HOW TO LOSE WEIGHT AND TO KEEP IT OFF? PART 1
BODY’S BASIC METABOLISM
WHAT IS METABOLISM? KNOWING METABOLISM MAY LEAD US TO KNOW OUR BODY BETTER.
Metabolism could be defined as biochemical processes that occur within every living cell to provide energy and vital biological functions from the consumed foods nutrients, to maintain life.
For better understanding of our body’s basic functional metabolism, I believe we should supplement the definition of metabolism, with further questions and answers:
Q 1- How many food calories do we need in a day, to stay alive, heathy and functioning?
A 1- Scientific studies have shown that adult male need between 2,000- to- 3,000 food calories, and adult females need 1,600- to-2,400 food calories per day.
Q 2- What percentage of food calories we consume daily goes to fuel chemical reactions that take place in the cells to keep us alive and functioning?
A 2 – It is estimated that 55-to-75 percent of daily food calories goes to fueling of, still not very well understood, vital chemical reactions in our cells.
Q 3 – What happens if we consume more calories from our foods and drinks more than our body’s need?
A 3 - Excess calories that are not utilized during our daily metabolic and physical activities are converted into fat and deposited in fat cells and tissues as extra weight.
Q 4 – How busy our cells, throughout the day, with vital biological functions?
A 4 - Our body’s cells are metabolically much more active in the morning and the daytime, when we are awake and most active. At night, when we rest and especially during our sleep, metabolic activities and energy expenditure of our cells drop significantly. Therefore, nighttime or late at night eating, the food calories can’t be used as fuel, and results in more weight gain. Eating only when our cells are most active, is called “Chrono-nutrition” which is very important if you want to prevent weight gain.
Q 5 – Does our metabolism stay the same level during our entire life span?
A 5 - A recent and very interesting multi-author scientific article published in Science Journal tries to address this question. Researchers, using data obtained from 6400 subjects, age range changing from 8 days to 95 years, found that our metabolism goes through four (4) distinct stages during our life span:
Newborn’s metabolism starts rapidly increasing until 15 months, it is like burning 4,000 calories a day. After age 1 or 2, energy expenditure starts to decline gradually until the age 20.
After age 20, the energy expenditure holds steady until about age 40. Surprisingly, the energy expenditure remains the same during pregnancy and menopause.
At around age 60, energy expenditure starts to decline and continues to decline until the end of life. Therefore, the older we are the lesser energy calories we need.
Q 6 – Do men have faster energy metabolism than women?
A 6 - No, but men have bigger body size and more muscle mass than women. Muscles require and burn more energy. That is why men can lose weight more easily than women.
Q 7 – What is the most precise method to calculate total energy expenditure?
A 7 - Only after 1980s, a precise new method called “double labelled water” is used to calculate total energy expenditure. People given isotope labelled water, in which the hydrogen and oxygen molecules were labelled with isotopes. After drinking this water, subjects resume their daily activities, but provide sample of urine and blood within a week. Labelled hydrogen passes intact through the body. But some of the labelled oxygen is exhaled as CO2 with respiration, as a waste product from our cells while transforming fuel calories to energy. This makes researchers to calculate how much CO2 is exhaled and calculate total energy expenditure.
Scientific studies have shown that there are wide differences, in energy expenditures among peoples, even with the same size, sex and lifestyles. This is most likely due to genetic makeup of individuals and, different living environmental factors.
Even though working with isotope labelled water is very expensive and reserved for few research centers, this new study has raised many new questions on its own:
- What are the switches that turn our body’s metabolic activities up and down during certain times in our wide life span? Can these switches be modified by certain medications, so that aging could be delayed?
- Shouldn’t we adjust our nutritional requirements and the dosage of medications, to match the rate metabolic activity?
- Why metabolic rate and energy expenditure increase during the course of a chronic illness and, what could be done about it?
- Can energy expenditure be increased, by medications to prevent obesity?
So, it appears that the nuance of life is not so easy to understand, more studies and time are needed to understand it better.
