As soon as you start eating, the process is halted. Insulin now inhibits the breakdown of fatty acids, leading your body to burn the sugars you've just ingested. The fat burning stage is over.
If you think about it, this all makes perfect evolutionary sense. When food wasnt as readily available as it is today, holding on to stored body fat was crucial for our survival. We evolved to last a long time between meals.
Today, food is in almost constant supply but our bodies are still physiologically the same as they were tens of thousands of years ago. If we eat all day, we never tap into our bodies natural ability to burn stored body fat for energy.
Studies demonstrate that a bout of aerobic exercise performed in the fasted as compared with non-fasted state increases the reliance on fat and subsequently reduces the reliance on carbohydrate as fuel during exercise, with several publications showing that fasted exercise oxidises (burns) around 20-30pcmore fat.
If you're exercising to lose weight, it's a no brainer.
See more here:
Why exercising on an empty stomach is the secret to weight loss - Telegraph.co.uk
