Debbie J., MS, RD contributed this article –
Energy is important to your health, and balancing it with physical activity is essential to achieving or maintaining a desirable weight. The almighty calorie we see on food labels is actually a “kilocalorie” by scientific terms, defining a specific amount of energy. Some countries use the term “joules” as an energy unit. Either way, it describes the amount of fuel derived from our food, or more accurately the carbohydrate, fat, protein and alcohol within. Vitamins, minerals, fiber and water provide no energy.
Why it matters that you only get the calories you need…
Without sufficient calories to meet our basic energy requirements we feel hungry and lethargic as we draw on stored energy from glycogen and fat and our metabolism slows down to conserve it. Too many calories on a regular basis can cause fat cells to grow and accumulate. Energy balance is achieved when you are eating as much as you burn which should keep your weight stable.
Most adults need 2000-2400 calories for daily needs excluding the amount needed to exercise. Guidelines for how many calories you should be eating in a day are primarily based on your gender, age, height, weight and activity level. Genetics, lean body mass and previous weight loss attempts also play a huge roll in your metabolism, making your personal energy equation unique.
For intentional weight loss, a modest reduction in dietary intake combined with increased physical activity means that your cellular metabolism is stimulated and basic requirements are still met. For most people a 300-500 calorie per day reduction from their usual intake will result in weight loss.