The secret to permanent weight loss is training your body to be a more efficient calorie-burning engine by maximizing your metabolism. Metabolism is the rate at which a person burns energy, and this is measured in calories.
There are three parts of metabolism:
The Resting Metabolic Rate (RMR) is the amount of energy required to maintain the bodily functions and processes when you are resting and awake. Your RMR comprises about 60% of your total daily caloric needs.
The Thermic Effect of Feeding (TEF) is the amount of calories you use to eat and digest food and makes up about 5-10% of total calorie needs.
The Thermic Effect of Activity (TEA) is the rate at which you burn calories while exercising and with normal movements. This accounts for about 30% of caloric needs. Unfortunately, as we age, our metabolic rate slows down. Starting at about age 25, the average and not physically active person's metabolism declines between 5% and 10% per decade, which accumulates to between 20% and 40% metabolism over the adult life span. However, there is good news for those who continue physical activity their whole lives: they have only a 0.3% metabolic decline per decade.
Boosting Your Metabolism
The most effective way to "boost" your metabolism is through exercise, especially if you are dieting. Cardio training and weight lifting exercise provides a protective effect against a drop in metabolism. This is because people tend to lose a considerable portion of muscle in calorie-reduction programs that don't include strength training, whereas one of the main benefits from exercise in weight loss programs is the preservation of muscle.
When you increase your muscle, you boost your resting metabolic rate. Weightlifting consumes calories, raises your metabolism, and builds muscle that will consume extra calories later on. This means that all other things being equal, your body will burn more calories even when you are doing nothing. Hunter (2000) did a study in which subjects did resistance training. After 6 months, subjects had increased their RMR and were burning an extra 100 calories per day.
Cardio also boosts metabolism. In a study, participants who did moderate intensity cardio exercise 3-5 days per week for 20-45 minutes for 16 months and had an average increase in RMR of 129 calories per day. (Potteiger 2008).