If you’re reading this article it is likely that you have been told that your metabolism is
- the reason why you can’t lose weight or conversely
- can be “supercharged” to allow you to burn calories without even trying
Marketers, gurus, and authors use sexy, fantasy land language such as 10 ways to supercharge your metabolism, burn fat fast, boost your metabolic rate, build a fast metabolism, ramp up your metabolism, or master your metabolism to imply that there is something inherently wrong with your metabolism and that by following a set of steps you’ll be able to fix your metabolism or even better yet increase its speed, power, and efficiency.
But what does any of this even mean? What exactly is the definition of a “slow” metabolism or a “broken” metabolism? To the best of my knowledge there is no consensus as to what a “slow” or “fast” or “broken” metabolism even means. Like so many things in the health and wellness industry, these are nothing more than marketing gimmicks and buzzwords designed to sell books with solutions to problems that you probably don’t even have.
While it is true that some obese individuals who have lost a lot of weight (i.e. 100 pounds) undergo adaptive thermogenesis, a condition in which your metabolic rate drops lower than what is expected based on your muscle mass (lean mass), age, and gender, for the most part your metabolic rate is not broken and there is no need to fix it. You also can’t hack your physiology and get “something for nothing” (that is, burn calories at rest without even trying). But, with all that being said, rather than just taking my word on it, I am going to go through the effort of explaining why many of the “solutions” to boosting your metabolic rate simply don’t work or that the return on your investment is so small, that in the grand scheme of things, it is not going to make a difference in your weight loss. If your goal is weight loss, there are tens and even hundreds of things you can do that will better serve your needs than trying to “master your metabolism”.
What is Your Metabolic Rate?
Before we get started, we first need to define metabolic rate and discuss its component parts. You can think of your metabolic rate as being the total number of calories you burn in one 24 hour period (Total Energy Expenditure; TEE) and is the sum of all of the metabolic reactions in the body that cost energy (Figure 1).
Figure 1. The total number of calories you burn each day (Total Energy Expenditure) is the result of the number of calories your body burns at rest to keep you alive (Resting Metabolic Rate), the number of calories you burn during exercise and activities of daily living (Thermic Effect of Activity), and the number of calories required to digest and absorb the food you eat (Thermic Effect of Food) all added together. *Note: Calories are a unit that measures energy. We can measure calories through heat and this is why we use the term “thermic”.
The metabolic reactions that cost energy include the number of calories your body burns at rest to keep you alive (Resting Metabolic Rate), the number of calories you burn during exercise and activities of daily living (Thermic Effect of Activity), and the number of calories required to digest and absorb the food you eat (Thermic Effect of Food) all added together.
Now that we know the components of your metabolic rate, it is also very important to understand that Resting Metabolic Rate (RMR), Thermic Effect of Activity (TEA), and Thermic Effect of Food (TEF) are not weighted equally. RMR accounts for the greatest number of calories burned each day (~60%), whereas TEA and TEF account for lesser amounts (~30% and 10% respectively). Figure 2 illustrates this point.
Figure 2. Components of Total Energy Expenditure (TEE) for a 2000 Calorie Diet. Calories are expressed as a percentage of the overall total and as the absolute (raw) number of calories.
Variance in Metabolic Rate Between Individuals
Figure 2 provides a snapshot of what total energy expenditure might look like in a given individual but it is important to note that the TEE components (RMR, TEA, TEF) can vary drastically between and within individuals. For example, let’s say that you have three individuals. An ultra-distance runner, a software engineer, and a sumo wrestler. The proportion of calories coming from TEA (exercise) is going to be very high, likely far greater than 30% of the calories for the ultra-distance runner as it will not be uncommon for them to run 20 miles/day. The software engineer is stuck behind his/her desk for the vast majority of the day. His/her TEA is likely to be quite low. The sumo wrestler will have a high RMR due to his large body size, a large TEA as they train for several hours each day, and a large TEF as they have to consume upwards of 10,000 calories/day to maintain they body size and support their training.
But these can all change in an instant. If the ultra-runner injures him/herself, their TEA will drastically decrease, if the software engineer decides to start exercising, his/her TEA will drastically increase, and if the sumo wrestler decides he doesn’t want to be a sumo wrestler anymore, than his RMR, TEA, and TEF will all decrease, unless of course he continues eating 10,000 calories/day, then only his TEA will decrease as he is still eating a ton of calories (TEF) and will maintain a large body mass (RMR).
