A Matter of Metabolism
Weight Loss comes down to Resting Metabolism Rate/Basal Metabolism Rate combined with physical training and balanced nutrition. All humans expend energy in three ways: through the resting metabolic rate, physical activity, and digesting and metabolizing food.
Your body burns calories all day and night whether lying in bed reading your favorite magazine, eating breakfast, working at your desk, having drinks with friends after work, or during sleep and recovery. This process represents the energy expended by the body to maintain life and normal body functions. Your metabolic furnace burns calories as a form of maintenance to keep your body warm, your lungs breathing, your heart circulating blood and your brain active. This process is called your metabolism rate. How you decide to manage or should I say manipulate your metabolism will determine whether you lose or gain weight.
Your body burns calories during daily activity and the act of sleep, when your body is simply recovering from the day. This is referred to as your resting metabolism rate (RMR), which continues to burn calories through the function of digestion, circulation and respiration, and movement. The largest number of calories expended by most people (except for athletes) is from the Resting Metabolic Rate during sleep (recovery).
Your RMR varies up to 20 – 30 percent among people of the same age, sex and body weight – yet 80 percent of this variation is due to differences in body composition (body mass). For example, the energy requirements for men and women vary; taller people need proportionately more energy than shorter people to balance their energy budgets because a greater surface allows more energy to escape as heat. Older people tend to need less than younger people due to slower metabolism and reduced muscle mass, which occur due to reduced activity levels. And morbidly obese individuals have a higher RMR base solely on body mass verses a thin person. On average, energy needs diminish by 5 percent per decade beyond the 30 years of age. Heredity may account for as much as 40 percent of this variation.
So how can we boost our metabolism? A majority of our calories are being burnt during sleep hours (rest and recovery), then we can manipulate other areas of our life like activity level (exercise), and the amount of calories (energy) we consume (portion control). You can’t really speed up your basal metabolism rate very much unless you amplify your energy expenditure on regular bases. If you do, you will start to spend more calories each and every day, day after day, which will require more recovery, which in turn increases your BMR. Lean body mass is more metabolically active than fat tissue. Yet the more body mass you posses the more calories you will need to support that mass. For example the bigger the home you own the more time and money it will take to maintain. So it is totally possible that a 350-pound person will require more calories and have a higher metabolism than his smaller leaner counterpart. And when talking about voluntary activities, the heavier the weight of the body, the more calories that body expends during activities.
Research Surrounding Consumption of Food (Calories)
There is an ongoing controversy as to whether obese individuals eat more than their leaner counterparts. Much of the research in this area points to the concept of “diet resistant subject”. What that means is subjects studied were found to be underestimating food intake by about 50 percent and overestimating physical activity by 33 percent.
Consumption factoid: Many researchers have come to the conclusion that obese people tend to expend and therefore eat about 400-500 Calories more on an average each day. And there daily energy expenditure was more than 400 Calories higher among the obese women, with half of this due to their higher metabolic rate. Because a higher mass means higher resting metabolism regarded to maintain that mass.
A typical physical training approach involves measuring your current body composition and adjusting your calories for weight loss. Let’s say my client wants to reduce their body fat by 10%. I would establish a baseline for my client’s weight and the percentage of body fat. I would encourage a balanced diet and exercise. If we know that a pound of fat is 3,500 calories, it would be reasonable to lose no more than 2 lbs. a week. If you’re losing more than 2 lbs. a week, you’re likely losing some muscle and water weight along the way. Yet if you are working out, the more weight you lose the less body fat you will have.
In general, trainers tend to structure their sessions around various types of weight training protocols while simply recommending that their client do cardio three to five times a week. I am afraid that I am guilty of the same structure in my practice. I train my client with great care watching their form as they execute various exercises, supervising and moving them from exercise to exercise with great precision depending on whether it is a 30, 45, or 60 minute session. This seems logical, since magazine after magazine bombards Americans with the images and the promise that lifting weight is the quickest way to improve their physical appearance, strength gains, postural alignment, balance, coordination, reaction time, bone density, and reduction in body fat while increasing lean muscle tissue. But generally the cardiovascular component doesn’t seem to get done efficiently or with enough intensity. It is absolutely as important to maintain your heart health, as it is to nurture your lean muscle tissue. Ultimately it is more important to maintain the functionality of the heart, lungs, and circulatory system. Actually, most clients hate the cardio aspect of their workout and prefer to believe that lean muscle tissue will provide them that sleek, high performance body. The biggest problem with this mindset rests with the lack of supervision during cardio training. The average person just isn’t focused enough if left to his or her own devices; typically they are listening to their iPod, reading a magazine or book, or watching a show. Research has made a case over and over that exercise intensity, frequency, consistency and volume have a lot to do with cardiovascular fitness. The benefit of executing a minimal twenty minutes of continuous cardio on the treadmill, elliptical or climber depends on the executed.
