Frequently Asked Questions about Metabolism (Plus How You Can Boost it).
By: Kia Khadem MSc (c), CSEP-CEP
Over the last past few weeks, I asked my readers and Facebook friends what they wanted to know more about. The most common questions I got were related to metabolism. So, let’s understand metabolism better and how you can boost it.
Q: WHAT IS METABOLISM?
Energy is used by the body for growth and repair, such as building and repairing muscle after exercise. Energy is also used to breakdown and transport substances throughout the body. All the chemical reactions in the body are collectively called metabolism. How much energy the body uses for these reactions is the metabolic rate. Your body weight can be maintained when energy in equals energy out. However, a lot of things influence how you maintain energy balance. To better understand metabolism and total metabolic rate, we need to understand what influences it. Resting Metabolic Rate (RMR)
- This is the amount of energy your body needs to function at rest.
- This makes up 60% to 75% of the total energy you spend each day.
- Age, sex, body size, body weight, and body composition influence this.
Thermic Effect of a Meal (TEM) *also referred to as thermic effect of eating, and thermic effect of food.
- This is the energy cost of digesting and absorbing food.
- This makes up about 10% of your daily energy spent.
- A higher protein diet has a higher thermic effect.
Thermic Effect of Exercise (TEA)
- This is all your sports, running, weight lifting, and Zumba.
- Makes up 15% to 30% of daily energy expenditure.
Non-Exercise Activity Thermogenesis (NEAT)
- This is the energy you spend fidgeting, twirling your hair, tapping your foot or shaking your leg. Things of that nature.
- This is subconscious and is not something you really can control voluntarily.
- Influenced by genetics.
Q: DO WOMEN HAVE (S)LOWER METABOLISMS?
Yes. Muscle has a higher metabolic activity compared to fat. And RMR is related to muscle mass or lean body mass (LBM). LBM is everything in your body besides fat such as organs, muscles, bones, skin, etcetera. Because women usually have less lean body mass and a greater percentage of body fat than men, women usually have a lower RMR than men of a similar weight.
Q: WHY IS IT HARDER FOR ME TO LOSE WEIGHT, AS I GET OLDER?
Your RMR goes down about 2.5% per decade after age 40 generally because of a decrease in lean body mass. This is why it’s so important to continually strength train to maintain this.
Q: DOES DIETING LOWER MY METABOLISM?
Yes, here's why. Dieting means eating less which directly affects your TEM. Because when you eat less food less energy is used to digest and absorb it. As you diet goes start to lose weight your RMR also decreases. Because, as mentioned above, RMR is related to body size and body weight. Dieting also usually decreases your energy levels. This makes your body want to conserve energy and so you tend to move around less. Thus, the amount of NEAT goes down.
Q: I KNOW PEOPLE WHO CAN EAT ANYTHING BUT NEVER SEEM TO GAIN ANY WEIGHT.
While on the surface it may seem like that, the people you’re thinking of, are still maintaining their energy balance in one of two ways.
They’re not eating as much as you think they are. For example, you might see them have a slice of pizza and hamburger for lunch at work, but their other meals are smaller.
They have a higher level of NEAT. Research shows this to be a highly genetic factor and one of the biggest factors related to weight control. So much so, that some people increase NEAT when they overeat, which means they don’t gain weight as easily.
Body weight comes down to energy in versus energy out. When you’re in an energy balance your weight stays the same.
Energy Intake - Energy Spent = RMR + TEM + Exercise + NEAT
If you’re a genetically gifted person like myself who constantly fidgets and feels full quite quickly, you will have a much easier time controlling your weight.
Q: HOW CAN I INCREASE MY METABOLISM IF I HAVE LOW NEAT?
Choose different parents. If that's not possible, you can do the following: 1. Exercise is the obvious choice. You can increase the intensity and/or duration of your workout. This will increase your amount of TEA. 2. Increase your protein intake by eating close to a gram of protein per pound of body weight. Studies show this can increase metabolism of up to 100 calories a day. This happens when you replace carbohydrates or fats with protein, so you need to keep your total caloric intake the same. 3. Increase NEAT. Move more frequently throughout the day. Get a FitBit or step tracker and make more trips to the water cooler. You'll stay hydrated and you'll never miss out on any office gossip. Plus, walking at only 1 mile per hour, will doubleyour energy expenditure over sitting.
Q: I HAVE A HARD TIME LOSING WEIGHT. SHOULD I BLAME MY GENETICS OR MY ENVIRONMENT?
Genetics affect how your body absorbs and uses nutrients, your levels hunger and appetite when you eat, how much exercise you can handle, and even how much your enjoy exercise. Some people feel satiated (feel full) faster than others. Some freaks of nature can exercises at very high levels for a longer duration per session and on consecutive days. Others can handle less work and may need more days to recover between sessions.
As mentioned above, genetics also determine NEAT and how many calories you burn subconsciously. According to nutrition expert Lyle McDonald, “It turns out that NEAT can account for 200-900 calories per day of caloric expenditure and there is a massive variance between people. This is especially true during overfeeding; some people ramp up NEAT to super high levels and stay lean, others don’t and get fat easily.” However, the role of the environment might be more important. The environment includes your home, work, neighborhood, and even your social circle. And the environment can affect behavior. Alan Aragon, MS, and author of The Lean Muscle Diet, believes that while genetics play a role, it's an individual's behavior that has a larger effect. "Genetics predispose, but behavior dictates the outcome. Someone might have 'fat' genetics, but it's his/her behavior that will ultimately determine whether or not those genes are allowed to express themselves." Whether you're a fitness professional working with clients or you're someone trying to lose weight, I think we can all agree that diet and training are the cornerstones for a successful outcome. But as Alan says, most programs are missing a vital piece of the puzzle - priming the eating environment for dietary success. "You can educate & counsel all you want, but if the person goes home to an environment (including social factors, not just how the food is stocked or displayed) that antagonize the goal, then that could compromise success."
I hope this information helps you understand the topic of metabolism better and what you can do to boost it. If you have any questions, feel free to leave them below or send me a message on any social media platform :)
McDonald, L. (2009, February 5). Metabolic Rate Overview. Retrieved February 28, 2016, from http://www.bodyrecomposition.com/fat-loss/metabolic-rate-overview.html/
Johnston, C. S., Day, C. S., & Swan, P. D. (2002). Postprandial thermogenesis is increased 100% on a high-protein, low-fat diet versus a high-carbohydrate, low-fat diet in healthy, young women. Journal of the American College of Nutrition, 21(1), 55-61.
Wilmore, J. H., & Costill, D. L. (2006). Physiology of sport and exercise. Champaign, IL: Human Kinetics.