Many people are interested in speeding up their metabolism in an effort to lose weight. There are drugs, supplements, and even certain foods that are thought to increase metabolism. The effectiveness of many of these things is unproven and some may actually be dangerous. The goal of this article, and my Health & Fitness column in the Aiken Standard this week, is to explain what the term “metabolism” really means and how it can be changed.
Metabolism refers all of your body’s processes that expend energy, or burn calories. Practically, this is how much carbohydrate, fat, and protein is burned throughout the day to provide energy for your cells. This matters because if expending more energy than you consume in your diet can lead to weight loss over time.
The amount of energy you expend in a day is composed of three main components: your resting metabolic rate (RMR), something called the thermic effect of food (TEF), and the energy you expend in activity.
Resting metabolic rate (RMR) is sometimes called the basal metabolic rate (BMR), but many people refer to it as their “metabolism.” No matter which name is used, it refers to the calories you burn at rest. It represents the energy needed to maintain your essential body functions: heart rate, breathing, body temperature, and normal cellular processes.
The RMR is important because it represents about 60–70% of the total calories a typical person burns in a typical day. Even though RMR is important, you shouldn’t worry about it too much.
First, it is difficult to change. RMR is based mostly on your lean body mass, so the only way to increase it is to gain muscle mass. While this is a good goal, it is challenging to do, especially while you trying to losing weight.
Second, although it does vary among people, it isn’t as different as people like to think. It is easy to think that someone who gains weight has a “slow metabolism” or that someone who is thin must have a “fast metabolism.” In reality, the RMR probably isn’t much different, certainly when you take lean body mass (muscle) into account. The explanation for the differences in weight among people probably has more to do with what they eat and how active they are.
The thermic effect of food (TEF) represents the energy needed to digest, absorb, and store the nutrients you eat. It accounts for only about 10% of your total energy expenditure and it is practically impossible to change, so you can ignore it.
Activity is the most variable component of energy expenditure and the one you can most readily change. Obviously, it will depend on how active you are, but for most people it accounts for 20–30% of total energy expenditure.
Activity includes both purposeful movement such as exercise and doing work or tasks that require you to move. Activity also includes non-exercise activity thermogenesis or NEAT, the calories you burn when you move around, but not in a purposeful way. Maintaining your posture when sitting or standing, fidgeting in your chair, or other light movements count as NEAT.
The surest way for you to increase your metabolism is to limit the time you spend sitting, be active as possible at all times, and dedicate time to exercise every day. Doing prolonged aerobic exercise such as walking, jogging, or exercise classes directly burns calories and including strength training will help increase your muscle mass, which can increase up your RMR.
The bottom line is that speeding up your metabolism requires you to move. So, get up off the couch and go for a walk!