The point I am making here, is that each of the TEE components (RMR, TEA, TEF) can vary between individuals depending on body size, calorie intake, and physical activity and also within individuals depending on what they do and eat on any given day. However, with all that being said, TEE is made up of your RMR, TEA, and TEF components. RMR, TEA, and TEF contain subcomponents, yet whatever you’re talking about, you’re talking about RMR, TEA, and TEF. “Mastering and/or supercharging” your metabolism are meaningless words. Your RMR, TEA, and TEF are actually real, measurable, quantifiable things.
17 Ways to Increase Your Metabolism
In the following 17 Ways to Increase Your Metabolism we will denote each of the methods as falling under the RMR, TEA or TEF categories.
- Increase Your Protein Intake (TEF): protein costs more energy to digest and absorb than fat and carbohydrate. The thermic effect of food is approximately 20-30% of the calories if ingested as protein, 5-10% of the calories ingested as carbohydrate, and 0-3% of the calories ingested as fat. So if you ingest 100 calories of protein, carbohydrate or fat that means that the energy required to digest and absorb those nutrients would be 20-30 calories, 5-10 calories or 0-3 calories. High protein diet advocates will tell you that eating protein burns more calories and this is true; however, it is extremely difficult to make protein the primary macronutrient in your diet at the expense of the other two macronutrients (carbohydrates and fats) because there just aren’t that many pure protein foods. You can eat extremely lean meats (chicken breast and 96/4 ground beef) and low fat cottage cheese but beyond those sources you are more than likely also going to be consuming fat and/or carbohydrate with your protein, thereby diluting out the percentage of your calories from protein.The average American already consumes 15-20% of his/her calories from protein. It is extremely difficult if not borderline impossible to consume more than 40-45% of your calories as protein as real food. Instead you’ll be slugging down a number of protein shakes each day. But let’s say, for the sake of argument that you are consuming a 1400 calorie/day diet for weight loss and increase the protein in your diet from 20% of your calories to 40% of your calories (Table 1).
Table 1. The Thermic Effect of Food (TEF) When Switching from an Average Protein to a High Protein Diet. In Table 1 the Thermic Effect of Food is for protein calories only. *Values based on a 1400 calorie/day diet. **TEF difference of 84 calories between the diet types.
The high protein advocate will tout the fact that you’ve doubled (increased by 100%) the number of calories burned through the TEF of protein. And that’s great, but a doubling of the TEF only adds up to an additional 84 calories, assuming the high end of the TEF for protein (30%) and not the low end (20%). This is also the best case scenario and in it we don’t even consider that on a high protein diet you’re more likely to consume additional fat rather than carbohydrate. Fat has a TEF of 0-3%, that could more than offset the increase in the TEF that you got from increasing your protein intake. Although we’re not going to bore you with any more examples, it is plausible that you could actually have a higher TEF while eating an average protein diet and more carbohydrate than you would eating a higher protein diet and more fat. It is not realistic to think that you’ll be able to eat enough protein to truly be able to take advantage of the thermic effect of protein.
Finally, while I understand that every calorie counts, the annoyance of having to plan, track, and manage your calorie consumption to increase your protein (without going overboard on your fat intake) isn’t worth it and to make matters worse, people who go on high protein diets don’t lose any more weight than individuals going on a high carbohydrate or a high fat diet. To me, eating more protein does not matter in the grand scheme of things and should be of low value to your overall diet goals.
- Eat Small Frequent Meals (TEF): the idea behind eating small frequent meals to boost your metabolism is to prevent, what the health & wellness world has termed “starvation mode”. Starvation mode, as coined by the health & wellness world isn’t a real thing but I have to offer their explanation to be able to debunk their thinking. Starvation mode is what your body enters when you haven’t had food (for an unspecified, poorly defined amount of time). Since your body doesn’t know when and where its next meal is coming from, it decreases its metabolic rate to ensure that you conserve calories.I have written a thorough rebuttal to this type of thinking on one of our sister websites, Why Eating 5-6 Small Meals/Day will Not Boost Your Metabolism but it is worth briefly mentioning here that provided you consume 2000 calories as 3 medium sized meals or 2000 calories as 6 small meals, provided your ratio of protein, fat, and carbohydrate are identical between the two styles of eating, there will be no difference in the number of calories you burn through the TEF. Whether you pay three installments of $100 or six installments of $50, they both add up to $300. The reason that we even went down this nonsensical road is that (some) early studies showed a correlation between eating more meals and weighing less. But as is so often the case, epidemiological studies of that nature do not hold up to the more rigorous testing of randomized controlled trials.
