Looking to jump start your metabolism but feeling worn out and over-spent? Do you keep ending up right back where you started after a only few weeks of trying something new? We are inundated with lists, articles, images, videos and talk shows promoting quick fixes and simple tricks to boost metabolism. Rankings of "superfoods" and extracts claiming to kick your metabolism into high gear plaster our physical and virtual environments. These advertisements and articles appear alongside social media feeds, pop-up during Internet searches and get covered as news stories in the health section of online news feeds.
Topics once debated among researchers through peer-reviewed journal articles, documented correspondence and scientific meetings now reach the public within hours of being available online. News articles report about pieces and parts of nutrition and health-related studies, often times before the print version of the full articles are available. While some full versions of primary research articles are available to the general public, most are not. This leaves most readers forced to trust the reporting of the journalist. In some cases this is okay; in others it is not. We have lost an important level of scientific discussion and discovery that used to happen. This loss contributes to the massive influx of seemingly conflicting information bombarding consumers on a daily basis, particularly when it comes to topics related to nutrition.
Frequently, the very act of intentionally altering an eating pattern, adding variety in an exercise routine or increasing self-awareness with regard to eating and/or exercising leads to initial results. The challenge, as many of us know, is sustainability. The reality is there is no quick fix or magic pill. There is no one simple trick. I'm still not clear why some foods are suddenly "super." When it comes to metabolic rate and what you can do to maximize it, there a few simple truths that are important keep in mind.
What is metabolism, metabolic rate, and total energy expenditure?
- Metabolism refers to processes within the body that release energy. In terms of nutrition, body weight and body composition, we most commonly measure the released energy in terms of kilocalories (kcals) expended.
- We only get energy from dietary sources that provide kcals (carbohydrates, proteins, fats). Vitamins and minerals do not themselves provide energy. They do not yield kilocalories.
- Alcohol also provides kcals. I am put it here as its own bullet because it is not a nutrient; we do not need alcohol to perform any essential functions in the body. If consumed, alcohol does provide energy in the form of kcals.
- When we consume more energy (kcals) than we need, we store the energy. We store most of this excess energy as fat.
- Metabolic rate refers to the energy expended during a specific period of time such as minutes, hours, or a day. It is common to measure this in terms of kilocalories per hour (kcal/hr).
- Total Energy Expenditure (TEE) is the sum of all energy releasing processes in the body. TEE can be summarized in the following equation:
- TEE = BM + TEA + TEF + AT
- BM means basal betabolism
- TEA means thermic effect of activity
- TEF means thermic effect of food
- AT means adaptive thermogenesis
- Basal metabolism (BM) refers to the energy costs associated with maintaining the body when it is at complete rest.
- Basal metabolism includes the support of basic body functions such as resting heart rate, basic respiratory function, making proteins, forming urine, etc.
- BM refers to a nonactive state, when fasted (at least 10 hours after a meal), and an in a temperature controlled environment that is not too cold or too warm.
- Basal Metabolic Rate (BMR) is the measurement of BM within a specified time frame.
- Resting Metabolic Rate (RMR) differs from basal metabolic rate (BMR). RMR can be quantified between meals (does not require the fasted state) This measure is more readily attainable than the BMR and it is more common to have your RMR assessed than BMR.
- RMR contributes 65% to 75% of TEE
- If BMR value is used, contribution is 50% to 65% of TEE
- TEA is thermic effect of activity
- Includes activities ranging from exercise to maintaining posture to shivering. Sometimes, these are classified in two ways:
- Deliberate, obvious activity like exercise
- Nonexercise activity thermogenesis (NEAT)
- Whenever caloric needs are determined on an individual basis, activity factors are included to account for TEA. Based on a person's activity level, the activity factor is multiplied to the calculated BMR or resting metabolic rate (RMR).
- TEF is thermic effect of food
- This is considered the cost or tax associated with digestion, absorption, processing, and storing food and other digested compounds.
- We estimate that TEF contributes an overall average of 10% to TEE. While there are some differences among foods, it averages out to 10% overall and the differences become negligible.
- TEF contribution peaks about 1 hour after a meal.
- AT is adaptive thermogenesis
- The human body maintains an average constant temperature during health and adapts to maintain that core temperature.
- The contribution of AT to TEE is greater in infants than adults.
- BMR is a calculation based on age, gender and height. If you would like to see what your BMR is, you can use this BMR Calculator. This site refers to BMR as BEE (which is common).
- Unless you are seriously injured, select "none" for your stress factor.
- Unless you are not, select "ambulatory."
- This does not include an activity factor.
- Note the units of measure
- Height must be in inches or cm
- Multiply feet by 12 to convert from feet to inches (5'6" = 5'x12 + 6" = 66 inches)
- Weight must be in pounds (lbs) or kilograms (kg).
