’s a diet you don’t have to discontinueâever. You can do intermittent fasting long term with no adverse health effects. Instead, you’ll see health benefits from IF.
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Supplements During Your Feeding Periods
Two of the most important supplements to consider are protein and creatine.
While protein supplements arent necessary if you get enough protein from foods, they can be a convenient way to ensure that you get enough.
Especially if you are physically active, protein supplements may help improve muscle size and exercise performance .
In addition to protein, creatine supplements can support your muscles.
Creatine is a molecule that is found naturally in your body. You can increase the amount of creatine in your cells via dietary supplements .
Creatine supplements are particularly helpful if you exercise. It has been estimated that creatine increases the strength gains from weight training by 510%, on average (
16 ).
Whats more, some of the health benefits of intermittent fasting are probably due to the fact that your body is not receiving any nutrients .
This mild stress on your body may strengthen it to fight off larger threats, such as disease, in the future .
If you take supplements containing amino acids during your fasting periods, you are signaling your body that you are not fasting .
Additionally, if you get enough protein in your feeding period, fasting for 16 hours does not appear to be detrimental to your muscles, compared to a normal diet .
Overall, it is unlikely that you need to take dietary supplements during your fasting periods. Some supplements, like creatine, may even be more beneficial when taken with food (
Can You Build Muscle Training Fasted
Yes, you can build muscle training fasted. Whether youll build as much muscle as you would have done had your training been done after a meal is open to debate, for the reasons I mentioned earlier. But resistance training, even in a fasted state, will still stimulate muscle gains.
To maximize the muscle-building response to a bout of heavy lifting, especially if its done on an empty stomach, you want to get some post-workout protein inside you .
Training first thing in the morning in a fasted state, then waiting until the afternoon before eating any protein, will almost certainly slow the rate at which muscle is gained.
That post-workout protein can be in the form of regular food or even just a protein shake. Some whey protein mixed with water will do the job just fine.
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Can You Exercise While Intermittent Fasting
The short answer is yes, says Jonathan Poyourow, RD, CSCS, a sports dietitian, professional chef, and associate professor of nutrition at Johnson & Wales University. Do you have to do intermittent fasting to achieve your diet or fitness goals? Absolutely not, Poyourow explains. But if you want to try fasting, there are ways to make it work with your workouts.
The longer answer is that it depends on many factors, including your age, overall health, fitness level, goals, nutrition, and lifestyle.
But if you consider yourself a serious athlete, it might not be the best fit. I do not support combining intermittent fasting and working out, especially for athletes, says Rachel Fine, RD, a registered dietitian nutritionist, a board-certified specialist in sports dietetics, and owner of To The Pointe Nutrition. For people who work out a lot, the goal of a diet should be fueling the body and that can be hard to do with intermittent fasting.
Working out, particularly when you do it almost daily, puts a lot of stress on your physical and metabolic systems and to support your workouts and recover properly you need a certain amount of calories strategically eaten throughout the day, Fine explains.
Ultimately its about whether it fits with your lifestyle and your body, its very individual, Poyourow says, adding that he recommends talking to a doctor before starting any type of fasting plan if you have any health concerns.
Intermittent Fasting For Healthy Weight Loss
As weve said, not all weight loss is the same. Its essential to make sure youre losing weight in a healthy way. Can intermittent fasting help with healthy weight loss?
Here, the data are conflicting.
On one hand, intermittent fasting can help improve metabolic health by reducing blood sugar and blood pressure while also improving blood lipid levels.4
On the other hand, three trials suggested that intermittent fasting may not lead to greater weight loss than usual care, or even worse may lead to greater loss of lean muscle mass than usual care or continuous calorie restriction.5
A healthy weight loss intervention also should be relatively easy to comply with and maintain long-term. Fortunately, intermittent fasting may fit that criteria.
One study reported that working adults found time-restricted eating with an eight-hour eating window easy to comply with and maintain for three months.6
That fits with frequent clinical experience suggesting many people easily adapt to time-restricted eating, especially when they follow a low-carb or high-protein diet that helps improve satiety and reduce appetite.7
So, in terms of convenience and ease in your approach to healthy weight loss, intermittent fasting seems to be a winner.
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Improve Peak Power And Vo2 Max
Studies show that fasted training can improve peak power and VO2 max.
Translating that into weightlifting benefits, fasted weight training could help improve lifting output over the duration of a workout.
VO2 max is vital to endurance athletes, but it also has a place in the gym. In short, VO2 is essentially your bodys ability to use oxygen.