- Eat Breakfast (TEF): breakfast (break fast) follows the same logic as consuming multiple small meals. You don’t want to enter “starvation” mode. There is a fear that your metabolic rate will drop if you don’t eat breakfast. This, unfortunately is another misinterpreted and taken out of context finding. Yes, your metabolic rate will most certainly decrease if you don’t consume any energy for a matter of weeks and months. This is true starvation. Short-term fasting for hours and even a few days is unlikely to significantly affect your metabolic rate. In fact, some studies (here & here), but not all (here), show an INCREASE in metabolic rate after 72 hours of fasting.The National Weight Control Registry , a database of >10,000 individuals who have lost more than 30 pounds and kept it off for one year report that 78% of their members eat breakfast every day. But this also means that 22% do not. It is unlikely that eating breakfast will have a significant impact on your metabolic rate or your weight loss. The counter argument to not eating breakfast is that you will be so hungry at lunch that you’ll overeat at that meal. But the counter argument to the counter argument is that if you didn’t eat breakfast, you didn’t consume calories and now have more calories available in the budget to consume the remainder of the day. The bottom line is, if you are a breakfast eater, eat breakfast, but if you’re not, don’t feel like you are compelled to do so unless it is part of your greater overall strategy.
- Eat Spicy Foods (TEF): a 2001 paper showed there was a negative correlation between chili pepper consumption and body mass index, that is, people who ate chili peppers tended to weigh less than those that did not. The proposed mechanism between chili pepper consumption and reduced body mass is the compound, capsaicin found in the chili peppers that has been shown to decrease appetite and promote feelings of fullness (satiety). Since 2001, there have been several follow-up studies showing no difference in body weight loss between a capsaicin and placebo group over 12 weeks and no difference in weight maintenance during a three month trial of individuals consuming 135 mg capsaicin/day. In the latter study, the group consuming capsaicin had a higher RMR than the placebo group, but if weight loss is your goal, there was no difference between the groups.
- Eat More Calories (TEF): the more calories you consume (specifically protein and carbohydrates) the greater your thermic effect of food (TEF) is going to be. While this is a horrible weight loss strategy, eating more calories will create more digestive and absorptive work and technically will also increase your metabolic rate in the process.
- Eat Negative Calorie Foods (TEF): in the health and wellness world “negative calorie foods” is a term given to foods (mostly fiber) that cost more energy to digest than is obtained through the process of digestion for the body. Fiber is a structural material found in the cell walls of plants and is indigestible by humans. Ruminants such as cattle, sheep, and deer and other herbivores such as horses are able to digest fibrous materials because they have the digestive enzymes and gastrointestinal tract capable of releasing energy from fiber. Humans do not.Some people (falsely) believe that fibrous foods are actually “negative calorie foods” due to the work that it takes to masticate (chew, bite, and grind) these foods and the digestive tract expending energy trying to break down these foods, yet yielding no energy. Celery is viewed as a classic “negative calorie food” but there is no evidence to indicate that eating celery can increase your metabolic rate (beyond the muscular actions of chewing) nor is this a worthwhile weight loss strategy.
- Do Cardio (TEA): there is absolutely no doubt about it that performing cardiovascular exercise (i.e. walking, running, swimming, biking) increases your metabolic rate during said exercise. At rest you are likely burning less than 1.5 calories/minute. During maximal exercise, elite athletes can burn 20 times that (30 calories/minute) and many average Joe’s can burn up to 10 times their resting metabolic rate (15 calories/minute). It must be noted; however, that burning calories is very hard. It is much easier to not consume the calories in the first place than it is to burn them off. For example, it may only take you a matter of minutes to consume over 1000 calories (i.e. McDonald’s Quarter Pounder Meal) but several hours to burn those calories off (i.e. walking 10 miles). People say that you can’t out-exercise a bad diet and they are 100% correct. However, when it comes to temporarily (minutes to hours) elevating your metabolic rate, nothing beats cardiovascular exercise.
