What happens to a person's metabolism when they consistently eat too little?

This is a very difficult question to answer without more information. We generally get this question from overweight people who think they are eating less than they really are. So our typical answer is: nothing happens to your metabolism and therefore if you need to lose weight and you are not, eat less and/or move more and forget about slowing your metabolism. That said the point is not to lose weight too fast by drastically reducing calories because first and foremost that method is miserable and generally not sustainable. Secondarily, there is a slight (fairly insignificant in the big picture) metabolism down regulation in response to a very low calorie diet – but – the main reason it may appear to slow down more than it actually does, is because it’s the very low calorie intake that is slowing YOU down. In other words you become tired forcing a reduction in your daily activities, causing you to move less thus burn fewer calories. Take home message: never blame failure on metabolism – no matter what anyone tells you! Used with permission by World Gym Express of Fairfax.