Regarding weight training,studies show that those who have a higher VO2 max burn more fat from exercise.
So it makes sense that fasted training can help you burn more fat by increasing your VO2 max.
Fasting For Healthy Weight Loss The Wrap Up
Intermittent fasting can play a role in your healthy weight loss lifestyle.
But remember, fasting is not a magic bullet. The rest of your diet and lifestyle still matter.
Also, remember our six tips for healthy weight loss with intermittent fasting:
If you follow these tips, theres a good chance that intermittent fasting can help you lose weight in a healthy way.
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Only Do Heavy Lifting After A Meal
Not only heavy lifting but also other forms of high-intensity activities such as HIIT training and CrossFit require high amounts of energy, so its best to have some carbs in your system beforehand.
Make sure you eat properly before you try any of these activities so that you can keep a good performance throughout your workout!
Effect Of Ramadan Fasting On Lbm Body Weight And Fat
Trabelsi and colleagues published two studies investigating Ramadan fasting in conjunction with resistance training four times per week in recreational bodybuilders . In both studies, the fasting groups demonstrated no significant change in LBM, body weight, body fat mass, and body fat percentage . In the 2012 study , Trabelsi incorporated a non-fasting habitual diet control group. Compared to the Ramadan fasters, the control group demonstrated a significant increase in body weight , with non-significant increases in both fat mass and LBM. In the 2013 study , a strength of the study design was that authors controlled for diet prior to exercise, in order to determine if exercising in a fasted versus non-fasted, fed state influenced changes in body composition. Similar changes in body composition were observed for both the fasted and fed exercise groups.
The study by Stannard et al. found that recreationally active males undertaking two to five sessions of weight-training gymnasium exercise, in conjunction with Ramadan fasting, resulted in no significant changes in LBM, despite an average body weight loss of 1.3 kg and a 0.7 kg reduction in fat mass .
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How To Intermittent Fastwhat Should I Eat Or Drink While Fasting
Obviously, you don’t eat anything during your fasting hoursâno food or shakes. Water, of course, is fine. Otherwise, opt for zero-calorie, unsweetened beverages.
Calorie-free drinks with artificial sweeteners , can be problematic. There’s evidence that some artificial sweeteners cause an insulin response, which would blunt your ability to burn fat and contradict the point of being in a fasted state, but that’s up for debate in the scientific community.
If you’re absolutely dying for something other than water or plain coffee or tea during the last few hours, opt for a sparkling water that’s very lightly flavored with something like natural lime.
One Downside Of If: Loss Of Lean Muscle Mass
While weight loss for cardiometabolic health is a sensible goal, weight loss from any intervention often entails a concurrent loss of lean muscle mass. This has been a notable finding what I might even call an adverse side effect of intermittent fasting protocols. Given the importance of lean muscle mass for revving your metabolic rate, regulating your blood sugar, and keeping you physically able overall, pairing resistance training with an intermittent fasting protocol is strongly advised.
Finally, the weight loss achieved through time-restricted eating is likely different than the cellular adaptations that happen with more prolonged fully fasted states. At this time, it is hard to determine the degree to which the cardiometabolic benefits of fasting derive from weight loss or from underlying cellular adaptations it is likely an interrelated combination of both.
Nevertheless, it seems clear that in a 24/7 world of around-the-clock eating opportunities, all of us could benefit from aligning with our circadian biology, and spend a bit less time in a fed state and more time in a fasted state each day.
About the Author
Richard Joseph, MD, Contributor
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What Is A Fasted Workout
A fasted workout is a workout you do in a fasted state . When fasted, your body has had time to digest and metabolize a good proportion of what you ate at your last meal. That means your body’s fuel preference will change from glucose to fat.
You might fast before weight training or running as a specific training or weight-loss strategy. It is also relevant for those who fast for religious purposes, those who practice intermittent fasting, and those who need to fast for particular periods of time for medical reasons .
Hormones like insulin and glucagon change in relation to the amount of glucose in the blood and liver. When blood glucose is high, the body uses glucose for fuel. Glucose comes from all of the macronutrients, but mostly from carbohydrates. When blood glucose levels subside, the body burns fat to preserve the glucose stored in muscle and the liver. This helps maintain an optimum blood glucose level.
Fasted weight training aims to take advantage of the way the body burns fuel for energy in order to optimize the amount of fat burned during an exercise session. Some believe you can burn more fat by exercising on an empty stomach. Others believe that some pre-workout nutrition makes your weight training session more effective because your body has more energy.
