You need to use a calorie calculator to find your calorie goals for your height, weight, age and activity levels. This is the most important when it comes to hitting goals for weight loss, weight gains or even maintaining the weight. This is where most people go wrong when trying to lose weight is under eating. A Lot can happen if you are not taking in the right amount of calories definitely under eating. Will be lacking the protein the body needs. That is why a lot of people will lose hair when cutting calories. Can slow down the metabolism, hormone changes which hormones play a big role in living a healthy life. So be sure to use the calorie calculator here on the site.