Metabolism is the process by which our body converts what we eat and drink into energy. During this complex biochemical process, calories in food and beverages are combined with oxygen to release the energy body needs to function.
Even at rest, our body needs energy for all its hidden or involuntary functions, such as breathing, circulating blood, adjusting hormone levels, and growing and repairing cells. The number of calories our body uses to carry out these basic functions is known as the basal metabolic rate (BMR) or resting energy expenditure (REE) .
In simple terms, the basal metabolic rate relates to the energy /calories a person burns while at rest . It’s the amount of energy your body needs just to keep you alive and perform basic functions like breathing, keeping your heart beating and maintaining your body’s tissues.
Depending on age and lifestyle, BMR represents 45 to 70 percent of daily total energy expenditure, and it is determined mainly by the individual’s age, gender, body size and body composition.
ENERGY INTAKE = ENERGY EXPENDITURE = BMR + PHYSICAL ACTIVITY + DIET INDUCED THERMOGENESIS
We observe that some people have higher metabolic rates than others which can be attributed to the difference in body composition. So there are mainly two compartments in the body:
- Fat Mass
- Fat free Mass or Muscle Mass or Lean body mass
|Muscle Mass / Fat free mass||Fat mass|
|Includes the total amount of nonfat (lean) parts of the body. It consists of approximately 73% water, 20% protein||Includes all the fat depots in the body|
|It is a metabolically active tissue||It is metabolically inactive|
|An individual having higher amounts of the lean body mass by birth or having acquired (strength training, etc) has higher BMR||Higher amounts of fat mass leads to slower BMR|
In the next part of this blog, we look at factors that affect BMR
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Dr Pooja Chhawcharia is the Senior Nutritionist at eKincare with over 7 years of experience in Nutrition education, diet counseling and research. She is a Registered Dietician with the Indian Dietetic Association and Certified Diabetes Educator recognized by the International Diabetes federation . She is also interested in ancillary sciences such as Yoga and Naturopathy.