A person's basal metabolic rate refers to the number of calories his or her body burns while at rest. The human body needs some calories simply to breathe, pump blood, and maintain body temperature. It represents the minimum number of calories an individual needs to survive in the absence of any activity. Literally, basal metabolic rate represents the quantity of calories needed just to stay in bed and sleep all day.
The higher a person's basal metabolic rate, the more calories that individual burns off without engaging in any physical activity. Basal metabolic rate may vary significantly from one person to another. An individual's basal metabolic rate is partially grounded in genetics. Men typically have a higher basal metabolic rate than women, because they tend to naturally have both a greater muscle mass and a lower percentage of body fat.
Hormonal factors can also impact basal metabolic rate. Thyroxin, which is produced by the thyroid gland, is a very important factor in basal metabolic rate. If a person does not produce a sufficient quantity of thyroxin, his or her basal metabolic rate will slow. If too much thyroxin is produced, basal metabolic rate can increase by as much as 100 percent. This is the reason that untreated thyroid problems can lead to extreme weight fluctuations. Fortunately, thyroxin imbalances can be controlled by medication for most people.
Additionally, regardless of gender or other genetic factors, some people naturally have slower metabolisms, and others have higher basal metabolic rates. In addition to the impact of hereditary factors, basal metabolic rate also can change significantly with age and/or activity level. Generally speaking, the more lean body mass a person has, the higher his or her basal metabolic rate. Conversely, as body fat percentage increases, basal metabolic rate decreases.
One of the reasons that cardiovascular exercise and weight training play such an important role in weight loss is that these two activities can increase basal metabolic rate. The reason that people have a tendency to gain weight as they age if their exercise levels do not increase, is that basal metabolic rate tends to decrease as they age and naturally begin to lose lean muscle mass. After the age of 20, basal metabolic rate tends to decrease by about two percent each year. If calorie consumption remains constant but exercise levels do not increase, weight gain will occur as basal metabolic rate declines with age.
Individuals who are overweight or obese have a high risk for chronic conditions such as high blood pressure, diabetes, and high cholesterol. A person that is overweight should try to avoid gaining additional weight and increase their daily activity level. Additionally, if you are overweight with other risk factors (such as high LDL cholesterol, low HDL cholesterol, or high blood pressure), you should try to lose weight. Even a small weight loss (just 10% of your current weight) may help in lowering the risk of disease. In order to lose weight, you simply need to increase your daily activity or consume fewer calories than those needed to maintain your weight.