"Those with smaller body frames, who are shorter and may have difficulty holding on to muscle mass, tend to have lower metabolisms," Dr. Lowden told POPSUGAR. How can you tell if that's you? Get your metabolism tested, Dr. Lofton said. You can do this at weight management centres as well as some gyms and dietitians' offices, and you have a few different options to choose from.
The first is called indirect calorimetry, which determines your metabolic rate by measuring your oxygen consumption and carbon dioxide production. The second option is bioelectric impedance, which measures your fat mass, muscle mass, and water percentage — and from those, your metabolism — by way of a painless electrical impulse that passes through your body.
If neither testing option is available to you, Dr. Lofton said, you can also get a rough estimate of your metabolic rate from an online calculator. "Keep in mind that these only base off height and weight, and will have some error depending on one's fat mass," Dr. Lofton cautioned. Here are a few other ways to determine if you have a slow metabolism.