- Lift Weights (TEA): lifting weights will also temporarily increase your metabolic rate. When you are lifting weights your metabolic rate is going to be as high as it will ever possibly be. The problem though, is that this burn lasts only a matter of seconds during your repetitions. If you weight train for 30 minutes or perform cardio for 30 minutes at the same general intensity, you will burn more calories doing cardio 100 times out of 100. The muscular contractions utilized during weight training will cost more energy than those performed during aerobic (cardiovascular workouts) because weight training contractions are more powerful than those of aerobic training. However, when you perform a set of 10 weight training repetitions, this will only take you 30-40 seconds, depending on your repetition speed before taking 1-4 minutes of rest between sets. Aerobic training contractions are not as powerful as weight training contractions but they are generally performed continuously for the entirety of the training session.Weight training doesn’t burn all that many calories during a workout but as we will see in item #13 of this list, weight training can increase muscle mass and in turn, now you will be able to perform more work (i.e. lift heavier weights and burn more energy during your workout) and burn more calories at rest as well. Furthermore, depending on the intensity of the exercise, both cardio and weight training can cause an elevated metabolic rate for up to 24 – 48 hours after your last bout of exercise. This is one of the reasons that we say that exercise is medicine and that you need to take it daily. But before you run too far with this idea, I also need to tell you that the exercise needs to be performed at either a really high intensity and/or for a really long duration to elicit this effect. If you lift light to moderately heavy weights (but not heavy weights) or just go for a walk, you will not see this amplification of your metabolic rate over the next 24 hours. This point requires a much more detailed explanation than I am providing here but what I would recommend is to focus on consistency in exercise. Make sure you exercise every day or at least every other day and do something at an intensity that you like. Consistently exercising will raise your metabolic rate and burn more calories than killing yourself with high intensity work one day and taking the next two days off. As a final note here, there are two sure fire ways to get injured. Exercising too intensely or exercising too long (too much duration). Intensity x Duration = Volume. If your volume is too high, or more than your body is ready for, you are going to get hurt. Although you might drastically increase your fitness and metabolic burn, it doesn’t do you any good if you are injured because, again, you will burn far more calories over the course of time being consistent than you will being hurt
- Fidget (TEA): have you ever noticed that some people just can’t seem to sit still? Whether they are tapping their fingers, shaking their leg or twirling their hair, they are moving even when they are sitting. Research has shown that as many as 100 – 200 additional calories/day can be burned while fidgeting. That might sound like great news to some but it seems to me that you’re either a fidgeter or you’re not. People have pointed out to me on numerous occasions that I am shaking my legs in a rhythmic pattern and I don’t even realize it. To the best of my knowledge fidgeting is an unconsciously performed activity that cannot be taught, learned or programmed to an alarm. Although unconsciously (and without effort) burning an additional 100 – 200 calories sounds like an investment worth making I don’t think you can turn yourself into a fidgeter.
- Increase Activities of Daily Living (TEA): activities of daily living (ADLs) are physical activities that you perform every day to maintain good hygiene and live in the twenty first century. Taking a shower, brushing your teeth, and getting dressed for work are all ADLs. They also each require muscle contractions. These contractions do not produce a lot of force and don’t burn a great deal of energy, yet they add up over the course of a day.Fitbit and other activity trackers have really capitalized off both fitness and ADLs as they encourage you to move more to accumulate steps. Some dietitians and other health professionals will encourage you to take the stairs, park at the far end of the grocery store parking lot, take a lap around the grocery store before beginning your shopping, and holding walking meetings……all in the name of getting in a few extra steps. The problem with these strategies is that they only last a matter of a few minutes and burn only a handful of calories. Even if you add up all of these “little activities” you aren’t burning very many calories, yet, the mental accounting of all the things you’ve done over the course of the day to burn calories is actually quite a few tasks and leaves you feeling like you are putting in a tremendous amount of work for very little results. This is why it is my belief that dedicated, programmed exercise is so important to burning calories and losing weight. Getting in a few extra steps here and there isn’t going to make much of a difference.
