It has been well understood that in order to achieve and maintain a healthy weight, one must reduce overall calorie consumption and increase calorie expenditure through physical activity. One pound of body weight equals 3500 calories (so to lose one pound a week, one must decrease food intake by 500 cals/day), but not all calories are created equal!
Get the Most Bang For Your Buck
When trying to lose or maintain weight, it is best to choose your calories wisely; this means that in order to get "more bang for your caloric buck", choose foods that will positively affect your health. If most of your calories come from fatty foods like red meat, sausage, fried foods, baked goods, and creamy dishes, then blood cholesterol levels tend to be higher, which in turn can lead to clogged arteries and other cardiovascular diseases. Consuming most of your calories from healthier sources like lean protein (beans, nuts, white meats), vegetables, fruits, low fat dairy, and whole grains will have a positive effect on cholesterol and blood sugar levels which leads to a steady release of energy and an overall feeling of wellness.
Another benefit of selecting healthier foods towards your daily calorie goal is that you will feel full (not hungry!) even while losing weight. Calories that come from sugary, refined foods like candy, white breads, sugary cereals, and white potatoes will cause a rapid increase in blood sugar levels followed by a surge of insulin to bring blood sugar levels back down. When blood sugar rises and falls at rapid rates, you tend to feel hungry more often and have less energy. On the other hand, a diet that is rich in whole grains, lean proteins, and healthy (unsaturated) fats will allow blood sugar levels to rise and fall at a steadier, more controlled pace, leaving you feeling satisfied between meals and more energetic.
Beware of dietary “UFOs”, or Unidentifiable Food-like Objects. This term refers to foods that are highly processed, contain many chemicals, and offer very little (if any) nutritional value for the calories they contain. Choosing whole foods that are closer to their natural state will help maximize the health benefits of the foods you are eating. The calories that come from whole, natural foods will help you in meeting your health goals and feeling the best you can.
image sources: http://www.ihearexercisewillkillyou.com/2013/05/peanut-free-chewy-granola-bars.html, http://www.myjewishlearning.com/blog/rabbis-without-borders/2013/02/, http://en.wikipedia.org/wiki/SnackWells, http://talesfromthelou.wordpress.com/2011/05/11/the-nasty-nine-food-additives-to-avoid/