We all have those people in our lives that can eat whatever they want and still have abs. A lot of times we credit this to good genes or a fast metabolism. But how do you get a fast metabolism in the first place? And is it possible to alter your own metabolism to promote more fat loss?
What is Metabolism?
Although we like to think of metabolism in terms of weight management, your metabolism is a complex system that involves numerous chemical processes needed to keep you alive.
Metabolism is not just one process that you can easily manipulate, its a series of bodily functions that exist in all of your cells throughout your body. And it's primary function is not to maintain weight; it's to sustain life by converting food and reserved fuel into usable energy you need to breathe, think, pump blood, move, and keep on living.
What is Basal Metabolic Rate (BMR)
When most people speak about their metabolism, they are referring to their body's ability to burn calories, which is largely determined by your basal or resting metabolic rate (RMR or BMR).
Your BMR is the amount of energy (or calories) needed to support metabolic processes for survival while at rest. This does not include any additional calorie needs from exercise, food digestion, and daily living.
BMR is the starting place for your overall calorie needs - representing nearly 70% of your overall metabolism (1). It is essentially the main engine that fuels your calorie burn and the driving force behind the entire weight loss calorie equation.
Altering your BMR would have the largest impact on your metabolism and ability to lose weight.
Your BMR is most strongly associated with your body weight (2,3). The more you weigh, the more calories you need. This is also why many believe dieting destroys or slows your metabolism (which is not true). Cutting calories leads to weight loss, which automatically leads to lower calorie needs.
To simplify, if you gain weight your metabolism increases. If you lose weight your metabolism decreases. This is because the number of calories you need to maintain your weight changes accordingly.
How to Burn Fat
You might also commonly hear certain diet programs, workouts, foods, etc. proclaim that they can turn you into a fat burning machine! Yes, it is possible to optimize your ability to use more fat for energy, but burning fat for fuel and losing fat don't always go hand in hand.
The way your body breaks down fat for energy (also called fat oxidation) is complex and involves a number of hormones and biological processes. The body is constantly in a state of change - meaning you are always breaking down and rebuilding cells, protein, fat, etc. as part of your normal daily function. You are pretty much always burning fat, even at rest. That’s because fat is an abundant source of energy your body uses on a regular basis.
Increasing your fat burning capabilities doesn't mean you are automatically losing body fat though. Fat loss occurs when the calories you are eating are lower than the number of calories you need to run your metabolism and support your daily energy needs. Fat is burned throughout the day, and with fewer calories coming in, less fat is replaced, and overall fat loss occurs.
Similarly, storing fat from food doesn't always lead to overall fat gain. If calories are controlled, you will still burn this fat for energy throughout the day and maintain your current level of body fat.
In addition, fat metabolism is just one part of the equation.
Improving your ability to burn fat doesn't necessarily increase your metabolism overall, nor does it always lead to fat loss.
How to Speed Up Metabolism
Unfortunately, you cannot hack your metabolism to cheat the system and drastically increase your ability to burn calories. No matter what the internet says. However, there are a few things that can affect the speed of your metabolism including your body weight, body fat percentage, diet, and hormones. And the degree to which each impacts your metabolic rate can vary widely.
Here is a breakdown of some of the most celebrated ways to boost metabolism and how effective they really are:
1. Build Muscle Mass
Muscle gain typically means weight gain. And gaining any mass would cause metabolism to increase because it takes more energy to fuel and move a larger object. Though most of us would prefer to gain muscle over fat weight for a variety of reasons.
Muscle is more metabolic than fat, contributing to nearly 20% of your total calorie needs compared to only 3% for body fat (4). The metabolic rate of muscle is about 4.5 to 7.0 calories a pound per day, compared to the fact that supposedly burns only 1 to 3 calories a pound per day (5,6). This would mean an extra 5 pounds of muscle would equal an increase of 22 to 35 calories per day - which sounds small but could add up over time.
Source: Adapted from The Free Obesity ebook
This estimate does not consider the effect on calorie burn during training. Having more muscle might mean you are burning slightly more calories at rest, but it could also mean you are stronger and faster - allowing you to train harder and burn more calories during exercise as well.
