The human body performs millions of chemical reactions every day, known collectively as metabolism. The process of converting food into energy is called metabolism. These functions are essential for sustaining life and promoting growth and tissue repair. The liver breaks down nutrients from the diet to enable regular functioning.
The rate at which the body burns calories (the metabolic rate) has a big impact on how much weight a person gains, loses, or keeps off. Metabolism is responsible for maintaining a balance between energy intake and output. The amount of energy your body burns just to keep it running while at rest is called your basal metabolic rate. There is no one answer to this question, as it varies depending on the person. However, carbohydrate metabolism generally makes up a majority of the metabolism and can account for anywhere from 50 to 80% of the energy required.
Metabolic health refers to the rate at which the body converts food into energy. A healthy metabolism can help remove toxins from the body, improve blood circulation, and make a person feel more energized. It also has positive effects on mood and energy levels, immunity, weight loss, and sleep quality. Poop problems like irritable bowel syndrome, diarrhea, or constipation are common when your metabolism is out of whack. Indirectly, poor sleep habits are also a significant problem when it comes to poor metabolic health. You should also consult a nutritionist if you experience any of these symptoms. Several tests can assess poor metabolic health.
By using continuous glucose monitoring, you can figure out how much food and activity you need to maintain your metabolic health. It is always very practical to be able to consult with a nutritionist when making food choices. If you eat the right things, your metabolism will get better, and you’ll be able to lose weight in a way that you can keep it off.
Factors Affecting Metabolism
Age
The Basal Metabolic Rate (BMR) is higher in infants and young children, peaking between ages 3 and 5. The average newborn infant’s metabolism produces approximately 25 calories per hour per square meter of the body. Metabolism, or the rate at which the body burns calories, is highest in early childhood and gradually declines throughout the lifespan.
Sarcopenia, a natural loss of muscle tissue, neurological abnormalities, and hormonal changes, slow down people’s metabolism as they age. Starting at age 30, we experience a 3-5% decline in our basal metabolic rate (BMR) every decade as we lose lean muscle mass. Resistance and strength training can help slow down or stop muscle loss, which can eventually help reduce your metabolism.
Genetics
The genes may play a role in how quickly the body metabolizes food. As a result, the BMR rates differ between families. Faulty genes can sometimes cause proteins to be processed inefficiently, leading to metabolic disorders. Most hereditary metabolic disorders are treated with a combination of a special diet and close medical supervision.
Gender
Men often have a higher metabolic rate than women. The reason women tend to have a higher body fat percentage and less muscle mass than men of comparable size is that women typically have a higher body fat percentage and less muscle mass than men of comparable size. The basal metabolic rate for women is typically 5-10% lower than men, according to a study.
Body Size
Your metabolic rate increases when you have more mass, are taller and have a larger surface area. This is because larger bodies have a higher Basal Metabolic Rate, which is the amount of energy needed to maintain basic body functions. A taller person has a different metabolism than a shorter person.
Muscle Mass
Fat tissue has a slower metabolism than muscle tissue. This means that it uses up less energy than other tissues and organs in the human body. As the amount of lean muscle mass increases, metabolism also increases. People with more muscle mass tend to have a higher metabolic rate. The more muscle mass a person has, the more calories they burn each day.
Hormonal Factors
The hormonal system manages the metabolic rate. Hormones play a role in regulating metabolism, so imbalances can impact the body’s ability to burn energy efficiently.
The thyroid gland has been linked to the most common hormonal conditions in a recent study. The thyroid gland also secretes hormones that control the rate of metabolism, including how many calories are burned.
Physical Activity
Approximately 20% of the energy our bodies use comes from our muscles when we are resting, according to a study. However, when people work out hard, their energy consumption can increase significantly. Muscles burn 717 calories per hour during vigorous physical activity.
How much energy someone burns during a workout varies depending on how intense the session is, as well as the person’s individual characteristics, such as their body type, age, state of health, and level of fitness. Working out on a regular basis gets your body used to burn calories more quickly, even when you’re not exercising. This also helps develop more muscle, which in turn makes your metabolism work more efficiently.
Body Temperature
The body’s metabolic rate increases by about 7% for every temperature increase of 0.5 degrees Celsius. Higher temperatures also increase the rate of chemical reactions in the body. A patient with a fever of 42° C (roughly 4° C above normal) would experience an increase in BMR of about 50%.
Fever increases body temperature, which causes the body’s metabolic rate to increase by 14–15%. The body’s increased metabolism undoubtedly causes this increase.
Sleep
The metabolism remains stable with enough sleep. When you don’t sleep well, it throws off your body’s natural sleep cycle. That screws around with your hormones and makes it harder for your body to use energy efficiently. A slow metabolism and a desire for unhealthy foods may be caused by not getting enough sleep.
Drugs
Certain substances can speed up your metabolism, like nicotine or caffeine. Some medications, such as antidepressants and steroids, can cause weight gain, regardless of what one eats, by slowing the metabolism.
Illness
The basal metabolic rate increases when a person is sick because the body needs to work harder to regenerate tissues and create an immune response. According to research, BMR may increase twofold due to fever, illness, or injury.
