Running, burning fat, exercise Running on an empty. Image: Unsplash
Running on an empty stomach, often referred to as fasted cardio, can be a touchy subject among fitness experts and enthusiasts. In a recent interview, Pushpa 2 actor Allu Arjun revealed that his fitness routine consists of a 45 minute to an hour long run on an empty stomach.
The premise is simple: by exercising before breakfast or after a prolonged fasting period, your body taps into stored fat for fuel instead of relying on the readily available glycogen.
Sounds like an ideal solution to weight loss, right? Here’s the catch. While this approach can help burn fat, the scale doesn’t always tip in your favour as quickly as you’d hope.
Running on an empty stomach may accelerate fat metabolism during the workout, but here’s the kicker—your body’s primary concern is survival, not aesthetics. It adapts by conserving energy after your run, potentially reducing calorie burn throughout the rest of your day. So, while it’s a handy tool for burning fat, it’s not a magic solution for shedding kilos overnight.
Truth be told, the answer to this question comes down to personal preference. For morning people who feel light and energetic before eating, fasted exercise can feel like a natural extension of their routine. But for others, skipping breakfast before a workout may lead to dizziness, reduced performance, or that dreaded mid-run slump.
Scientific studies show mixed results. According to a 2018 study published by Cambridge University Press, exercising on an empty stomach versus after eating may affect metabolism differently and could potentially impact the body's long-term response to exercise for health benefits.
If this proves true, guidance on the timing of exercise relative to eating could be included in general fitness recommendations or tailored to specific groups aiming to maximise health or therapeutic outcomes. However, more research is needed to determine whether exercising on an empty stomach is truly better.
Fasted cardio may be effective for fat-burning during the workout, but it doesn’t necessarily lead to greater weight loss over time compared to exercising in a fed state, as celebrity fitness trainer and founder of Boxx Era, Jeeth Sanghavi, points out. “If you’re looking for weight loss, you can try exercising on an empty stomach, but if you’re aiming for sustainable fat loss, it’s better to avoid it,” says Sanghavi, adding: “When you work out on an empty stomach, you’re more likely to lose muscle mass. However, if you have a balanced meal containing protein and carbs before your workout, you’ll burn fat, not just weight, while maintaining lean muscle.”
Weight loss boils down to the classic calorie deficit equation—burning more calories than you consume. Running fasted can be a useful strategy for some, but it’s not the be-all and end-all. Your total daily energy expenditure, diet, and exercise consistency are the heavy lifters in the weight loss game.
One potential downside to fasted running is the risk of burning through muscle for energy. If you’re not careful, your body may dip into protein stores to fuel your workout, which could sabotage your long-term fitness goals.
“If you want to lose muscle and just appear slimmer in clothes without much muscle definition, you can try exercising on an empty stomach,” says Sanghavi, who helped actress Priyanka Chopra get the physicality of an Olympic boxer for her role in the biopic Mary Kom.
“However, if you’re aiming for fat loss and a toned, athletic physique like a sprinter, never work out on an empty stomach. There’s a big difference between weight loss and fat loss. You can lose weight and still not feel confident when you take your clothes off, but training with proper nutrition will help you achieve a defined, lean look,” she explains.
While fasted cardio, like running or cycling, can help burn fat, strength training is a whole different story. Lifting weights requires glycogen for energy bursts, and without proper fuel, your performance can take a hit, making it harder to lift heavy or sustain intense sessions.
“Both strength training and cardio should ideally not be done on an empty stomach,” says Sanghavi. “While fasted workouts might show quick weight loss on the scale, they also lead to muscle loss, which is hard to rebuild and maintain. Long-term side effects of fasted training include saggy skin, reduced muscle definition, premature aging, and a slimmer—but not toned—appearance. Balanced nutrition and training are essential for sustainable results and a sculpted, healthy body.”
Sanghavi also reflects on personal experience: “When I was a professional athlete, I tried fasted workouts 20 years ago. Not only did I lose muscle, but I also suffered severe injuries. Muscle loss weakens bones, leading to harder recoveries.
While some people swear by fasted training, it often causes muscle breakdown as the body uses muscle tissue for energy instead of burning fat. This decreases strength and endurance, ultimately hindering progress in both cardio and strength training.”
For long-term and optimal results, Sanghavi believes that proper nutrition is the key. A balanced pre-workout meal with protein and carbs boosts energy, improves performance, and protects muscle. “This way, you’ll not only lose fat, but also develop a defined, toned physique with better muscle retention,” she concludes.
[Via GQ India]
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