In addition, muscle takes up less space than fat, which is why two individuals who weigh the exact same amount but have different body fat percentages can look drastically different.
And most importantly, gaining muscle can sometimes make the number on the scale go up, but this doesn't mean you aren't getting healthier, looking leaner or achieving great results. Taking progress photos, using a tape measure or tracking your body fat percentage might be better suited to show you exactly how well you are doing.
Learn what it takes to build more muscle.
The bottom line: Gaining weight, especially muscle, is likely one of the best approaches to increase your metabolic rate naturally since this directly affects your BMR.
2. Lift Weights
Strength training is one of the best ways to maintain lean muscle and promote muscle growth to improve your body composition - whether you are looking to lose, gain or maintain your weight. In two studies, metabolic rate increased by 7% after 16 and 24 weeks of strength training, likely due to changes in lean mass (7,8).
Lifting weights might also help increase your daily calorie burn, even hours after you've stopped training. Putting wear and tear on your muscles requires a recovery period and this is when positive effects on your metabolism are seen. In one study, increases in metabolism were seen up to 38 hours after strength training (9).
Bottom line: Lifting weights supports muscle mass, which in turn may have some positive effects on the speed of your metabolism, especially if it leads to muscle gain. Plus, the increases in calorie burn from training, although short-lived, may also be an effective approach to weight management.
3. Include HIIT Workouts
Similar to weight training, high-intensity training might also have afterburn effects, referred to as Excess Post-exercise Oxygen Consumption (EPOC) (10,11,12). After exercise, your muscle cells need time to restore normal function and metabolism. And the harder the training, the longer this takes. During this time period, oxygen consumption is increased, which is directly related to calorie burn. Thus, hard training results in a longer recovery period and extended calorie burn, increasing your metabolism during this time.
This explains why a four-minute Tabata workout is able to result in 400 calories burned throughout the day (13).
In addition, HIIT may increase your rate of fat oxidation and support greater fat burning capabilities.
Bottom line: HIIT workouts may be an effective way to temporarily speed up your metabolism and promote more fat loss. However, this approach requires consistent training to be truly beneficial.
4. Eat More Protein
It takes calories to digest calories, also known as the thermogenic effect of food or TEF. And some foods require more calories to digest than others. Protein is thought to be the most thermogenic of all the macros, which is partially why high protein diets are associated with more fat loss (14,15).
- Protein TEF = 20-35% of calories burned through processing
- Carbohydrates TEF = 5-15% of calories burned through processing
- Fat TEF = 0-5% of calories burned through processing
However, most food is eaten in mixed dishes, not as individual macros, and the TEF for mixed meals is somewhere around 10% of your calories consumed. In addition, TEF only represents a small portion of your metabolism (about 10% of your BMR) and an even smaller fraction of your overall calorie burn.
Bottom line: High protein diets are strongly associated with fat loss benefits but are likely not an effective approach to increasing your metabolism since TEF represents such a small part of your overall energy expenditure.
5. Get Enough Sleep
Sleep can impact your metabolism by messing with certain hormones that control your appetite. Lack of sleep has been linked to increases in the hunger hormone ghrelin and decreases in the fat burning hormone leptin (16).
Lack of sleep may also cause you to crave unhealthy foods (17). And fatigue from lack of sleep leads to decreased output all day long and less intense workouts, meaning you are burning fewer calories than when fully energized.
Sleep can also influence nutrient utilization and fat storage. Poor sleep may alter how glucose is metabolized. And not sleeping enough may actually cause you to store more fat, putting a damper on your weight loss efforts (18).
Research suggests that most of us need at least 7 hours of uninterrupted quality sleep each night (19). And playing catch-up on the weekends is not going to counteract the lack of sleep you got all week long.
Bottom line: While alterations in metabolism and hormone function are important, they don't necessarily correspond to the speed of your metabolism. Regardless, getting enough quality sleep could be an effective approach to supporting better weight management and more fat loss.
6. Control Your Stress Levels
Similar to sleep, being in a constant state of stress can do a number on your hormones and how you metabolize your calories.
Chronic stress can lead to increased fat storage, mainly abdominal fat, from excess cortisol production (21,22,23). Cortisol is a hormone designed to help release energy for quick use - like when you are working out or in a “fight or flight” scenario. Continued stress triggers a constant state of fight or flight, and when the energy released is not used, it can be stored as body fat.
