Your RMR is the rate at which your body uses energy just to keep its basic functions going when you’re at rest—circulation, breathing, and digestion. Most people are surprised to learn that 65 to 75 percent of our energy is expended this way, without counting what it takes to walk or talk or work, let alone actually exercises.
This is part of why people who try to lose weight by exercising more—without making dietary changes—typically get very little result for their trouble. Since up to three-quarters of our energy is expended without even moving, an exercise-only approach is dealing with a pretty small proportion of the overall calorie use anyway.
Of course, over time, a good exercise program will speed up the RMR as well, and then people start to see accelerated results in weight loss, but most folks get discouraged and give up long before that happens. People with a slow metabolic rate burn less energy overall, hence the weight gain, even if they’re not eating any more than the next guy.
Remember that we said that your RMR level can actually improve. Exercise will do it as you gain muscle, and so will weight loss itself, sometimes to a surprising degree. Using the new indirect calorimeters, we have often found that a patient’s RMR is higher after a 20-pound loss of fat mass than it was before she dropped that weight.
That’s a quantifiable improvement, and for a weight-loss patient who’s been struggling, that kind of numerical proof really helps them keep up the good work.
Causes of low metabolism
1. Diabetes or insulin resistance (pre-diabetic condition)?
2. Higher percentage of body fat?
3. Underactive thyroid function?
4. Loss of lean body mass, muscle with age or inactivity?
5. Genetics??If you think you have an unusual metabolism, it may be worth getting it tested, now that it’s possible to have that done easily and accurately. There’s no point in laboring against unseen obstacles.