What Is Metabolic Rate?
Metabolism includes all the chemical reactions that occur in the body to maintain a balance. Metabolism is the combination of various functions in your body. The rate at which these processes occur is termed your metabolic rate. The food you eat is broken down and converted into energy. The breakdown of nutrients present in food and the formation of useful products for energy is metabolism. Your body breaks down nutrients into food and converts them into energy or heat. The extra nutrients are stored as fat for later use.
Metabolism is broadly categorized into:
1. Anabolism - the body utilizes the energy from nutrient breakdown to form complex molecules needed for daily functioning
2. Catabolism - the breakdown of food components or nutrients into simpler form to produce the energy needed for daily functioning
Some people have a faster metabolism than others. It varies from person to person, depending on a lot of factors.
Resting Metabolic Rate, or RMR for short, is the rate at which your body burns energy when at rest. Knowing your RMR will help you understand the energy needed by your body to perform basic life-sustaining functions like breathing, circulating blood, nutrient processing, cell growth, and functioning.
Basal Metabolic Rate (BMR) and RMR are slightly different. BMR is the minimum rate at which your body burns just enough calories to exist. RMR is a good estimate of your BMR.
By knowing your metabolic rate, you understand how many calories you burn and what your calorie intake needs to be to remain fit. It can help you devise a diet and exercise plan to remain healthy, stay fit and perform better.
Metabolic Rate and Exercise
Exercise helps you maintain weight and also can help change your metabolic rate. By building muscle through exercise, you can increase your BMR. The more intense your workout is, the longer your body takes to recover, the metabolism will increase more.
Exercises that increase muscle mass can help increase the resting metabolic rate also. The effect of exercise on metabolic rate increases with an increase in the intensity of the training.
The BMR of an average man is around 7,100 kJ per day, while that of a woman is 5,900 kJ per day. The expenditure of energy is continuous during the day; the rate varies and is found to be at its lowest early in the morning.
Estimating Metabolic Rate
BMR is usually estimated through the Harris-Benedict formula revised in 1990. The formula is gender-specific. You can calculate it on your own. All you need is your weight, height, age, and a little bit of math. The formula is given below.
Women
BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) - 161
Men
BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) + 5
How Does Genetics Influence Metabolic Rate?
UCP1 Gene
The UCP1gene encodes the uncoupling protein, which plays a role in generating heat by allowing fast substrate oxidation and lower ATP production in brown adipose tissue. It is responsible for adaptation to cold climates. Variants in this gene are associated with metabolism.
*rs1800592 *
rs1800592 is an SNP found in the UCP1 gene. The A allele is associated with a higher metabolic rate and slower weight gain compared to the G allele.
GPR158 Gene
The GPR158 gene encodes a protein called G-protein coupled receptor 158, which is highly expressed in the brain. It is known to influence the risk of obesity in mice. Variants in this gene are found to be associated with energy expenditure.
rs11014566
rs11014566 is an SNP in the GPR158 gene. People with the GG genotype were found to have lower energy expenditure, higher BMI, and higher fat mass compared to people with the AA genotype. This is seen in American Indians.
Non-Genetic Factors That Affect Metabolic Rate
A number of factors other than genetics influences metabolic rate. These include
- Age: Metabolism decreases with age due to gain in fat, loss of muscle, and decrease in physical activity. This means that the metabolic rate will also decrease with age.
- Gender: Generally, men have a faster metabolism than women because they tend to have more lean body mass and testosterone and lesser estrogen.
- Drugs: Nicotine and caffeine tend to increase metabolic rate.
- Body composition: Larger people tend to have a higher RMR. People with more lean muscle tissue and lesser fat have a higher RMR.
- Diet: A balanced diet can help you achieve optimal RMR. Fasting, starving, or crash dieting leads to loss of lean muscle mass and a decrease in RMR.
- Body temperature: Increase in body temperature increases RMR.
- Physical activity: Exercise done regularly increases muscle mass and can increase your RMR also.
Boosting Your Metabolic Rate
Working out can help you stay fit and healthy and increase your metabolism, thereby increasing the resting metabolic rate. Here are a few things that you can do to increase metabolic rate:
- Include plenty of proteins in your meal. It leads to a rise in the thermic effect of food, which is the extra calories needed to digest and absorb the nutrients in food. It also prevents muscle loss due to dieting and increases your metabolism.
- HIIT (High-Intensity Interval Training) workouts involve quick and intense energy bursts. Research shows that it helps boost metabolic rate after training.
- Lifting weights helps build and maintain muscle mass and increase metabolic rate. It also helps combat the drop in metabolism that occurs after weight loss.
- According to a review, resistance training can reduce fat mass and improve lean body mass, resulting in an increase in basal metabolic rate.
- Make sure you get adequate sleep. Sleep deprivation has negative effects on metabolism and is a risk factor for obesity.
- Research shows that drinking coffee can increase your metabolism and promote the burning of fats.
Summary
- Resting Metabolic Rate is the rate at which your body burns energy when at rest. Knowing your RMR will help you understand the energy needed by your body to perform basic life-sustaining functions like breathing, circulating blood, nutrient processing, cell growth, and functioning.
- Training and high-intensity workouts can boost your metabolism and metabolic rate. Exercise also increases muscle mass, which boosts metabolic rate.
- Variations in certain genes are found to affect metabolic rate. The AA genotype of SNP rs1800592 found in the UCP1 gene is associated with a higher metabolic rate and slower weight gain. The G allele of SNP rs11014566 found in the GPR158 gene is associated with lower energy expenditure.
- Non-genetic factors like age, gender, diet, body temperature, and body composition can lead to changes in your metabolic rate.
- Metabolic rate can be increased by increasing the intensity of exercise, lifting weights, resistance training, and eating a protein-packed meal.
References
https://www.healthline.com/health/what-is-basal-metabolic-rate
https://www.webmd.com/fitness-exercise/guide/how-to-boost-your-metabolism
https://pubmed.ncbi.nlm.nih.gov/2305711/
https://www.betterhealth.vic.gov.au/health/ConditionsAndTreatments/metabolism
