Fat not only serves as an energy source, especially effective over a longer distance. It is an important macronutrient that contributes to proper hormone regulation, pads internal organs, provides a source of energy and assists with absorption of specific vitamins.  A gram of fat has about

twice as many calories per gram as carbohydrates and proteins. We all need some fat in our diet. But Eating too much fat contributes to excess body weight, too much of a particular kind of fat – saturated fat – can raise our cholesterol, which increases the risk of heart disease.

It's true that a diet high in fat can lead to weight gain and heart disease. You must estimate how many calories you need in a day and count your daily fat intake.Note that this calculation of of fat you will need each day is just an estimate.