Metabolism is the chemical engine that provides energy for life processes. Its speed differs from person to person.

People with slow metabolism have a tendency to burn fewer calories, which get stored as fat in the body. This explains why some people struggle to lose and maintain weight.

Those with fast metabolism, on the other hand, tend to burn more calories and are unlikely to store a lot of fat.

Here we define metabolism and discuss why some people have fast metabolism. We also detail herein some ways to rev up your metabolism to burn more calories.

What is metabolism?

Referring to all the chemical processes in the body, metabolism allows some people to eat a lot without having to worry about gaining weight; other people might also need less of it to accumulate fat.

Metabolic rate, which is the speed of your metabolism, refers to the amount of calories you burn at a specific length of time—also called calorie expenditure. It can be divided into different categories:

Resting metabolic rate (RMR): This refers to the total amount of calories burned while at rest. RMR constitutes approximately 50–75% of the total calorie expenditure and supports basic neurological functions, organ function, blood circulation, and breathing.

Basal metabolic rate (BMR): BMR refers to your metabolic rate during deep rest or sleep.  This is necessary to keep your brain ticking, lungs breathing, heart pumping, and body warm.

Thermic effect of food (TEF): This refers to the number of calories burned after ingestion of a meal.

Thermic effect of exercise (TEE): This refers to the amount of calories burned during all physical activity, including standing up from a seated position and high-intensity interval training.

Non-exercise activity thermogenesis (NEAT): NEAT refers to the energy expended for activities other than exercise, such as changing posture, fidgeting, walking around, and standing.

Factors affecting your metabolic rate

There are several factors that affect your metabolic rate, and these include the following:

Muscle mass: More calories are burned when there is more muscle in your body and less fat.

Body size: More calories are burned when you are bigger.

Age: Your metabolic rate slows down as you age; thus, people tend to experience weight gain as they age.

Physical activity: Every move your body makes requires calories. Thus, more calories are burned when you are more active, making your metabolism speed up accordingly.

Hormone disorders: Hormone disorders, such as hypothyroidism and Cushing’s syndrome, slow down your metabolic rate, thereby increasing your risk of weight gain.

Environmental temperature: Your body needs to burn more calories when it is exposed to cold to prevent your body temperature from dropping.

Why do some people have fast metabolism and others have slow?

Every individual has different metabolic rates since birth. Some people are born with fast metabolism, while others with slow metabolism.

Genetics may be one of the several contributing factors; however, scientists disagree on the extent to which they affect obesity, weight gain, and metabolic rate.

Interestingly, obese people have been shown in studies to have a higher total and resting metabolic rate than those with normal weight. This is partly due to the fact that obese people have greater number of muscle to support excess weight.

Yet, obese people have been indicated in studies to have higher metabolic rates regardless of their muscle mass.

On the contrary, formerly obese people have been shown in other studies to have an average of 3–8% lower metabolic rate compared to those who have never been obese.

Generally, metabolic rate differs from person to person, depending on their age, behavior, and environment. However, further study on the role of genetics on these individual differences is necessary.

What is starvation mode?

Metabolic adaptation, also called “starvation mode,” plays a key role in the development of obesity. It is the natural response of your body to a long-term calorie deficit.

When you lower your intake of food, your body tries to reduce its metabolic rate and the amount of calories it burns in order to compensate for the food it didn’t get.

The change in the metabolic rate during calorie restriction and weight loss is different from person to person.

When the metabolic rate decreases, it makes it more difficult to lose weight by fasting or dieting. This metabolic slowdown is more common in obese individuals.

How to increase metabolism?

Losing weight doesn’t always mean reducing your calorie intake. It should also include strategies to rev up metabolism. Here are eight easy ways to do so:

1. Engage in High-Intensity Workouts

High-intensity interval training (HIIT) is one of the most effective forms of exercise that involves quick and intense sessions of activity, including fast push-ups or sprints.

HIIT can significantly increase metabolism, even after the workout—this effect is called “the afterburn.”

2. Do Strength Training

Strength training is another excellent way to rev up metabolism.

The exercise itself has a direct effect and promotes muscle mass growth.

It can be noted that muscle mass, unlike fat mass, increases the amount of calories burned while at rest. Thus, more calories are burned when you have more muscle.

In fact, doing strength exercises for 11 minutes every day, thrice a week, has been shown in one study to result in an additional 125 calories burned per day and an average increase of 7.4% in resting metabolic rate after six months.

With aging also comes muscle loss and drops in metabolic rate; however, you can partially counteract this adverse effect by doing regular strength exercise.

In the same manner, a weight loss diet that involves calorie restriction can cause muscle mass loss and drops in metabolic rate. You can also help prevent the decline by doing strength training.

In fact, doing daily strength exercises on an 800-calorie diet has been shown in a study in overweight women to help prevent reductions in muscle mass and metabolic rate.

