Your metabolism is the chemical engine that keeps you alive.
The speed at which it runs varies by individual. Those with slow metabolism tend to have more leftover calories, which get stored as fat.
On the other hand, those with fast metabolism burn more calories and are less likely to accumulate a lot of fat.
This article reviews why some people have fast metabolism and how you can speed up your metabolism to burn more calories.
Metabolism refers to all the chemical processes in your body. The faster your metabolism, the more calories your body needs.
Metabolism is the reason some people can eat a lot without gaining weight, while others seem to need less to accumulate fat.
The speed of your metabolism is commonly known as metabolic rate. It’s the number of calories you burn in a given amount of time, also known as calorie expenditure.
Metabolic rate can be divided into several categories:
- Basal metabolic rate (BMR): Your metabolic rate during sleep or deep rest. It is the minimum metabolic rate needed to keep your lungs breathing, heart pumping, brain ticking, and body warm.
- Resting metabolic rate (RMR): The minimum metabolic rate required to keep you alive and functioning while at rest. On average, it accounts for up to 50–75% of total calorie expenditure (1).
- Thermic effect of food (TEF): The number of calories burned while your body is digesting and processing food. TEF usually represents about 10% of your total energy expenditure (2).
- Thermic effect of exercise (TEE): The increase in calories burned during exercise.
- Non-exercise activity thermogenesis (NEAT): The number of calories required for activities other than exercise. This includes fidgeting, changing posture, standing, and walking around (3).
SUMMARY Metabolic rate is also known as calorie expenditure. It is the number of calories your body uses in a given amount of time.
Numerous factors affect your metabolic rate, including:
- Age: The older you get, the slower your metabolic rate. This is one of the reasons that people tend to gain weight as they age (4).
- Muscle mass: The greater your muscle mass, the more calories you burn (5).
- Body size: The bigger you are, the more calories you burn (6).
- Environmental temperature: When your body is exposed to cold, it needs to burn more calories to prevent your body temperature from falling (7).
- Physical activity: All body movements require calories. The more active you are, the more calories you’ll burn. Your metabolism will speed up accordingly (8).
- Hormone disorders: Cushing’s syndrome and hypothyroidism slow down metabolic rate and increase your risk of weight gain (9).
SUMMARY Multiple factors affect metabolic rate, or the number of calories burned. These include age, muscle mass, body size, and physical activity.
Metabolic rates vary between people from birth.
In other words, some people are born with a faster metabolism than others.
One thing is clear — not everyone is created equal when it comes to metabolic rate.
Most of this variation is due to people’s age, as well as their environment and behavior. However, the role of genetics in these individual differences needs to be studied further.
SUMMARY Metabolic rates vary by individual, even among infants. However, it is unclear how much of this variation is due to genetics.
Metabolic adaptation, also known as adaptive thermogenesis or “starvation mode,” may also play an important role in the development of obesity.
Starvation mode is your body’s response to a calorie deficit. When your body doesn’t get enough food, it tries to compensate by reducing its metabolic rate and the number of calories it burns.
SUMMARY Metabolic adaptation or starvation mode is when metabolic rate slows down during a calorie-reduced diet or a fast. It varies between people and tends to be more pronounced among obese individuals.
Here are eight simple methods.
1. Move Your Body
All body movement requires calories. The more active you are, the higher your metabolic rate.
Even very basic activity, such as standing up regularly, walking around, or doing household tasks, makes a major difference in the long run.
This boost in metabolic rate is technically known as non-exercise activity thermogenesis (NEAT).
There are several ways in which you can boost NEAT. If you spend a lot of time sitting, here are a few strategies:
- Stand up regularly and walk around
- Take the stairs whenever possible
- Do household tasks
- Fidget by bouncing your legs or tapping your fingers
- Chew calorie-free gum (30)
- Use a standing desk (31)
Another 10-person study showed that spending one afternoon standing burned an extra 174 calories compared to sitting (33).
Even seemingly insignificant activities like typing may increase your metabolic rate by 8% compared to doing nothing (32).
In the same way, fidgeting can make a significant difference (34).
One study found that people who sat motionless for 20 minutes temporarily increased their calorie expenditure by 4%, compared to when they lay motionless.
In contrast, fidgeting while seated increased calorie expenditure by a whopping 54% (35).
Regular exercise is highly recommended for anyone who wants to lose weight or improve their health. But even light activities like walking around, doing household tasks, or fidgeting can give you an advantage in the long run.
2. Do High-Intensity Workouts
One of the most effective forms of exercise is high-intensity workouts, also known as high-intensity interval training (HIIT).
HIIT is when exercise involves quick and very intense bouts of activity, such as sprints or fast push-ups.
3. Strength Train
In addition to the direct effect of the exercise itself, strength exercises promote the growth of muscle mass.
One study showed that doing strength exercises for 11 minutes a day, three times per week, resulted in an average increase of 7.4% in resting metabolic rate after half a year — and an additional 125 calories burned per day (40).
In fact, a study in overweight women showed that doing daily strength exercises on an 800-calorie diet prevented decreases in muscle mass and metabolic rate, versus those who didn’t exercise or only did aerobics (46).
4. Eat Protein
Eating adequate amounts of protein is essential if you want to build or maintain your muscle mass. But dietary protein also has other important qualities.
In fact, protein may increase metabolic rate by 20–30%, whereas carbs and fat cause a 3–10% increase or less (48).
5. Don’t Starve Yourself
While eating less is a key weight loss method, eating too little is usually counterproductive in the long term.
That’s because calorie restriction causes a decrease in your metabolic rate.
This effect is known as starvation mode or metabolic adaptation. It is your body’s way of warding off potential starvation and death.
Studies in obese people suggest that the starvation response may significantly reduce the number of calories burned. For instance, one study indicates that this slowdown in metabolic rate spares up to 504 calories per day (60, 61).
6. Drink Water
Temporarily boosting your metabolic rate doesn’t have to be complicated. It’s as simple as going for a walk or drinking a glass of cold water.
Drinking cold water has an even greater effect than warm water, as this requires your body to warm it up to body temperature.
It seems that increasing your water consumption is also beneficial for your waistline. Several studies show that drinking 34–50 ounces (1–1.5 liters) of water daily may lead to significant weight loss over time (64, 69).
You can maximize these benefits by drinking water before meals, as it also fills you up and reduces calorie intake (70).
7. Drink Caffeinated Beverages
For weight loss purposes, sugar-free beverages like plain, black coffee are best. Like water, cold coffee may be even more advantageous.
8. Get Good Sleep
One study showed that metabolic rate decreased by 2.6% when healthy adults slept for only four hours per night for five days in a row (77).
Another five-week study determined that sustained sleep disruption, along with irregular sleeping times, reduced resting metabolic rate by 8%, on average (78).
SUMMARY There are numerous things you can do to boost your metabolism. These include drinking cold water, sipping on coffee, getting more sleep, exercising, and eating protein.
Although your basal metabolic rate is largely beyond your control, there are various ways to increase the number of calories you burn.
The strategies mentioned in this article can help you boost your metabolism.
However, metabolism isn’t everything when it comes to weight loss. It’s also vital to eat a healthy, well-balanced diet.