Start to Fitness: Metabolism affects weight-loss

Q: I exercise three times a week, but ever since I turned 40 years old I have had trouble losing weight. I believe my metabolism is the culprit. Could a slower metabolism be the reason I’m not losing weight, or might it be something else?

A: Metabolism is often blamed for weight gain or for difficulty in losing weight. Often it is assumed that slender people must have a fast or high metabolism, and that an overweight person has a slower or low metabolism. This is not necessarily true. In fact, the amount of energy or calories you expend in comparison to the amount of energy (calories) you consume is the true measure of how you lose, maintain or gain weight.

Metabolism is the process of converting food into energy. Calories from the carbohydrates, fats and proteins in the foods we eat are combined with oxygen to provide the energy our bodies require for everyday functions.

The amount of calories your body expends each day is affected by your body’s basal metabolic rate (BMR), how your body processes food and your activity level. BMR is your body’s calorie expenditure each day to support basic everyday functions, such as fuel for organs, cellular repair, breathing and circulation. The higher your basal metabolic rate, the more calories you burn each day.

A combination of the calories you consume compared to the calories you expend needs to be your focus toward losing weight.

The factors that determine how many calories you need, or don’t need, each day is determined by gender, age and overall body composition.

Males tend to have less body fat and more lean muscle than females, raising their BMR. This higher BMR can mean more calories are expended by just living each day. It does not mean that females are doomed to fail to lose weight; however, you should not compare your success based on gender. It also does not mean that males can rely on their BMR to maintain a healthy weight.

As we age, our metabolism gradually begins to slow down, requiring less calories to function. We also tend to lose lean muscle mass and develop more non-essential body fat, changing our body compositions as we get older. The more lean muscle, the more calorie expenditure throughout the day; the more body fat, the less calorie expenditure.

Although metabolism is not usually the cause of weight gain, you might talk with your physician about any medical changes to your body. Track how your body is responding to exercise and changes in weight over time, and present this information to your doctor.

It is important to remember that your daily activity level of cardiovascular and strength training plays a large role in weight management, and that over time, modifications to these regimes may be necessary. Continue to work hard, and remember that it will be easier to lose weight when you understand how your metabolism can work for you.