You’ve probably heard a lot about your metabolism — what it does, why it slows and the role it plays in determining your weight. Some of the information may have been factual, and some may be mere marketing fiction, especially when it comes to weight-loss supplements.
According to Erin Peisach, RDN, a wellness education specialist with Sharp Rees-Stealy, metabolism is the process by which our body converts the foods we eat and drink into fuel for the body’s basic functions. While many believe that most of this fuel is burned through exercise, only 20% of your energy is used to fuel muscles during everyday activities and exercise. The majority of the body’s energy is used to fuel vital organs and digest food.
Peisach recently answered these four common questions about metabolism.
1. What determines the speed of our metabolism?
Metabolism and lean body mass are closely linked. Individuals with more lean body mass (muscle) than adipose (fat) tend to have a faster metabolism, meaning they use more energy to support body processes. Physiologically, men tend to have a higher proportion of lean body mass compared to women, explaining why they usually have a faster metabolism.
As individuals age, adipose often replaces lean body mass. Fat cells require less energy than muscle cells, resulting in a slower metabolism. Extreme dieting may also lead to a slowed metabolism. When the body undergoes energy deprivation, such as with long-term adherence to very low-calorie diets, the body goes into “starvation mode.” Essentially, the body adapts to this decreased calorie intake by burning less energy to sustain normal functioning. This often results in a weight-loss plateau or some weight regain as soon as the diet ends.
2. What is your basal metabolic rate, and how is it calculated?
Your basal metabolic rate (BMR) is the rate at which your body uses energy while at rest to maintain your basic vital functions, such as breathing, keeping your heart beating, and warming your body. Simply put, this is the amount of calories your body needs just to stay alive. Knowing your BMR can help you better estimate your body’s basic calorie needs to reach or maintain a desired weight and achieve a healthy body mass index (BMI), a measurement of your weight in relation to your height.
There are many equations for estimating your BMR. Metabolic testing, which involves a method called indirect calorimetry, is performed in a clinical setting and will provide the most accurate estimates.
3. How closely tied are one’s metabolism and weight?
Those with a higher than average metabolic rate are more likely to maintain a normal BMI throughout their lifetime. This should not discourage those with a slower than average metabolism from working to achieve a normal BMI. However, they will often have to pay closer attention to their food choices, calorie intake and physical activity to do so. In general, eating fewer calories than your body needs to both perform basic functions and fuel any exercise and additional activity you do can result in weight loss.
4. Do products that claim to speed up your metabolism work?
Supplements touting weight loss and increased metabolism have little or no benefit, and may have serious side effects, such as heart attack. They are not regulated like pharmaceutical drugs, the ingredients are not usually rigorously tested for safety or authenticity, and they do not require review or approval before being sold to the public.
Furthermore, although some studies have suggested that “super foods,” such as green tea and chili pepper, may increase metabolism, the effects are weak, short-lived and unlikely to contribute to overall weight loss. Essentially, these products are not likely the “magic pill” you may hope for.
Talk with your doctor if you are concerned about your metabolic rate or BMI. Together you can assess your food choices, calorie intake and physical activity, and make a plan to improve your overall health and wellness.
Learn more about Sharp Rees-Stealy’s metabolic testing, dietitian consultations and health management programs.