When utilized correctly, intermittent fasting has been shown to be an effective strategy for building muscle & burning fat at the gym.
It’s a debate that’s raged since the first weight was lifted: Is it better or worse to work out on an empty stomach? Wars have been waged and nations have fallen (okay, that’s a slight exaggeration) during the eternal battle of fed versus fasted exercise, but it’s time for this madness to end. We have the final answer.
It’s time to dismantle some old myths about eating and exercise.
Well, not the final answer. Different people work out best under different circumstances, and deciding whether someoneshould eat before training can be like telling them what time of day to work out or which diet they should follow—it largely depends on what works best for the individual. But it is time to dismantle some old myths.
Contrary to popular belief, research suggests that eating many small meals throughout the day won’t speed up the metabolism, skipping a meal won’t make you fat, and exercising on an empty stomach will not nullify a workout. In fact, skipping a meal or two, also known as “intermittent fasting” (IF), can be downright beneficial.
Optimizing Hormones (Fast)
If the fact that “Huge Jacked-man” practiced intermittent fasting to gain muscle for his latest Wolverine movie isn’t convincing enough, consider this: An empty stomach triggers a cascade of hormonal changes throughout the body that are surprisingly conducive to both building muscle and burning fat.
An empty stomach triggers a cascade of hormonal changes throughout the body that are conducive to both building muscle and burning fat.
The fasted state produces two significant effects:
1. Improved insulin sensitivity. Put very simply, the body releases insulin (a hormone) when we eat to help us absorb the nutrients from our food. The hormone then takes the sugars out of our bloodstream and directs them to the liver, muscles, and fat cells to be used as energy later on. The trouble is that eating too much and too often can make us more resistant to insulin’s effects, and while poor insulin sensitivity ups the risk of heart disease and cancer, it also makes it harder to lose body fat . Eating less frequently (i.e. fasting more regularly) is one way to help remedy the issue, because it results in the body releasing insulin less often, so we become more sensitive to it—and that makes it easier to lose fat, improves blood flow to muscles, and even curbs the impact of an unhealthy diet .
2. The second reason a good old-fashioned fast can promote muscle gain and fat loss comes down to growth hormone (GH), a magical elixir of a hormone that helps the body make new muscle tissue, burn fat, and improve bone quality, physical function, and longevity . Along with regular weight training and proper sleep, fasting is one of the best ways to increase the body’s GH: One study showed that 24 hours without food increases the male body’s GH production by 2,000 freakin’percent, and 1,300 percent in women. The effect ends when the fast does, which is a compelling reason to fast regularly in order to keep muscle-friendly hormones at their highest levels.
We can’t speak of muscle-friendly hormones without bringing uptestosterone. Testosterone helps increase muscle mass and reduce body fat while also improving energy levels, boosting libido, and even combating depression and heart problems—in both men and women . Fasting alone may not have any effect on testosterone, but there is a surprisingly simple way to produce large amounts of both “T” and growth hormone at the same time, creating an optimal environment for building muscle and torching fat: Exercising while fasted .
The Fast Way to Improve Performance
Exercise, especially intense exercise that uses a lot of muscles (thinkcompound movements like deadlifts and squats) causes a big surge in testosterone—which is why it can make good sense to combine exercise and fasting . Many studies have found that training in a fasted state is a terrific way to build lean mass and boost insulin sensitivity, not just because of the nifty hormonal responses, but also because it makes the body absorb the post-workout meal more efficiently.
Many studies have found that training in a fasted state is a terrific way to build lean mass and boost insulin sensitivity.
In short, fasted training helps to ensure that carbs, protein, and fats go to the right places in the body and are stored only minimally as body fat . Exercising on an empty stomach has been shown to be especially great for fat loss, and it’s even been shown that people who train while fasted become progressively better at burning fat at higher levels of intensity (possibly because of an increase in fat-oxidizing enzymes) .
Not interested in training like a bodybuilder? There are also potential benefits for endurance athletes, since fasted workouts can improve muscle glycogen storage efficiency (say that three times fast!) . What that means, basically, is that running on empty can make the body better at using its energy stores. The occasional fasted training session can improve the quality of “fed” workouts (or races) later on. In a nutshell: When the body learns to exert itself without any food, it gets better at performing when it does have fuel in the tank. Some studies have also shown that fasted workouts can significantly improve endurance athletes’ VO2 Max, which measures a person’s capacity to take in and use oxygen during exercise and is a pretty decent way of measuring someone’s fitness.
When the body learns to exert itself without any food, it gets better at performing when it does have fuel in the tank.
Now, we would be remiss if we didn’t acknowledge that some studies have shown impaired performance as a result of fasted exercise. That said, many of these studies are of Ramadan fasts, which don’t allow the consumption of fluids (which is not advisable when engaging in athletic activities) . Still, the prevalence of people who do eat before exercise is pretty good evidence that exercising after eating can work. Heck, there are even studies showing that eating before exercise can lead to fewer calories consumed throughout the day . But that doesn’t discredit the evidence that fasted workouts, even if occasional, can reap a lot of benefits.