Following a nutritious diet, getting regular exercise, and getting enough sleep help regulate your metabolism. Some foods, like hot peppers, and supplements, like caffeine, may also help improve it.

Metabolism is a series of reactions that occur in the body to provide it with energy from the food you eat. People also use it to describe the rate at which your body burns calories.

The terms “fast metabolism” and “slow metabolism” often refer to the rate at which the body converts calories into usable energy.

However, the relationship between metabolism and body weight isn’t always straightforward.

Metabolism and body weight are connected. Weight loss generally leads to increased metabolism, but significant weight loss can decrease it.

Keep reading to learn ways to improve your metabolism and some things that likely won’t help.

Metabolism is the group of chemical processes that convert carbohydrates, proteins, and fats from food into the energy cells need to function.

Your metabolic rate is how long it takes your body to process and burn energy, or calories, from the food you eat. Your basal metabolic rate (BMR) is the amount of energy, or calories, your body needs to maintain basic functions when you’re resting. It’s how many calories you would need to survive if you never moved.

In people and other mammals, BMR increases when muscle mass is more than 40% of total body weight. This is because muscle generally uses more energy than fat.

However, if muscle mass is less than 30% of your body mass, BMR will likely be reduced. This can also reduce the ability to regulate body temperature and cause reduced activity levels.

How much you move, both in general and with exercise, also reflects the total number of calories you burn. You also burn calories digesting food, a process called diet-induced thermogenesis.

What influences BMR?

Several things influence your BMR:

  • Genetics: The calories you burn per day are largely determined by genetics.
  • Age: Your average BMR decreases by 2% per decade after age 20.
  • Sex: Males tend to have a higher BMR than females.
  • Body makeup: Your BMR will be higher if you have more muscle and less fat.
  • Weight: As your weight increases, so does your BMR, as it takes more energy to support it.
  • Height: Tall people tend to have a higher BMR than shorter people.

Certain medical conditions, medications, and climates can also affect your BMR.

Some companies sell products that supposedly boost metabolism. Most claim they do this through a process called thermogenesis, or increased heat production. This process stimulates energy use, increases metabolism, and helps burn calories.

However, these products are unlikely to lead to meaningful improvements to your metabolism.

Some components in food and drinks may slightly increase the number of calories you burn in a day.

Capsaicin

Capsaicin is the chemical that puts the hot in jalapeños. There’s some indication it may help promote weight loss. An older 2012 review of 20 research studies found that capsaicin may increase the calories you burn by approximately 50 calories daily. Those calories can add up over time, contributing to long-term weight loss.

To increase capsaicin in your diet, you can eat more peppers. Capsaicin is also available as a supplement.

Green tea

Numerous studies have been conducted on the effectiveness of green tea for weight loss, but few have reported significant results.

One older 2012 study suggests that catechins and caffeine found in green tea may help support weight maintenance and increase metabolism. However, a 2013 study in people with diabetes did not find a difference in metabolism between groups who drank either 2 or 4 cups of green tea and those who drank none for two months.

Green tea is considered a safe addition to most people’s diets. Still, it’s best to talk with a doctor before drastically increasing your consumption, especially if you are pregnant or have other health conditions.

You can also take green tea extract as a supplement.

Resveratrol

Resveratrol is a substance found in the skin of:

  • red grapes
  • mulberries
  • Japanese knotweed
  • peanuts

A 2022 review of randomized clinical trials in humans notes that more research is still needed, as research on resveratrol’s effects on weight loss and metabolism has been inconclusive. The researchers note that there are many variables, so they can’t draw conclusions specific to this benefit.

You can also get resveratrol as a supplement.

Caffeine

Caffeine can increase thermogenesis and increase your basal metabolic rate. This may also help support weight loss.

Most caffeine supplements contain about 200 mg of caffeine, while one cup of coffee contains about 95 mg. However, if you drink caffeine regularly, its metabolic effects might be lessened.

Talk with your doctor before adding more caffeine to your diet, especially if you are pregnant or have other medical conditions.

You can get caffeine through coffee or tea, such as black tea, green tea, and matcha, though if you add sweeteners and milk, you will consume more calories, which may negate any potential weight loss benefits. You can also take caffeine as a supplement.

Some supplements may have limited effects on your basal metabolic rate.

L-carnitine

L-carnitine is a substance that helps your body turn fat into energy. While your body produces it in your liver and kidneys, you can also find it in:

  • meat
  • dairy products
  • nuts
  • legumes

L-carnitine may help manage certain health conditions, including:

  • heart disease
  • peripheral artery disease
  • diabetic neuropathy

But its use as a dietary supplement for weight loss is questionable.

A 2020 review of research suggests that taking L-carnitine supplements significantly reduced body weight, body mass index (BMI), and fat mass. However, it did not affect belly fat or body fat percentage.

According to the Office of Dietary Supplements, there is no identified tolerable upper limit for L-carnitine, but taking 3 grams daily caused side effects, including:

  • nausea and vomiting
  • abdominal cramps
  • diarrhea
  • fishy body odor
  • seizures in people with a seizure disorder
  • muscle weakness in people with kidney issues

People may promote the use of other foods and supplements without adequate evidence behind them. In some cases, the evidence hasn’t supported the theory that it would work, and other times, the evidence is mixed.

Though promoted as metabolism boosters, these items are less likely to work:

  • Chromium picolinate: Though chromium might have a beneficial effect on insulin, researchers haven’t proven this. It used to be understood as a trace chemical, but it does not appear necessary for any bodily processes. Because of this, there is no established tolerable upper limit.
  • Conjugated linoleic acid (CLA): CLA may support weight loss, but most of the research that suggests this has been done in animals. The results from studies in humans have been weaker.

It’s possible to improve your metabolism. But even with taking metabolism boosters, it isn’t likely to be a quick change. The most significant changes to metabolism come from gaining muscle mass and reducing fat mass.

You can do this through a combination of habits that support your overall health, including:

  • getting regular exercise, including muscle-building activities like weight training
  • eating a nutritious diet that contains lean protein and nutrients from fruit, vegetables, and legumes
  • reducing your total calorie intake and increasing your energy expenditure (how many calories you burn)
  • getting enough sleep, which can help support your overall health

Despite the hype, supplements promoted as fat busters and metabolism boosters rarely significantly affect weight loss. If you want to lose weight, cutting calories from your diet and exercising more regularly are probably your best bets. You can also try adopting an eating plan that you can stick with long-term.

Ask your doctor for more advice on losing weight in safe and sustainable ways. And talk with them before trying any weight loss medications or supplements. Having your doctor help you assess the potential benefits and risks is best.