- Get a Standing Desk/Treadmill Desk (TEA): sitting burns more calories than lying down and standing burns more calories than sitting. Walking slowly burns more calories than standing. Besides the ergonomic benefits (unloading of the spine and maintaining a neutral posture) standing and/or walking slowly at a desk burns more calories than sitting. This is another “mindless” and without much additional effort way of burning calories. There is research to support that individuals who stand and/or slowly walk at their desks are no less productive than their sitting counterparts. From a company’s bottom line, this is great news.While I can support having a standing desk for ergonomic benefits, a treadmill desk seems like a dumb idea to me. The point of having a stand up desk is to unload your spine (sitting actually puts more pressure on your back than does standing). The fact that you can burn additional calories by standing might be another selling point for a standing desk company but to me it’s like telling someone that their chef’s knife is not only good for chopping up vegetables but can be used as a home security system as well. Just because a tool can serve another purpose doesn’t mean that it is the right tool for the job. A security system, good locks, adequate lighting, a guard dog, or even a baseball bat would serve you better than a chef’s knife. I would much rather take a walk outside, where I can get away from work and do some thinking than try to lightly exercise and work at the same time. Not everything needs to be done as efficiently as possible. Maybe I’ll install treadmills in my kitchen while I cook and in my bathroom while I shower, and next to my bed when I fold my clothes. The bottom line is standing at a desk and/or walking slowly at a desk are not ideal ways of burning more calories. Exercise is exercise and work is work. I don’t believe in mixing the two.
- Chew Gum (TEA): I have written an entire blog on chewing gum for burning calories called The Amazing Chewing Gum Diet for Weight Loss and Detoxing, which as a spoiler alert, is a spoof article dedicated to how easily people desperate to lose weight and/or improve their health can be fooled by someone who knows more about the topic than they do and can put together some compelling facts to tell a narrative that supports their product or service. This kind of shit goes on in the health and wellness all over the place and I wish I had time to call them all out but I don’t.Chewing gum burns calories by repeatedly utilizing the jaw muscles. But I ask you this, what is a larger muscle group, your quadriceps (front thigh) or your jaw muscles? And of those two, which can perform more work (i.e. burn more calories)? Your quadriceps, by a mile. In terms of muscle size I can confidently say that your jaw muscles don’t rank in the top 25. You’d be much better off activating your glutes, lats, traps, shoulders, biceps, triceps, quads, hamstrings, calves, abs, low back, and even your forearms before trying to burn calories with such a small muscle group. But again, anything to maximize efficiency and reduce the amount of perceived work you have to do (you can chew gum and do just about anything), and in the process of doing so get something for nothing. It is my opinion that the act of chewing gum to burn calories really isn’t worth it; however, if you constantly have a piece of gum in your mouth, what can you not do? Eat or drink calorie containing foods. While I know that some people will attest otherwise, eating food and chewing gum is, for lack of a better word, gross to me. I’ve known people who can chew tobacco and eat/drink so there are worse (grosser) habits but it is my belief that chewing gum should be used as a food/drink deterrent rather than a means of burning calories.
- Build Muscle (RMR): There is a myth in the fitness community that weight training drastically increases your metabolic rate. The narrative is that resistance training builds muscle, muscle is a highly metabolically active tissue; therefore the more muscle you have the more calories you will burn at rest without even trying. While it is true that resistance training helps build muscle and that muscle is a highly metabolically active tissue (compared to some tissues, i.e. fat), it is very difficult for most people to build muscle through resistance training and muscle only accounts for ~20% of the calories you burn at rest (Figure 3). On a pound for pound basis, your kidneys, heart, brain, and liver are all much more metabolically active than muscle.
Figure 3. Skeletal Muscle Accounts for ~20% of the Calories You Burn at Rest. Skeletal muscle mass is much larger than the kidneys, heart, brain, and liver yet only contributes ~20% of RMR. Data adapted from Wang, Z; 2012 OBESITY.
