Food intake and physical activity is a debatable topic. Some research argues that there are benefits to working out on an empty stomach, while other evidence argues that the negative effects can outweigh the benefits. Fat burn can increase if you workout on an empty stomach, but you also risk using muscles for fuel and limiting your training duration due to fatigue. Get the facts, then consult a professional concerning the best approach for your condition. Here are the facts we found.

The Early Bird Gets the Burn

fat-burn workout

A study found that working out on an empty stomach can increase fat burn. The researchers took 28 healthy persons and had them eat a diet with 50% more fat and 30% more calories than their regular diets. Some of the people abstained from training, while the others were instructed to workout 4 times a week in the mornings. Some of the men ate breakfast before exercising while others didn’t.

At the end of the study, the people skipping breakfast before workout gained less weight and encountered improvements in insulin sensitivity than the ones who ate before exercising.

Intensity is Crucial

workout intensity

Working out on an empty stomach can be most effective when doing steady-state cardio. Nevertheless, high-intensity exercises such as heavy resistance training rely generally on glucose for muscle contraction. If glucose supplies are low after few hours of fasting, your body can break down your lean muscle mass for fuel, overpowering the purpose of your training. Your workout status, stores of intramuscular fat and the scope of your muscles to store glucose in the form of glycogen are the primary determinants of energy pathways during intense training.

Brain Drain

brain drain

Exercising on an empty stomach can result in low blood glucose, which may interfere with your brain function. When eating, the glucose levels in your circulating blood rise and are ready to travel to your muscle cells. Glucose is available as glycogen stored in your muscles.

If you workout on an empty stomach, glycogen and blood glucose may become quickly depleted, causing hypoglycemia. Because our brain runs exclusively on glucose, low levels can cause light-headedness, nausea, poor exercise performance, and muscle fatigue. Regular ongoing workout enhances your muscles’ capability to store glycogen.

Plan for Performance

Quantity and timing of food can influence your training performance. For optimal training capacity, follow these guidelines:

  • If you eat a big meal, wait for 3 to 4 hours before a workout.
  • For a small meal, eat 2 or 3 hours pre-workout.
  • A snack is your best option, eaten 1 hour before workout.
  • Consume a piece of fruit, yogurt or granola bar before a workout to maximize blood glucose and calorie burn.
  • Eat a snack that combines protein and carbs immediately after a workout. It will replenish muscle glycogen stores, preparing you for your next workout.
  • Hydration and replacement of electrolytes are critical for peak workout performance.


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