What is metabolism and how to improve it?

By: Nutrition expert- Vidula Kozarekar, Mumbai.

Email id- vidula708@gmail.com

Metabolism refers to the whole sum of reactions that occur throughout the body within each cell and that provide the body with energy. We are dependent on metabolism to carry out certain bodily functions like breathing, digestion, thinking, circulation of blood, adjusting body temperature in hot and cold weather and so much more.

In humans, about 90% of energy ingested is metabolizable energy, with the rest being lost in the feces, urine, or leaving the body via the skin (1). Total daily energy expenditure (TDEE) is comprised of three components:

  • resting (or basal) metabolic rate (RMR),
  • the thermic effect of food (TEF; also known as diet-induced thermogenesis), and
  • Activity energy expenditure.

RMR refers to the energy required to sustain the biochemical systems of the body at complete rest and accounts for ∼70% of TDEE in sedentary individuals (2). RMR can be further divided into:

  • Energy expenditure during sleep (sleep metabolic rate; SMR) and
  • Energy to maintain wakefulness without physical activity, with the latter contributing ∼5% of RMR with slight variations across race, sex, and obesity (3).

Components of total daily energy expenditure: (4)

Although Diet induced thermogenesis (DIT) is the smallest component, it could play a role in the development and/or maintenance of obesity.

Factors influencing thermic effect of food: (5)

  • Age
  • Physical activity
  • Energy content of meals
  • Meal composition
  • Processed v/s unprocessed foods
  • Palatability
  • Meal frequency
  • Meal duration

How to increase metabolism:

A study conducted by Yoshiko Fukuchi et al suggested that; a supplementation with lemon polyphenols may prevent or improve obesity and insulin resistance by modulating lipid metabolism and preventing metabolic syndrome as a representative, lifestyle-related cluster of diseases caused by an excessively high fat diet (6).

Muhammad S. Mansour et al showed in their study that; ginger consumption enhanced thermogenesis and reduced feelings of hunger and suggest a potential role of ginger in weight management (7).

Mette Kristensen et al found that; both Flax drink and Flax bread resulted in decreased plasma total and LDL-cholesterol and increased fat excretion. Viscous flaxseed dietary fibers may be a useful tool for lowering blood cholesterol and potentially play a role in energy balance (8).

A higher thermogenic response was observed after a meal composed of whole foods than after an equivalent and iso-caloric meal comprised of highly Processed Foods. The lower Diet Induced Thermogenic effect of the PF meal indicates greater net-energy assimilation (9).

There is a general consensus in the literature that protein stimulates dietary-induced thermogenesis to a greater extent than other macronutrients (10), (11), (12).

Sitting for longer time is dangerous to health. Try to stand up more often to burn more calories and be more active (13).

Get a good night’s sleep. Cross-sectional studies from around the world show a consistent increased risk of obesity amongst short sleepers in children and adults (14).


  1. https://sci-hub.tw/10.1079/pns19550031
  2. https://sci-hub.tw/10.1093/ajcn/55.1.242s
  3. https://sci-hub.tw/10.3177/jnsv.50.441
  4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5081410/
  5. https://www.researchgate.net/publication/332668404_The_Thermic_Effect_of_Food_A_Review
  6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2581754/
  7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3408800/
  8. https://nutritionandmetabolism.biomedcentral.com/articles/10.1186/1743-7075-9-8
  9. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2897733/
  10. https://academic.oup.com/ajcn/article/77/1/91/4689639
  11. https://rnd.edpsciences.org/articles/rnd/pdf/1996/04/RND_0926-5287_1996_36_4_ART0005.pdf
  12. https://care.diabetesjournals.org/content/25/3/425.short
  13. https://pubmed.ncbi.nlm.nih.gov/24297826/
  14. https://pubmed.ncbi.nlm.nih.gov/18517032/

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