In a study of men and women undergoing 6 months of 3 day/week full body resistance training, men gained, on average, 3.3 pounds of muscle and women gained 3.1 pounds of muscle. When resting metabolic rate (RMR) was measured after 6-months of resistance training it increased by 9% in men and was virtually unchanged in women. To put this into perspective, if you were religious in your exercise routine and were 100% adherent, that means that you would likely put on 3 pounds of muscle after 6 months and 72 bouts of exercise, of which if you are a male you gained a modest benefit and if you are a woman, you gained no calorie burning benefit at all! Now, to be fair, this is one study of many but my hunch is that the study I am referencing is likely a fairly accurate representation of the effects of resistance training on metabolic rate.
Exercise physiologists like to say that exercise is medicine, because you have to take it every day or at least every other day for it to be effective. The effects of exercise quickly burn off. I’m not suggesting that more muscle would have been gained by exercising more frequently. No, what I am suggesting is that the lasting, chronic effects of exercise, in this case a change in muscle mass and RMR, are not nearly as important as the repeated, calorie burning short-term effects of each individual bout of exercise. It is far more likely that the individuals in this same study burned far more calories during their workouts than any added muscle is going to burn at rest.
- Green Tea and Caffeine (RMR): there is some evidence showing that green tea, caffeine, or a green tea and caffeine mixture can increase energy expenditure 2-4% and as high as 8% in a given twenty-four period. There is also some evidence showing that the ingestion of a green tea and caffeine mixture can lead to a weight loss of up to 5% over the course of 3 months. But before you run out to purchase a green tea/caffeine extract let me say this, I’m not impressed in green tea and/or caffeine as a weight loss therapeutic and I think their benefits are being greatly oversold.There are mountains and mountains of scientific literature studying the effects of green tea/caffeine on metabolic rate and weight loss over time and I think there might be something there, but honestly, I can’t even explain it. It is so nuanced and so complicated that I don’t know how anyone could set up the proper conditions for green tea and/or caffeine to be effective for them in their own lives. For example, some studies show an increase in energy expenditure in lean individuals but not obese individuals. Other studies show an effect in low caffeine consumers (<300 mg/day or about 3 cups of coffee). Many of the studies are in an Asian population, which although valuable, cannot be applied to a black or Caucasian population. It’s really easy for a green tea/caffeine extract company to cite literature to promote the benefits of their products. Like I said, there are mountains of literature out there. But if the literature is so nuanced and so confusing, is the effect even real and if so, will it play a significant role in your life. It is my opinion that purchasing these extracts or taking up a green tea/caffeine habit for the purpose of trying to increase your metabolic rate or lose weight, is an effort that can be spent (literally and figuratively) better elsewhere. Finally, I will let you in on a bias that I have that applies to these studies (and others as well). Researchers’ careers are built on studying certain things, in this case green tea and caffeine. Of course they are going to oversell the importance and the potential of green tea and caffeine on a whole host of health issues. If they can’t sell its potential importance, they aren’t going to get funded and that means no more studies and no more career. The researchers will stumble upon certain data that is statistically significantly different (p < 0.05) but meaningless in the real world outside of their academic bubble. I’m not the first one to make this criticism of academics and it pains me to have to admit these things (with me being a former academic and my wife and friends academics) but far too often their “findings” are just another way to promote the benefits of their studies and the need for more studies, or as an old advisor of mine used to joke with me, for their job security. I don’t mean to be disrespectful or ungrateful but I see very little value in studying green tea and/or caffeine and I don’t see any point in you going out of your way to consume it for metabolic rate or weight loss benefits.