Stress
The body produces cortisol hormone in response to stress. If you’re feeling stressed, your body goes into “fight or flight” mode, releasing hormones like cortisol.
Insulin is a hormone that promotes the growth of cells and the storage of fat. It is one of the key hormones involved in fat metabolism. The body struggles to use insulin when cortisol levels are high. When insulin is not used properly, the body has a difficult time metabolizing fat and retaining fat. This then leads to a slower metabolism and weight gain.
Factors That Influence Body Weight
There are numerous factors that can influence body weight. Some factors that determine an individual are out of their control, such as developmental determinants, genetic makeup, gender, and age. There are many things that can affect a person’s weight, including things like how active they are, what they eat, and some outside factors like the environment or social pressure. The chapter looks at how different factors are linked to body weight.
Prenatal Factors
It has been documented that when females are food restricted during the first one to two trimesters of pregnancy, their progeny have a higher prevalence of obesity, diabetes, insulin resistance, and hypertension later in life. Children of survivors of the Dutch famine in World War II were more likely to be obese and have diabetes, although this was later disputed by other studies. If a pregnant woman suffers from malnutrition, it has been reported that her child is more likely to be obese and have obesity-related complications later in life. Smaller birth weights are linked to larger amounts of fat around the internal organs in adulthood, which raises the risk of heart disease. Since people from a lower socioeconomic background are more likely to be exposed to malnutrition during gestation or early childhood, the prevalence of obesity in such subgroups might be expected to be higher.
Adiposity Rebound
Weight gain is highest during the first year of life, then starts to decline around age 6. The Adiposity Rebound is when a child’s BMI and body fat start to increase again after hitting a low point around the ages of 5-7. Children who are obese at a young age appear to have a greater risk of being obese than adults. He and Karlberg found that children who experienced a rebound in weight before 8 years old were more likely to be obese as adults. However, a study by Guo and coworkers in 2000 showed that while there was no association between early age at adiposity rebound and adult BMI status in men, there was approximately twice the risk for being overweight with an early rebound in women after controlling for the effects of birth weight, adult physical activity, alcohol and cigarette use.
There are a few potential reasons why someone might have an early adiposity rebound like if they have advanced skeletal maturity, consume a lot of protein, or have parents with a high BMI. Cameron and Demerath (2002) have not found enough evidence to conclusively say that age at adiposity rebound is a critical period for developing obesity, but early adiposity rebound could be a statistical predictor of later obesity because it is closely related to early adiposity and accelerated maturation, both of which have been linked with an increased chance of developing obesity later on.
Adolescence
Although only 30 percent of adult obesity begins during childhood, 70 percent of adult obesity that begins in childhood may start during adolescence. Obesity during adolescence is linked to a variety of health problems later in life, including an increased risk of early death in men, as well as higher chances of developing coronary heart disease, diabetes, and colorectal cancer. This suggests that obesity during adolescence may have a lasting impact on an individual’s health, regardless of whether or not they are obese as an adult.
When considering developmental aspects of obesity, it is important to consider not only total fatness but also where on the body fat is distributed. The deposition of visceral adipose tissue has been found to have an independent effect on obesity-associated comorbidities, separate from the effect of total body fat. However, the developmental aspects of this deposition have not been well studied. Visceral adiposity, or fat around the organs, is associated with increased risk of cardiovascular risk factors such as elevated triglycerides and reduced high-density lipoproteins, even when total body fat is taken into account. The age at which these relationships occur is unclear. Before adolescence, there is not a lot of visceral adipose tissue deposition. However, it increases rapidly during that time.
Adulthood
There hasn’t been a lot of research on the time after adolescence, even though a majority of adult obesity starts then. There is some debate over whether or not there are additional critical periods in adulthood, but it is generally agreed that pregnancy and postpartum is a critical periods for a certain group of women. Most women appear to retain between 0.5 and 4.8 kg after giving birth, but African-American mothers may be twice as likely as Caucasian mothers to retain 9.1 kg (20 lb) or more. African-American women in the study ate more and were less physically active postpartum than Caucasian women. The study found that even when taking into account factors that could affect weight retention, such as prepregnancy weight, gestational weight gain, prenatal physical activity, parity, and socioeconomic status, African-American women still retained more weight postpartum than Caucasian women.
Several recent studies suggest that the tendency to retain weight postpartum may be affected by genetic factors. A study found that pregnant women who had high levels of leptin, a protein hormone, in their first trimester were more likely to gain weight during their pregnancy and retain weight after giving birth. There was another study where women who had just given birth to their first child and carried the ‘825T allele’ of the G-protein ß3 had higher BMIs and retained more weight postpartum than women who didn’t carry the genotype. The ‘825T allele’ is known as the ‘thrifty’ genotype.
The genotype had no effect on women who had never given birth, which suggests that it is specific to pregnancy. Only among women who engaged in low levels of physical activity was this relationship observed, supporting the idea that physical activity may mitigate the effects of genetic endowment on the potential for postpartum weight retention. Whether this particular genetic variation in this specific G protein is causally linked to the observed differences in BMI and weight retention or is merely a marker for the responsible mutation, as well as what the mechanism might be, are both questions that require further investigation.
