What is the difference between a calorie reduced diet and fasting?

When I was initially hearing about the benefits of fasting, I did wonder what the difference was between reducing your calories or the amount of food you are eating throughout the day versus having a shorter eating window in the day with intermittent fasting.

Here are the differences between a calorie restricted diet and fasting.

If you’re eating fewer calories you’re not getting the beneficial hormonal changes of fasting. During fasting, metabolism stabilizes or even goes up to maintain normal energy levels. Adrenaline and growth hormone increase to maintain energy and muscle mass. Blood sugar and insulin levels go down as body changes from burning sugar to burning fat. Overtime fasting reduces insulin levels more effectively than calorie restriction. 

The body adapts to changing environment. If you maintain a constant reduced-calorie diet, the body will quickly adapt to it. Energy expenditure (metabolism) declines to match the reduced intake. Weight plateaus then is regained. To prevent the body from adapting requires an intermittent strategy not a constant one.