What causes the metabolism to slow down?

“People might have a fast, slow, or average metabolism, regardless of their body size and composition,” says Dr. Chih-Hao Lee, professor of genetics and complex diseases at Harvard’s T.H. Chan School of Public Health. health.harvard.edu. Though age plays a major role in that.

You don’t have much influence over the resting metabolism. Sadly, the control tends to be minimal and negative.

What’s the difference between a Fast & Slow Metabolism?

A fast metabolism means that your body has an efficient system for breaking down food and using its nutrients efficiently. Slow metabolism may mean that your body doesn’t break down food well, leading to weight gain.

The best thing you can do to boost your metabolism is to exercise regularly. Exercise increases levels of hormones like growth hormone and testosterone, both of which help increase metabolic rate. It also helps build muscle mass, making your body stronger and better able to use fat as fuel.

Physical Activity and Metabolism Slow Down

While you can’t regulate your basal metabolism, you can influence how many calories you burn by increasing your physical activity. More activity burns more calories and vice versa. In reality, some individuals with a quick metabolism are just more active and fidgety than others.

These are the main factors that slow metabolism.

Inherited Genes

Body metabolism converts food into energy. So if your body burns calories slowly when you sleep, you probably inherited it from your parents.

Slimming Down

Slimming down usually includes muscle loss, so the body is smaller and doesn’t have to work as hard every minute to stay running. But the slow down in metabolism following weight reduction is frequently much more than expected, given the person’s new body size.

Low-Calorie Intake

While it’s difficult to increase the metabolic rate, researchers have discovered ways to cut it down, such as severe weight reduction programs.

Insufficient calorie intake slows metabolism. Although a calorie deficit is required for weight reduction, too low a calorie intake may be harmful. Your body detects food scarcity and slows your metabolism when you drastically reduce your calorie intake.

Studies on lean and overweight individuals show that eating less than 1,000 calories per day may significantly slow your metabolism.

Obese women who ate very few calories per day for 4–6 months had substantially lower resting metabolic rates. Moreover, even after increasing their caloric intake for five weeks, their resting metabolic rates remained lower than before.

Even modest calorie restriction may decrease metabolism. If you want to lose weight, don’t limit your calorie intake too much or too long.


Hormones control our metabolism. Some hormonal diseases impact the thyroid. Hypothyroidism occurs when the thyroid does not produce or release enough thyroid hormone. It slows your metabolism throughout your body.

Hyperthyroidism (overactive thyroid) – the gland produces more hormones than needed, speeding up metabolism. Hypothyroidism (underactive thyroid) causes unexpected weight gain, fatigue, sadness, and constipation. Graves’ illness is the most frequent cause. Hyperthyroidism causes increased hunger, weight loss, anxiety, and diarrhea.

A diet lacking in iodine, for example, lowers thyroid function and slows metabolism.

Lack of Protein

Protein is vital for attaining and maintaining a healthy weight. A high protein diet may help you feel full while also increasing your body’s calorie-burning rate. The thermic impact of food is the increase in metabolism after digestion (TEF).

Protein has a greater thermic impact than carbohydrates or fat. Studies show that consuming protein temporarily boosts metabolism by 20-30%, compared to carbohydrates at 5-10% and fat at 3-4%.

So, lack of protein will result in high carbs or fat diets, due to which the thermic effect will be less and metabolism will slow down.


Sedentism may reduce the number of calories you burn each day. Many individuals live sedentary lives, which may harm their metabolism and general health. Even simple physical activities like standing up, cleaning, and climbing stairs may help you burn more calories.

Non-exercise thermogenesis is this kind of activity (NEAT). A high level of NEAT may burn up to 2,000 more calories each day. But most individuals can’t afford such a big rise. Inactivity decreases daily calorie burn, so minimize sitting and enhance overall exercise.

Lack of Quality Sleep

Sleep is vital for a healthy body. Sleeping less may raise your chances of heart disease, diabetes, and depression. Insufficient sleep has been linked to slower metabolism and an increased risk of weight gain.

In one study, healthy individuals who slept 4 hours each night for five nights had a 2.6% reduction in resting metabolic rate. However, after 12 hours of sleep, their rates returned to normal.

Sleeping during the day instead of at night exacerbates insomnia. This sleep pattern throws off your body’s circadian cycles.

A five-week study found that sleep restriction and circadian rhythm disturbance reduced resting metabolic rate by 8%. Sleeping at night rather than during the day may help maintain your metabolic rate.

Sugary Drinks

Sugar-sweetened beverages are unhealthy. High consumption has been related to insulin resistance, diabetes, and obesity. Sugar-sweetened drinks have several harmful consequences due to fructose. For example, table sugar has 50% fructose, whereas high fructose corn syrup has 55%. Sugar-sweetened drinks may slow metabolism.

In a 12-week trial, overweight and obese individuals who drank 25% of their calories as fructose-sweetened drinks had a substantial decrease in metabolic rate.

Loss of Muscular Tissue

No Strength Training In general, individuals with more muscle than fat have a quicker metabolism.

We acquire fat and lose muscle as we age. It partly explains why metabolism slows with age.

Gradual loss of muscular tissue, hormonal and neurological changes decrease metabolism with age.

Weight training is a fantastic way to keep your metabolism going. Strength training has been proven to improve the metabolic rate in individuals with heart disease, diabetes, and obesity.

Strength training seems to increase energy consumption. It increases muscular mass, which is a major component of fat-free mass. In addition, increasing your fat-free mass improves your resting calorie burn. But you have to fight the natural tendency to eat more to compensate for the increase in metabolism.

But not performing any strength exercise may slow down your metabolism, particularly during weight reduction and aging.

Some Medicines Slow Down Metabolism.

Among them are numerous antidepressants and antipsychotics used to treat schizophrenia. Many other drugs, such as cardiac medicines, may do the same thing.

Water – An Interesting Phenomenon

Not that it means anything. According to modern science, if you drink cold water, the metabolism rate increases as the body engages in bringing water to body temperature, thus expending eight calories in the process. Eight calories can not make any difference.

According to Ayurveda, drinking cold water slows down metabolism as the whole body engages in bringing it up to body temperature instead of engaging in digesting food. So food stays undigested in the body. It also results in various other problems, like bloating, gases, etc.

While we must try and keep fit, our goal to stay fit can lead to fast and slow down in metabolism if we are not cautious about it. We shouldn’t go overboard in doing the same. Balance and change in lifestyle can only give us long-term weight loss results.

New Theory about the slowdown in Metabolism

Metabolism in adulthood does not slow as commonly believed, study finds.

According to a recent study published by researchers from University College London, the metabolic rate of adults is the same at any given time during their lives. The findings contradict previous studies that have suggested that people’s metabolisms decline with age and are replaced by fat cells.

“We found no evidence for this,” said Dr. David Jenkinson, lead author of the paper. “Our results suggest that there is little change in energy expenditure over the course of an individual’s lifetime.”

But more research is needed on this.