to find food (and lower its me), is key to maintaining the bmr of the cells driven, otherwise, by starvation, to approaching zero; while at the same time a lower me diminishes the fmr/mpls of the organism. medical considerations a person's metabolism varies with their physical condition and activity. weight training can have a longer impact on metabolism than aerobic training, but there are no known mathematical formulas that can exactly predict the length and duration of a raised metabolism from trophic changes with anabolic neuromuscular training. a decrease in food intake will typically lower the metabolic rate as the body tries to conserve energy. researcher gary foster estimates that a very low calorie diet of fewer than 800 calories a day would reduce the metabolic rate by more than 10 percent. the metabolic rate can be affected by some drugs, such as antithyroid agents, drugs used to treat hyperthyroidism, such as propylthiouracil and methimazole, bring the metabolic rate down to normal and restore euthyroidism. some research has focused on developing antiobesity drugs to raise the metabolic rate, such as drugs to stimulate thermogenesis in skeletal muscle. the metabolic rate may be elevated in stress, illness, and diabetes. menopause may also affect metabolism. cardiovascular implications heart rate is determined by the medulla oblongata and part of the pons, two organs located inferior to the hypothalamus on the brain stem. heart rate is important for basal metabolic rate and resting metabolic rate because it drives the blood supply, stimulating the krebs cycle. during exercise that achieves the anaerobic threshold, it is possible to deliver substrates that are desired for optimal energy utilization. the anaerobic threshold is defined as the energy utilization level of heart rate exertion that occurs without oxygen during a standardized test with a specific protocol for accuracy of measurement, such as the bruce treadmill protocol (see metabolic equivalent of task). with four to six weeks of targeted training the body systems can adapt to a higher perfusion of mitochondrial density for increased oxygen availability for the krebs cycle, or tricarboxylic cycle, or the glycolytic cycle. this in turn leads to a lower resting heart rate, lower blood pressure, and increased resting or basal metabolic rate. by measuring heart rate we can then derive estimations of what level of substrate utilization is actually causing biochemical metabolism in our bodies at rest or in activity. this in turn can help a person to maintain an appropriate level of consumption and utilization by studying a graphical representation of the anaerobic threshold. this can be confirmed by blood tests and gas analysis using either direct or indirect calorimetry to show the effect of substrate utilization. the measures of basal metabolic rate and resting metabolic rate are becoming essential tools for maintaining a healthy body weight.