- Heat the Body Up (RMR): we’ve all seen that guy in the gym wearing a hooded sweatshirt, hood up, just pouring sweat while climbing the stair master. People oftentimes mistakenly equate sweating with burning calories but sweating doesn’t burn calories, muscular contractions burn calories. Muscular contractions are about 40% efficient. That means that 40% of the energy used during a contraction (ATP) produces force/work whereas the other 60% of that energy is lost as heat.Repeated muscular contractions not only burn a lot of energy but they also produce a lot of heat. This heat is then transferred from the working muscle to the blood and in turn when this warmed blood reaches the part of the brain known as the hypothalamus, it sends a signal to activate your sweat glands in an effort to cool the body through the evaporation of sweat.But if I ask you this, does sitting in a sauna burn more calories than sitting at room temperature? Much to my surprise, yes, it does. In a 2019 study men undergoing four 10 minute bouts in a dry sauna (90 degrees Fahrenheit), separated by four 10 minute bouts at room temperature nearly doubled their energy expenditure (73 calories to 131 calories) from the first sauna bout to the fourth sauna bout. The participants also lost 1.4 pounds on average, of which ~1.10 pounds was water weight. So, it is plausible that hooded sweatshirt, stair master guy, may actually be burning more calories than if he were wearing shorts and a t-shirt. With that being said, I think we still need to consider a) how many additional calories we will burn through an excessive heating of the body and b) will exercising in a sweat suit diminish the level of enjoyment you have while exercising? Because if you don’t enjoy the exercise, you’re not going to be eager to do it again. And consistency above all else is king for burning calories over the course of time. I have to admit that I’ve always made fun of sweat suit guy but provided you’re adequately hydrating and don’t mind being bathed in sweat, it may be worth it to you. For the record, I’m not recommending you do this but there actually may be some merit to it.
- Cold Exposure (RMR): there are two ways in which cold exposure can increase your metabolic rate. One is through the induction of shivering and the other is through the stimulation of brown fat. In a 1988 study, Matrineau & Jacobs found that metabolic rate increases, on average, up to 3.5 times that of resting when subjects were asked to sit in a cold water (64.4 degrees Fahrenheit) bath for 90 minutes. In this study shivering was induced after five minutes of cold water immersion and resulted in an increase in metabolic rate to that of 27% of their maximal capacity (if they were to all out sprint).To put this into perspective, if we do some quick calculations, their subjects were burning 1.375 calories at rest for 90 minutes resulting in 124 calories being burned at rest. By comparison, if their metabolic rate increased 3.5 fold during cold water immersion this means they would have burned 433 calories for 90 minutes. 433 – 124 = 309. They burned an additional 309 calories through shivering! I can imagine this wasn’t all that enjoyable but they did actually get something for nothing in terms of burning calories and not trying.Now to brown fat. Traditionally, it was believed that fat tissue (adipose tissue) was a non-metabolically active, storage tissue for dietary fat and excess calories. Since this tissue is white (sometimes yellowish) in nature, it was called white adipose tissue. We now know that white adipose tissue isn’t just an inert storage facility for the fat and extra calories you eat but is actually a highly active endocrine organ (secretes hormones) that communicates with virtually every system of the body. We have also recently found out that white adipose tissue isn’t the only type of fat cell/tissue. There are also brown adipocytes. We’ve known for quite some time that brown adipocytes are quite prevalent in babies but we always thought they disappeared as we aged and became insignificant as we grew into our adult bodies. We know now this to also be untrue. It is thought that infants have so many brown adipocytes because brown adipocytes are able to produce heat and keep them warm (through a mechanism we will not discuss here). As we age and grow into adults we are better able to regulate our body temperatures and hence there is no longer a demand for brown adipocytes and they essentially go away. But this isn’t the case. In fact, adults do still have some brown adipocytes and in a 2012 study, Ouellet and colleagues found that by exposing humans to cold conditions and dropping their skin temperature down to 92 degrees (from 98.6), they were able to “activate” their brown fat stores and increase the subjects’ metabolic rates by 1.8 times, which during a three hour period equated to an additional 250 calories being burned. Impressively, the researchers were able to cool the subjects to be cold enough to activate brown fat without cooling them so much to induce shivering and the activation of calorie burning through skeletal muscle contractions. The study of brown adipose tissue is currently a hot research topic and we are learning more about it every day. Volumes can be written on it but here’s a summary of what we know about it now. Working in cold conditions or sleeping in cold conditions both increase the amount of brown adipose tissue in the human body. Acute exposure to cold increases the activity of brown adipose tissue to generate heat to help keep us warm. However, during thermoneutral conditions (i.e. room temperature; comfortable conditions) brown adipose tissue is not activated because it is not needed (i.e. we are already warm). So, while it is interesting to note that we can increase the amount of brown adipose tissue and we can activate it at will with cold exposure, during temperature controlled, comfortable, thermoneutral conditions, it is not going to burn additional calories for us. My wife and I will sometimes joke that when our house is cold that we are activating our brown adipose tissue. But that’s all this is, a joke. While it is super interesting from a scientific standpoint, mild decreases in the temperature of your house or working conditions aren’t going to lead to meaningful changes in your metabolic rate. Your house or working conditions simply are not going to be cold enough to be effective in activating brown adipose tissue.
