Amy Boone Thompson
Billions of dollars are spent each year on dieting plans and supplement aids to help people lose weight. Yet the obesity epidemic in America continues to steadily increase. Adults are consuming far more calories per day than needed. Factors such as bigger portions, convenience of fast food, higher caloric density food choices and limited access to nutritious foods are named in the blame. There is no question that adults need to take in fewer calories and choose healthier foods. A staggering two-thirds of American adults are obese and less than half of them meet the minimum recommendations for exercise. Just how important is exercise in the weight loss predicament? Can I restrict calories alone to reach my idea weight? To answer this question we need to first understand how the body’s energy equation works.
There are three primary ways that we use or “burn” calories. The resting metabolic rate (RMR) makes up about 75% of the total calories your body uses in a 24-hour cycle. The other 25% of caloric needs are for activity and digestion. RMR is the minimal caloric requirement needed. This is the amount of energy your body would burn if you slept for 24 hours. There are many factors that alter the RMR such as age, height, stress and hormone fluctuations, but body composition has the largest impact. Dr. Cheryl Rock, RD, Department of Family and Preventive Medicine at UCSD states, “The biggest contributor to total energy expenditure is the resting metabolic rate, or basal energy expenditure. The major determinant of RMR is the amount of lean body mass.”
To increase lean body mass a person needs to incorporate an exercise regime with cardiovascular activity and resistance training. “Exercise contributes to healthy weight control through two mechanisms – through increased total energy expenditure (because additional calories are burned doing the exercise) and also promoting the retention and increase in lean body mass (so that RMR is retained or increased).” says Rock. Just how much exercise is recommended? The Center for Disease Control & Prevention recommends 60-90 minutes of activity, daily. Sustained cardiovascular exercise should be gradually increased both in duration and intensity to this 60-90 minute range. Resistance training should be included 2-4 times per week addressing all major muscles. Consistency is the key to success in any exercise program.
Exercise benefits your body’s energy equation in two ways. Short-term- you burn calories while you do the activity. Long-term- you add lean body mass, which will increase the amount of calories your body requires at rest. This in turn helps you achieve a healthy weight faster, does not require you to starve yourself of nutrients and it allows you to enjoy life in a fully capable and mobile body.Center for Disease Control & Prevention, Prevalence of Physical Activity, Including Lifestyle Activities Among Adults — United States, 2000–2001, MMWR August 15, 2003, 52(32):764–769. Journal of the American Medical Association. 295(13):1549-55, 2006 Apr 5.