Any cardiovascular exercise performed at 55-85 percent of ones’ target heart rate will decrease the risk for cardiovascular disease, diabetes, and obesity. Many health studies point to cardiovascular disease being the number one cause of death for both men and women.
If you are serious about the prevention, treatment, and control of many life style diseases (hypertension, diabetes, high blood pressure and high cholesterol) the American College of Sports Medicine (ACSM), recommends that exercise programs emphasis aerobic activities while being supplemented by weight training. And while weight training certainly has proven to have many benefits, cardiovascular fitness wins hands down at improving overall health, decreasing obesity (if the consumption of calories is being managed) and helping prevent disease. If I could assure my client would devote 30 – 45 minutes to the cardio component of an exercise prescription, not only would their waistline shrink, they would be far more successful during their weight training session.
The general public is under the impression that every pound of muscle will burn off up to 50 extra calories a day just sitting around. So they want to maximize their muscle gain to allow them maximum calorie utilization, sounds good but it’s more of a marketing speech delivered by the training industry. The strength-training component of fitness has and still is a major motivational sales tool among fitness professionals seeking to sign up a new client needing to decrease their body fat and lose weight. It would be a real disappointment if I told you that the effort to build and maintain muscle mass in hopes of increasing your resting metabolism rate (RMR), which theoretically increases the amount of calories expended at rest, has been a waste. I wouldn’t go as far as to say any fitness activity is a waste yet I would want you to understand that it isn’t the key to weight loss. In fact, the debate surrounding the effects of strength training could have serious repercussions for the fitness industry. Years of research have provided endless ammunition for why individuals need to exercise to prevent disease caused by a sedentary lifestyle.
The Reality Surrounding Metabolism
The question that should be asked is whether or not strength training actually increases a person’s metabolism rate, and whether that increase is sufficient enough to justify trainers to recommend regular strength training programs as a means to weight loss.
I can absolutely recommend strength training for lean (fat free) muscle preservation. The problem rests with the fact that there is a misconception that every pound of muscle you build will need to burn off up to 50 extra calories a day, when in fact each pound of fat free muscle has been calculated to use about 8 to 15 calories per day. In the grand scheme of fitness, this calorie burn is rather negligible when you consider losing one pound; you must burn a 3,500-calorie deficit. Research just doesn’t support the use of weight training for weight loss. It can be accurately stated that metabolic rate is acutely (temporarily) elevated after a workout and that the intensity of the exercise can sustain a longer post workout metabolism rate which requires the use of additional calories. What matters in the landscape of weight management is how metabolically active is your muscle because resting metabolism rate doesn’t really differ between people who are fat or lean. In either case, it is reported that both groups average about 200 to 250 milliliters of oxygen per minute or about 3.5 milliliters of oxygen per kilogram of body mass per minute, which is equal to 1 MET (metabolic equivalent). And this my friend equates to about 9 to 11 calories per pound of body mass per day. This is why heavier people have a higher resting metabolism rate. It simply comes down to the fact they have more mass to support than a thin person.
Factoid: The MET system is a simplified process for classifying physical activities using metabolic equivalents, or METS. One MET is equal to the resting oxygen consumption, which is approximately 3.5 milliliters of oxygen per kilogram of body weight per minute (3.5ml/kg/min).
Factoid: Think of your body as a home with X number of square feet, than consider how much water, electricity, heating and air is required to run that home. The more square footage the utilities will cost.
As my clients lose weight (or in a negative energy balance), their resting metabolism rate decreases despite the weight training.
No research has documented that resting metabolism rate is maintained, or increased, when people achieve negative energy balance.
