Lounge
Should you exercise on an empty stomach?
Summary
Exercise on a full stomach or on an empty stomach? This age-old question has some very interesting answers. Lounge speaks with experts to find out
Early mornings and late evenings are the busiest periods in gyms. The easiest explanation is that people want to—and, at times, have to—workout either before or after a work day. The thing is, such preferences may not always depend on what is the best time for the body.
That said, mornings are particularly busy, with a lot of gyms now capping treadmill (or any other cardio machine) usage to 15 minutes so that everyone can sweat it out. My favourite window to workout is before lunch, but not everyone has that freedom. But this choice is not based on how the body feels, but on how the body is fuelled.
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There is a high chance that morning workout enthusiasts are also training in a fasted state, which means on an empty stomach. The logic being that when you are fasting, the lack of insulin levels in the body allows fat to be burnt more efficiently, leading to fat loss. However, it is important to understand exactly what science has to say about this.
“When insulin levels are high, studies show that fat burning is halted, which makes sense because your body recognizes there is energy available at the moment. This is called being in a postprandial, or fed, state. You are considered fasting once food has been completely digested, absorbed, and insulin is back as baseline and this normally occurs around 4 hours after consuming a meal," says Destiny Moody of the US-based nutrition and health company Top Nutrition Coaching. Moody is a dietician who specialises in sports performance, body composition changes and injury recovery.
Given that fat loss is one of the primary goals that motivates people to get into fitness, working out in a fasted state sounds like a great idea. However, like every too-good-to-be-true ideas in the gym, this approach has its limitations and might not be for everyone. When one is chasing fat loss, it is mostly fat around the belly that they want to burn.
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Moody cites research published in the Journal Of Applied Physiologytitled Use Of Intramuscular Triacylglycerol As A Substrate Source During Exercise In Humans.The paper suggests that most of the fat burnt while working out in a fasted state is intramuscular fat and not the subcutaneous fat around the belly.
Then there is the risk of muscle breakdown if you attempt strength training in a fasted state. “It is generally not recommended to do strength training or weight lifting while fasted, as studies have shown that this practice significantly increases the rate of muscle breakdown in the body, which is the opposite of what you’re trying to achieve with strength training," says Moody.
But what about cardio? For a study published in 2014 in the Journal Of The International Society Of Sports Nutrition, researchers observed 20 adults over four weeks as they trained in fasted and fed states, while on a caloric deficit. Both groups lost weight and the research concluded that “body composition changes associated with aerobic exercise in conjunction with a hypocaloric diet are similar regardless of whether or not an individual is fasted prior to training." The paper is titled Body Composition Changes Associated With Fasted Versus Non-Fasted Aerobic Exercise.
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Tim Dileo, who works with elite athletes and is one of Top Nutrition Coaching’s experts, says that fasted workouts might mean nothing unless one is an endurance athlete at the top level. “No, there are not enough standout advantages of working out in a fasted state to try it," he says, while explaining how it could lead the body to improve fat oxidation. However, this is not an exclusive advantage. There are other strategies that achieve the same results.
I have tried to exercise in a fasted state and simply could not push my body the way I can in a fed state. But it comes down to how your body feels. If you still want to try this, then Dileo suggests a couple of pointers. “Start with low to moderate intensity exercise. These types of exercise rely more heavily on fat being used as a fuel source compared to high intensity training which relies mostly on carbohydrates. After the workout, you should refuel with a balanced recovery meal containing proteins, carbs and healthy fats, such as a veggie omelette with avocado toast." He also adds that mornings are the best time to try this as muscle glycogen stores will be lower post sleep.
Ultimately, it comes down to how you feel when you enter the gym. If a fasted state workout means you enter and leave in a groggy and not-confident way, you need to change the fuelling times for the body. But if fasted state workouts have given you better results than other strategies, keep at it, while knowing that at some point, you might have to increase the intensity to keep those results steady.
Pulasta Dhar is a football commentator, podcaster and writer.