High amounts of stress also tend to mean less sleep, leading to changes in appetite-regulating hormones (24). Stress is also linked to poor diet from increased cravings and reduced willpower.
Bottom line: Controlling stress may not make or break the speed of your metabolism, but can certainly help you process your calories more efficiently and manage your diet better overall.
7. Fidget More
Standing more and moving around more throughout the day can also increase your burn. No surprise here, since movement requires calories! For those that have a hard time getting daily exercise in, you may be able to burn a significant amount of calories just from staying lightly active all day.
In one study, those who stood during the day at work burned an additional 174 calories (25). In addition, those who tend to fidget more, tend to expend more energy. Fidgeting may also explain why some people appear to have a faster metabolism.
Bottom line: While these efforts do not directly increase your metabolism, they can tip the calorie equation in your favor by helping you burn more calories throughout the day.
8. Drink Caffeine
Some studies suggest that high caffeine beverages like green tea or coffee can increase metabolism by 4–5% and fat oxidation by 10-16% (26,27,28,29). This is partly why caffeine is often used in popular fat burning supplements.
But additional research suggests that benefits may only be seen in certain populations, such as lean individuals, and that the overall effects, while significant, have little impact on weight loss overall (30,31,32). In other words, the uptick in metabolism doesn’t seem to result in more weight loss.
Bottom line: Coffee and green tea might be a way to give your metabolism a little kick, and when included as part of a calorie controlled diet, may have some minor benefits for weight loss. However, these benefits are not strong enough to outweigh the need for calorie control in the first place.
9. Eat More Fat Burning Foods
Some popular trends like the apple cider vinegar diet, or including spicy foods like cayenne pepper have been touted as special fat burning superfoods. The mechanisms behind a majority of these claims are not well understood, but typically involve optimizing absorption and digestion rates or increasing RMR temporarily through thermogenesis (33,34). And sometimes the positive effects are due to these foods decreasing appetite.
While there is research to suggest certain foods can create a minor uptick in metabolism after eating them, the effects are fairly minimal and short-lived. In addition, the amount of these foods needed to produce significant effects are likely pretty high. Keep in mind that thermogenesis only represents a small portion of BMR (10%), and even with a large upswing, the effects don't stick for more than a few hours - resulting in only tiny increases in calorie burn over 24 hours.
Bottom line: No special food or diet will speed up your metabolism. But this doesn't mean you should discount these foods altogether, especially if they can be included as part of a healthy diet. Just don't count on them melting fat away and igniting a fast burning metabolism on their own.
10. Eat More Frequently
Because digesting food requires calories, some believe that eating more frequently, can help keep your metabolism high. But there isn’t any research to support this claim. And this theory doesn’t make sense when you break it down.
With mixed macro intake, you utilize roughly 10% of the calories you consume to digest your food. This number remains fairly constant across the board no matter how many times you eat. If you ate 2000 calories broken up into three meals or six meals, the thermic effect of your food would still be 200 calories (or 10% of your intake).
Bottom line: Nutrient timing can be important for fitness fueling and recovery, and potentially protein absorption, but outside of these factors it doesn’t impact your metabolism significantly. In fact, you might end up eating more calories overall and gaining weight if you are eating more often.
How to Get a Fast Metabolism
Often times in trendy healthy recommendations, we like to pull out one part of the equation and apply it to the whole story, but altering one piece of your metabolism doesn’t mean you can cheat the whole system. Your body is excellent at compromising and tends to enjoy a state of homeostasis (aka the status quo for you).
There is no magic pill or secret to a fast metabolism. While metabolic processes and the human body can be complex, how your choices affect your metabolism for weight loss are pretty simple. Eat fewer calories from food and burn more calories from exercise to lose body fat. How often you eat or even the types of food you eat don't outweigh this basic principle of your metabolism - calorie control.
So don't rely on gimmicks or certain foods, figure out how many calories you need to eat each day and track your intake consistently. This is the secret! It is the best way to start holding yourself accountable and making meaningful changes in your diet to get real results.
Get started on daily control and food tracking using the free Trifecta app.