Abnormal basal metabolic rate

Abnormal Basal Metabolic Rate (BMR) refers to any deviation from the normal range of the basal metabolic rate, which is the amount of energy expended while at rest in a neutrally temperate environment, in the post-absorptive state (meaning that the digestive system is inactive, which requires about 12 hours of fasting in humans). The BMR affects the rate at which a person burns calories and ultimately, their energy balance and weight. An abnormal BMR can indicate various health issues, ranging from metabolic disorders to hormonal imbalances.

Overview

The basal metabolic rate accounts for the largest portion of the total energy expenditure by the body in a day. It is influenced by several factors including age, sex, body composition, and genetics. An abnormal BMR can lead to or be a sign of nutritional deficiencies, endocrine disorders such as hypothyroidism or hyperthyroidism, and other metabolic conditions.

Causes

Hypothyroidism and hyperthyroidism are among the primary causes of an abnormal BMR. Hypothyroidism leads to a lower-than-normal BMR, while hyperthyroidism causes a higher-than-normal BMR. Other factors that can cause an abnormal BMR include:

• Genetic predispositions
• Malnutrition or poor diet
• Obesity
• Eating disorders such as anorexia nervosa or bulimia
• Prolonged stress or illness
• Sedentary lifestyle

Symptoms

Symptoms of an abnormal BMR depend on whether the BMR is higher or lower than normal. Symptoms of a high BMR include:

• Weight loss
• Insomnia
• Increased appetite
• Anxiety and nervousness
• Increased heart rate and blood pressure

Symptoms of a low BMR include:

• Weight gain
• Fatigue
• Decreased appetite
• Sensitivity to cold
• Depression

Diagnosis

Diagnosing an abnormal BMR typically involves measuring the BMR using indirect calorimetry, which estimates the energy expenditure by measuring the oxygen and carbon dioxide exchange. This test is often complemented by blood tests to check for levels of thyroid hormones, which are closely linked to metabolic rate.

Treatment

Treatment for an abnormal BMR focuses on addressing the underlying cause. For hypothyroidism, thyroid hormone replacement therapy is commonly prescribed. For hyperthyroidism, treatment may include antithyroid medications, radioactive iodine therapy, or surgery. Lifestyle changes, such as diet and exercise modifications, are also recommended to help manage BMR.

Prevention

Preventing an abnormal BMR involves maintaining a healthy lifestyle, including regular physical activity, a balanced diet, and managing stress. Regular check-ups with a healthcare provider can also help detect and treat conditions that may affect BMR early on.