3. Make Movement

Your body needs calories to move; thus, the more movements you make, the higher your metabolic rate will be. The increase in metabolic rate is called the non-exercise activity thermogenesis (NEAT).

Even basic activities, such as walking around, standing up regularly, or doing household chores, can have a huge impact in the long run.

There are a number of ways to increase NEAT. If you sit a lot throughout the day, you can do any of the following:

• Bounce your legs or tap your fingers
• Stand up regularly
• Walk around
• Take the stairs
• Use a standing desk
• Do household chores
• Chew calorie-free gum

If your job involves sitting throughout the day, you can still increase the number of calories you burn by 16% by using a standing desk.

In fact, spending one afternoon standing has been shown  in another 10-person study to burn an extra 174 calories than sitting.

Even typing or any other seemingly insignificant activities may boost your metabolic rate by 8%, as compared to doing nothing.

In addition, fidgeting can also cause a significant change.

In fact, people who sit motionless for 20 minutes have been found in one study to temporarily up their calorie expenditure by 4%. Fidgeting while sitting has been shown to increase calorie expenditure by 54%.

Regular exercise can be beneficial for weight loss and overall health improvement, but even seemingly insignificant activities, such as fidgeting, doing household tasks, or walking around, can be advantageous in the long run.

4. Get Adequate Quality Sleep

Not only is sleep deprivation harmful to your general health. It may also cause a drop in metabolic rate, thereby increasing your risk of weight gain.

In fact, metabolic rate has been shown in one study to decrease by 2.6% when healthy adults slept for only four hours every night for five consecutive days.

Additionally, sustained sleep disruption, combined with irregular sleeping times, has been determined in another five-week study to reduce resting metabolic rate by 8%.

Sleep deprivation has been linked to increased risk of weight gain and obesity.

5. Don’t Starve Yourself

Although eating less is key to achieving weight loss, consuming too little food can be counterproductive in the long run, as calorie restriction can cause a drop in your metabolic rate.

This effect is called metabolic adaptation or starvation mode. It’s your body’s natural response to long-term calorie restriction to ward off potential starvation and death.

Consistently eating < 1000 calories daily has been shown in research to cause a significant drop in metabolic rate that remains even after you stop the diet.

Starvation response has been suggested in studies in obese people to significantly reduce the number of calories burned. For example, this decrease in metabolic rate has been indicated in one study to spare up to 504 calories per day.

Intermittent fasting can remarkably help minimize this effect.

6. Load Up on Protein

Loading up on protein is beneficial for building and maintaining muscle mass. In addition to that, dietary protein also has other benefits to offer.

For example, although all food increases metabolic rate, which is called the “thermic effect of food,” protein-rich foods give a much stronger effect compared to carb- and fat-rich foods.

Protein has been shown to boost metabolic rate by 20–30%, while carbs and fat can result in a 3–10% increase or less.

This may help prevent weight regain or promote weight loss after a weight loss diet.

TEF is particularly high during the first few hours after you wake up, or in the morning. If you want to maximize the effect, eating a large proportion of your daily calories early in the day or a few hours after you wake up is a great idea.

Loading up on protein can help counteract the drop in metabolic rate and loss of muscle mass associated with weight loss.

7. Drink Plenty of Water

Temporarily increasing your metabolic rate doesn’t have to be an uphill battle. Drinking a glass of cold water or going out for a walk can simply make a difference in the long run.

Drinking water has been shown in many studies to cause an increase in the number of calories burned; this effect is called water-induced thermogenesis.

Drinking cold water produces a better weight loss effect compared to drinking warm water. This is because your body needs to warm it up to body temperature, leading to increased calorie burning rate.

Study results are however mixed.

About 500-ml cold water may lead to 5–30% increase in the number of calories burned for 1–1.5 hours afterward.

Consuming more water is also beneficial for your waistline. In fact, drinking 1–1.5 liters of water daily has been shown in several studies to cause significant weight loss over time.

Drinking water before meals can help maximize these benefits, as water fills you up, thereby reducing calorie intake.

8. Drink Caffeinated Drinks

Although plain water is the best go-to drink, caffeinated, low-calorie drinks, such as green tea and coffee, are beneficial as well.

In fact, drinking caffeinated beverages has been shown in controlled studies to temporarily speed up your metabolic rate by 3–11%.

Sugar-free drinks, like plain, black coffee, are best; they are also advantageous.

Conclusion

Metabolism is the complex chemical process that provides energy for life processes, e.g., food breakdown.

Your basal metabolic rate is something that you can’t control; however, there are some things you can do to increase the number of calories you burn.

The abovementioned strategies can help improve your metabolism.

However, it is important to note that weight loss isn’t all about metabolism. Eating a healthy, well-rounded diet is also necessary.