Professionally, I cannot in good conscious recommend that weight training in itself will produce a need for more calories at rest and hence weight loss. I can only imagine how many individuals are now saying, “Great, then why am I working out” or “wow I really don’t need to work out any more”, then there are others who will want to argue the facts surrounding fat loss and weight training. Just remember that cardiovascular activities are designed for heart health while muscular endurance and strength provides a laundry list of internal benefits for the musculoskeletal system, physical capacity, appearance and metabolism.
Factoid: Muscle is very active tissue with higher energy (calorie) needs for maintenance and rebuilding processes than fat tissue. Even when we are asleep, our skeletal muscles demand 25% or more of our caloric intake (see my article “Calculating your Metabolism Part I”).
Let me tell you what research does say about training and your resting metabolism rate. What we know is that your total daily caloric expenditure (RMR) increases in response to aerobic or weight training. It also notes that the resting metabolism rate is not significantly different between individuals with different fitness levels and this fact is independent of people who weight train. Of course, as a professional I encourage the development of lean muscle tissue and reduction of body fat because as stated additional muscle mass with aerobic intensity combined with a longer duration elevates your metabolism for a longer period of time which translates into more calories utilized and subsequently weight loss when combined with an appropriate energy intake (food). But when comparing workouts of equal duration, cardio uses more calories hands down than does weight training even during the recovery period. Apparently this is no great after burn of calories, as marketed by the personal training realm. Even with all the athletic facilities, fitness magazines, DVDs, health foods, organic foods, supplements and equipment that calculate your daily caloric intake, we are still fatter than ever (7 out of 10 people are obese).
Then of course your industry’s leading epidemiologists’ state that when you replace fat tissue with lean muscle mass, you may not weigh less but you will expend more calories at rest. In other words we are back to the myth that resting metabolism requires 50 calories a day to maintain 1 pound of muscle. Then of course world renowned Claude Bouchard Ph.D. who’s research focuses on the genetics of obesity at the Pennington Bio Medical Research Center has been quoted as saying, “Skeletal muscle burns about 13 calories per kilogram (2.2 kilograms = 1pound) of body weight over 24 hours when a person is at rest”. This translates into Bouchard ascribing resting metabolism at less than 6 calories per 1 pound per day. His example points to the absolute fact by saying if a 165 lb. male has about 62 lbs. of skeletal muscle, that accounts for approximately 22 percent of his resting metabolism (1,600 calories RM X 22 percent used by muscles = 352 calories used by muscles divided by 62 pounds of muscle = 5.7 calories per pound by muscle per day at rest). Bottom line to this equation is that weight lifting has virtually no effect on resting metabolism.
Essentially, most studies that do not involve low-calorie diets show significant increases in muscle mass and resting metabolic rate after 10 weeks of sensible strength training. Remember, if you accrue more body mass you will create the need for a higher metabolic rate to maintain that mass yet that increase doesn’t correlate to weight loss. I suspect that when you strength train, all your trained muscle tissue has a higher resting metabolic rate than it had prior to the exercise program. It would be impossible to claim otherwise. Like the theory of chaos, everything that happens in life affects everything else in some way. How much no one can really agree upon.
Factoid: Trained muscle tissue has a higher metabolic rate than untrained muscle tissue
The actual studies point to the fact that a standard program of progressive resistance exercise can increase lean muscle weight by 3.0 to 3.5 pounds and because of the new mass the resting metabolic rate increases by 6.8 to 7.7 percent after three to four months of regular training. So it is true that strength training has a significant elevating effect on resting metabolic rate and is a beneficial form of exercise for increasing daily caloric expenditure and enhancing fat loss but not weight loss. And to really see weight reduction, you must add in daily cardiovascular exercise (aerobic activity) along with a reduction in caloric intake.
Marketing an Industry to the Masses
The fitness industry bases the idea of caloric burn on research that indicates that regular strength training elicits an increase rate of muscle protein synthesis, which in turn elevates the energy that tissue needs to operate throughout a given day. We now know that instead of up to 50 calories per pound in actuality we can validate muscle tissue metabolism is really around l.5 calories per pound per day and that this statistic multiplied by all of the trained muscle gives way to a significantly higher resting metabolism rate. This is more reasonable then trying to suggest that new muscle tissue uses a flat 35 to 50 calories per pound per day, or that trained skeletal muscle still uses only 5.7 calories per pound per day.
