Most people are sure that the slowdown in metabolic processes begins already from the age of 20 – as a result of which the body more actively stores excess weight on the stomach and sides. Additionally, it is often believed that men have faster metabolisms than women (especially after menopause).
However, a scientific study published last week refutes both of these claims. Scientists, based on a study of the metabolism of 6,500 people, discovered that metabolism undergoes four changes throughout life, and gender has a much lesser impact on it than commonly believed.
Metabolism – what is it?
To put it as simply as possible, metabolism is the ability of the body to process the calories contained in food into energy for life. At the same time, about 65% of the total energy the body spends on the work of only 4 organs – the brain, heart, liver and kidneys.
Despite the scientific community’s awareness of the concept of “calorie” for over 100 years, most studies investigating the mechanisms of calorie utilization encounter difficulties in altering the body’s actual energy consumption. To achieve this, measuring the level of carbon dioxide exhaled by an individual over a 24-hour period is required.
The study cited above, published in the journal Science, summarizes the work of more than 80 authors over 40 years in laboratories around the world. Researchers conducted a comprehensive analysis of metabolic parameters in a total of 6,500 individuals ranging from 8 months to 95 years of age.
A word from the authors
In an explanatory note, the authors of the study note that many of the findings directly contradict the traditional understanding of metabolism – starting a new era in the study of metabolic mechanisms.
While the main postulate of weight loss remains unchanged, many details are viewed from a different perspective.
For example, scientists unequivocally confirmed that total body weight and activity level have a greater influence on the number of calories burned, while age or gender does not.
4 phases of metabolism in human life
The published study’s key findings reveal that people’s metabolism divides into four distinct phases based on age.
- Infancy (under 1 year of age). The maximum number of calories burned per unit of body weight is about twice that of an adult.
- Age from 1 year to 20 years. During this period, the metabolic rate gradually slows down – by about 3% every year.
- Age from 20 to 60 years. Stable and unchanged metabolic parameters.
- Age over 60 years. The metabolic rate slows down by about 0.7% every year. As a result, at the age of 90, the metabolism is 20% lower than at the age of 60.
Difference between men and women
The study’s second conclusion is that when considering the same body weight, including comparable indicators of total muscle mass and percentage of body fat, the energy consumption of men and women can be deemed equal.
That is, the opinion that men need more calories for life than women is true only when a man leads a more physically active lifestyle.
Important disclaimers
Scientists note that an individual’s energy needs can differ from the average for people with his weight and a comparable level of activity by 25 percent up or down.
Because of this fact, there are even more reasons not to trust the traditional calorie calculation formula. We, as always, advise you to consult on this issue with a specialist.
The age-related slowdown in metabolism
Apparently, the reason for the slowdown in metabolism after 60 years is the deterioration in the functioning of internal organs. The same fact is probably the cause of the development of chronic diseases.
However, although scientists were preparing to find a slowdown in metabolism in women after menopause, the numbers did not show any correlation.
Practical Conclusions
- Metabolism begins to slow down as early as adolescence.
- Regular physical training and maintenance of muscle mass keep the metabolism active until the age of 60.
- The reason for gaining excess weight lies in excess calorie intake and an inactive lifestyle.
- The actual calorie intake of the body may differ by ±25% from the calculated figures.
New scientific research indicates that teenagers experience a 3% annual slowdown in metabolism until the age of 20, while metabolism remains unchanged from 20 to 60 years old. In addition, the floor has a much smaller impact on energy costs than previously thought.