- Increase Body Mass (RMR): there is a clear, positive relationship between body size and metabolic rate. The larger you are, the higher your metabolic rate is. As we saw in Figure 3, the bulk of your metabolic rate is due to your brain, liver, kidneys, heart, and skeletal muscle. With the exception of your brain, if your body mass increases so does the size of your liver, kidneys, heart, and skeletal muscle. If you take a MRI to measure the organ size of a sumo wrestler and an individual smaller than a sumo wrestler, you will see a large difference in organ size. This makes perfect sense because the sumo wrestler has more tissue mass to maintain and support. The heart, liver, and kidneys have more work to do. If the sumo wrestler retires and loses weight, the size of those organs will decrease and the number of calories burned by those organs will also decrease as they have less work to do because there is less mass/tissue to support.There is a common myth in the health & wellness world that if you overeat you are only going to gain fat. This is not true. Provided the amount of protein you consume is at least 15% of your total calories, you will gain lean tissue (i.e. muscle) and fat mass. Now, if all of your excess calories came from Coca Cola, then it is possible that you wouldn’t gain any lean mass. But this would take some specialized effort and represents a very small portion of the population. It is far more likely that the person consuming too many Coca Colas is also consuming too much fat and protein.If you want to become a calorie burning machine, increase your body mass by consuming excess calories. Of course this is the opposite of what most of us want to do. We don’t want to bulk up to become NFL lineman, we want to slim down, so increasing your body mass to increase your metabolic rate probably isn’t in your best interest.
While there are many proposed ways to “boost” and “supercharge” your metabolism, the majority of them either do not work or are very impractical. Table 2 below provides a summary of the 17 solutions for increasing your metabolic rate, the category of metabolism under which it falls, the proposed mechanism of action, the general level of effectiveness of each solution, and the practicality of employing them into your life.
Table 2. A summary of the 17 solutions for increasing your metabolic rate, the category of metabolism under which it falls, the proposed mechanism of action, the general level of effectiveness of each solution, and the practicality of employing them into your life.
If you read anything that I write and understand my nutrition philosophy, it is centered around two major tenets. Meal plan, meal plan, meal plan, and control your food environment. It is my opinion that your metabolism kind of is what it is. Can you make small tweaks and changes? Sure, but more often than not, these small tweaks and changes are far more effort than meal planning and controlling your food environment are going to be and are going to yield far less robust results for all of your efforts.
Now to be fair, you could increase the protein in your diet, do cardio and lift weights while wearing a winter jacket to increase your body temperature during your workout, sit in a sauna, set a timer on your phone or tap your feet to a metronome to increase your fidgeting, incorporate more activities of daily living such as taking the stairs, getting a standing and/or treadmill desk, chew copious amounts of gum, build muscle through weight training, drink excessive amounts of green tea and/caffeine, and sleep in a very cold room without bed sheets to induce and activate brown fat. All of these efforts would add up and again, to be fair, no one has every studied the combination of these strategies. We’ve for the most part studied these strategies in isolation but not in a combination.
I don’t particularly like meal planning and I don’t like cooking but the alternative to these activities is poor health or an insane person’s regimen of sleeping in the cold and working out in a winter jacket.
A Final Word
Let’s say that I give you $10,000 to invest in an online savings account or CD and your interest rate is 1.30%. This means, that you’ll be earning about $0.36/day or about $10.80/month. While I know that every bit helps, you’re never going to make any money or retire on such a small return on your investment. Netflix alone is $12.99 month. A six pack of craft beer is oftentimes more than $10.80. A men’s haircut is well over $20. There are endless numbers of things that we all spend money on that, if we cut back on, would yield us a greater return on our investment than trying to get something for free by opening an online savings account or CD. Giving up Netflix, drinking less beer or getting fewer haircuts aren’t fun to do, they are sacrifices but that’s what it takes to save money. And the same can be said about losing weight. It is going to take some sacrifice. Because nothing in this life is free and neither is losing weight by boosting your metabolism. Your metabolism is not broken, does not need fixing, and trying to hack it is a waste of your precious time, energy, and resources.