Thermic Effect of Food
The Thermic Effect of food (TEF) is the increase in energy expenditure above the Resting Metabolism Rate that can be measured for several hours after a meal. This refers to our body’s ability to digest, absorb, transport, metabolize and store the food eaten. The TEF is higher after carbohydrates and protein meals than it is after a fatty meal. The average person’s TEF is about 7 to 10 percent of total ingested calories, or about 120-170 calories per day for women and about 180 to 260 calories per day for men. For example, after a meal containing 800 calories, the body will use approximately 56 to 80 calories just to breakdown and process the meal.
How many calories did I consume at this meal?
Jeff had a late morning snack consisting of a granola cookie. His treat has 20 g of carbohydrates, 3 g of fat, 2 g of protein and 150 m of sodium. How many kcal did Jeff consume?
20 g of carbohydrates X 4 kcal/gram = 80 kcal
3 g of fat X 9 kcal/gram =27 kcal
2 g of protein X 4 kcal/gram = 8 kcal
Sodium represents 0% of daily value
Total of consumption: 115 total calories
The Notion of Activity Level
At some point, you want to determine total calories, which can be affected by activity level. This gets tricky, because everyone believes they are very active, so I ask my clients not to add any additional calories until they can demonstrate the capacity to lose weight. Then, if they are actually losing weight due to their current level of activity, they may add 10 percent on to their total calorie intake, if they are still losing weight then they can add another 10 percent and again if needed but the normal range varies from 10-30 percent unless you’re Lance Armstrong doing the Tour de France. Don’t worry you’ll not need to worry about this level of input – output.
I am asked continually questions regarding the notion of total calories verses form of calories (protein, carbohydrates, and fat). As well as, how does one accurately figure out how many calories are needed on a daily basis to lose weight or body fat without sacrificing muscle?
Q: So what is more important, your total calories or the type of calories (protein, carbs, or fat) you consume?
A: Actually the total number of calories you eat, as opposed to the type of calories you eat. The composition is a consideration yet eating fewer calories than you expend during a day is absolutely key to losing weight and in turn body fat. The untold story is that everyone absorbs and utilizes calories differently due to genetics, sex, age, food preparation, life style, activity level, and many more factors.
Hands down, total calories are far more important than the types of calories you put in your body, if you looking solely at energy in – energy out. This is where the tricky part comes into play, if you suffer from metabolic syndrome, insulin resistant, or elevated blood sugar the composition is absolutely important to your energy, health and wellness. Yet for the average person, eating fewer calories then you expend during the day is a corner stone to weight loss and in turn reducing body fat.
Great, right, glad to know all this info but you still want to know how many calories you would need to lose fat weight without sacrificing muscle. The simplest approach to diet recommends that your carbohydrate intake should be approximately 40 to 50 percent of your daily calories, 20 to 30 percent from fat and 20 to 30 percent from protein. In addition these calories should contain between 27 grams and 40 grams of dietary fiber a day.
Of course the U.S. Department of Agriculture (USDA) guidelines are slightly different, as are the various diet gurus. The context of consumption must be personalized to the individual. People respond differently to food choices. The truth of the matter shifts to how your fat cells react to the calories you consume. Then there are those clients who tell me it is impossible for them to lose weight because they end up eating so late. By the way it doesn’t matter what time of day you get those calories. Your body doesn’t say, “Hey it’s late, so what you’re eating is headed straight to your gut”. What matters are how many calories you expended during the day verses how many calories you took in? I totally disagree with the “don’t eat late mantra”, because we are all individuals uniquely engineered with different lifestyles. With that being said, if you’re really sedentary and don’t need much energy, nighttime may not be the best time to take in the bulk of your calories. The bottom line is to eat according to your daily activity level.
Claude Bouchard, Steven N. Blair, and William Haskell, Physical Activity and Health, 2006.
Claude Bouchard and Eric P. Hoffman, Genetic and Molecular Aspects of Sports Performance, 2011.
Claude Bouchard, Barry D. McPherson, and Albert W. Taylor, Physical Activity Sciences, 1991.
AMERICAN COUNCIL ON EXERCISE (ACE) MANUAL, edited by Mitchell Sudy1993.
The American College of Sports Medicine, www.acsm.org.
Frances Sizer and Eleanor Whitney, Nutrition Concepts and Controversies, 9th Edition.
William Evans, Ph.D. and Irwin H. Rosenberg, MD. with Jacqueline Thompson, BIOMARKERS, 1991.