- Convert from lbs to kg, divide weight in lbs by 2.2 (138 lbs / 2.2 = 62.7 kg)
- Age must be in months (40 years + 3 months = 483 months)
- If you would like to see what happens as you age, plug in increasingly older and decreasingly younger ages and see how that impacts your BMR.
- What to do with this information about BMR
- Your BMR makes up 50-65% of your total energy expenditure needs. That is at least half. If your calculated BMR is 1200 kcals, then 1200 kcals is your starting point for what your basic caloric needs are without any physical activity factored in.
How can I increase my metabolic rate?
The number one thing that can effectively increase basal metabolic rate (assuming that there is no underlying metabolic disease that has been or can be diagnosed by a physician) is to increase the proportion of muscle mass in the body in relation to fat mass.
- Strength training, resistance training and weight lifting along with cardiovascular exercise.
- As age increases, BMR decreases. Increasing the percent of your body that is muscle mass (lean mass) and decreasing the percent that is fat (fat mass) is something that can modify the age-slowing impact on BMR.
- Why does increasing muscle mass and decreasing fat mass increase BMR?
- Fat tissue is very thrifty. Our bodies were designed to store fat in case we need it later. Energy stored in fat provides an accessible fuel source for the body when it is needed. However, many of us find that we end up with a bit more energy stored than we may actually need. Fat cells (adipocytes) are very good at storing fat and they do this with very little energetic cost to the body during inactive times (when we are at rest).
- Skeletal muscle is different from fat. It requires energy to support protein turnover. In other words, there is a cost associated with maintaining skeletal muscle. The more skeletal muscle there is, the more protein turnover needs to be supported. This requires metabolic energy and this is why more lean mass increases BMR.
- Metabolic energy comes from energy yielding sources, namely carbohydrates and fats.
- Dietary protein gives the body the building blocks to build more protein; it provides the essential amino acids needed to build more protein. Unlike dietary carbohydrates and fat whose role is to provide the body with energy, the main job of dietary protein is to provide the body with amino acids. The body will only use protein for energy if the diet is devoid of carbohydrates and/or fats, which is not at all ideal.
- Working muscle (weight lifting and strength training) builds muscle. Eating protein does not build muscle.
- As I said in the beginning, there are lists out there describing tips and tricks suggesting things you can do to kick-start your metabolism or influence your metabolic rate. At the end of the day, the best thing you can do to increase your metabolic rate is to increase the ratio of muscle mass to fat mass.
What about food and sleep?
As mentioned above, the number one thing healthy adults can do to increase BMR is to increase muscle mass. To have a long-term and sustainable impact, it is most effective to incorporate safe exercise with healthy eating and regular sleep.
Food
- Eat a colorful diet. I mean this literally. A diet with lots of color reflects variety. Variety in the diet means that you are bringing in foods that provide phytochemicals (plant chemicals) from many different sources. That is a good thing.
- Select foods that are rich in whole grains, fiber, fruits and vegetables, lean sources of protein, low in cholesterol and that are moderate in portion sizes
- MyPlate has useful information about meal planning for all ages, choosing variety, and it provides a link to SuperTracker.
- SuperTracker is a free online resource that allows you to do nutrient analysis of the foods you eat. It will also calculate the calories you need based on your age, gender and activity level. It can be a bit tedious to find the foods you are looking for, but it is fun and provides a lot useful information.
- Pick moderate portion sizes.
- Sleep is important and 6-8 hours of sleep per day is recommended (technically, naps do count).
- If you feel worn down, fatigued or sluggish, it is worth taking a look at your sleep patterns and habits.
- It is also important to discuss these concerns with your physician.
Body weight vs. body composition
- Body Mass Index (BMI) is a measurement that reflects body fatness in relation to height and weight.
- BMI is a reasonable reflection of body fatness for most people.
- BMI Calculator
- BMI, however, is limited for some people. It is not an appropriate tool for some athletes and certain other people if they have a very high percent of lean mass (muscle mass) and very low percent of fat mass (body fat). A classic example is when a very fit NFL player has a BMI classification of obese.
A healthy body weight
- A healthy body weight is one at which your heart rate, blood pressure, lipid profiles (HDL, LDL, total cholesterol), blood glucose (blood sugar) are good. Metabolic health is what we strive for and this is the true marker of health.
- A healthy body weight is one at which you feel good and are not left feeling hungry all of the time.
- A healthy body weight is very individual.
- It is quite unlikely that your healthy body weight is the number you have in your head. I encourage you to consider that your healthy body weight is more a metabolic state of being than a number.
- Healthy Body Weight
Some things to watch out for...
- Too good to be true
- Restrictive diets
- Lists of "do's" and "don'ts", especially if they cost money
- Promises to remove or lose fat from a specific area of the body (my personal favorite are promises to melt belly fat away)
- Promises that you can lose weight, melt fat, and/or speed up your metabolism without ever stepping foot into the gym
- Promises of weight loss and/or increased metabolism without making any changes in your life.
