RRI.CO.ID, Jakarta - Working out on an empty stomach, also called fasted exercise, is popular for people who exercise first thing in the morning. Many say it helps burn more fat and boosts results. The idea is simple: after not eating all night, your body has less fuel from food, so it uses stored fat for energy during exercise. Insulin levels drop overnight, which makes this process easier.

When you exercise after 8 to 12 hours without food, your body works differently than after a meal. Insulin is lower, and your liver has used some of its stored carbs called glycogen. With less glycogen, your blood sugar drops more easily during exercise. This makes your body rely more on fat for energy. Hormones like adrenaline also increase, which helps release fat from storage to use as fuel.

The main benefit of fasted workouts is that they increase fat burning during the workout itself. When insulin is low, your body breaks down fat faster for energy. Think of it like using two fuel tanks: food is the first tank, and body fat is the backup. Fasted exercise drains the first tank quickly, so your body switches to fat sooner.

However, burning more fat during exercise doesn’t always mean you lose more body fat overall. Your body may burn less fat later or make you feel hungrier, so total fat loss depends on your calories for the whole day. Research shows there’s no big difference in long-term fat loss between fasted and fed workouts if your diet stays the same. You can’t out-exercise a bad diet.

Fasted workouts can work well for some people but not for others. They may help people who are new to exercise or have insulin resistance. But for trained athletes, exercising without food can lower performance and slow recovery. High-intensity workouts, long runs, and heavy lifting usually need carbs for energy, so eating beforehand is better.

Some people should be careful with fasted exercise. If you have diabetes or take medicine that lowers blood sugar, fasting plus exercise can cause dangerously low blood sugar. People with a history of disordered eating or low energy may also be harmed. Most studies on this topic are short and done on young men, so we still need more research on women, older adults, and people with health conditions.

If you want to try fasted workouts, keep it simple and safe. Short, easy workouts are fine without food. For longer or harder workouts, eat first. Drink water, and eat soon after to refuel your body. Pay attention to how you feel—if you feel dizzy, tired, or irritable, fasted training might not be right for you. In the end, the most important things are exercising regularly, doing it safely, and eating in a way that supports your goals.

Source: Nat Geo