How does metabolism influence weight loss?

Caroline M. Apovian, MD
Endocrinology Diabetes & Metabolism
Did you know that your metabolism changes as you age?  This process begins for most of us around age 30. Your metabolism actually ages faster than the number of candles on your birthday cake—slowing down by 5 percent each decade. By age 45, you’re burning about 200 fewer calories per day than you did when you were 25. This translates into a weight gain of up to 12 pounds per year.  In addition, the complex process of metabolism affects every function of your body, including energy level and cognitive functioning. As we age and our hormonal levels fluctuate, muscle loss further lowers your body’s metabolism, replacing your lean muscle tissue with fat, which generally settles in around your midsection, hips, and thighs.

You can reignite a stalled metabolism. Accomplish this by eating more protein, vegetables, and fruits. This ensures that your body stays full, fueled, and has the essential amino acids necessary for cell and tissue regeneration and repair. Build muscle through strength training exercises and make sure to get a full night’s rest. Studies have demonstrated that getting enough sleep is essential to optimal body function, including maintaining a healthy weight.  Follow this advice, and you’ll be on your way to burning fat, losing weight, maintaining brain function, feeling energetic, and keeping your immune system strong.
The Age-Defying Diet: Outsmart Your Metabolism to Lose Weight--Up to 20 Pounds in 21 Days!--And Turn Back the Clock

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The Age-Defying Diet: Outsmart Your Metabolism to Lose Weight--Up to 20 Pounds in 21 Days!--And Turn Back the Clock

Age slowing down your metabolism? Not anymore!Internationally renowned weight-loss expert and New York Times bestselling author Dr. Caroline Apovian has developed an innovative program that outsmarts the body's aging processes and reverses the metabolic clock. By combining the metabolism-boosting effects of her unique take on intermittent fasting-an innovative approach that will leave readers feeling full, not hungry-with targeted strength training, readers can lose up to 20 pounds in 21 days while they reshape their bodies and take back their youth.Reboot - one week to jumpstart weight-loss with Super Smoothies, Super Soups, and delicious whole food meals that rekindle the metabolic fire.Recharge - two weeks to keep metabolism running in high gear, burning more fat and building more muscle. Revitalize - a powerful blueprint that keeps the metabolism young and keeps age-defiers slim for life!
Metabolism is the rate at which our body utilizes our nutrition. While there are many factors that influence our metabolism (hormone levels, enzyme secretion, chronic disease conditions, medications, stress, activity level and sleep patterns). The rate of metabolism directly effects caloric need and impacts weight loss or weight gain.

Healthy, physically active individuals generally have an appropriate BMI, body mass index, and are within their ideal body weight range. This means that the calories they are ingesting are being utilized for energy and to maintain their normal body weight in a balance ratio. When we become less active or ingest more calories than we are using for energy and activity, those additional, unused calories are stored as fat in our adipose tissue.

Body mass index can be an excellent indicator of the rate and efficiency of your metabolism. The Center for Disease Control and Prevention has an excellent on-line calculator that can assist you in calculating your BMI, which will provide feedback on the ratio of your calorie intake to your calorie utilization.

If our metabolism slows down because of hormonal changes, such as menopause, we can see how important the overall health of our body chemistry is to our metabolism and weight loss. Women can struggle with weigh loss after menopause because the loss of the female hormones decreases the rate of metabolism, as estrogen is an intracellular metabolic hormone as well as a reproductive hormone. Pregnancy increases our metabolism are we are processing additional nutrition and energy to accommodate the nutritional needs of the growing fetus.

Physical activity increases the utilization of glucose and fat, and generally increases our metabolic rate. Stress and sleeping difficulties can decrease metabolism due to increase levels of cortisol, which slows down the rate of metabolism to conserve calories for the increased nutritional needs that occur during stress.

This CDC calculator is easy to use and may help you start on a program of monitoring your BMI for weight loss and health improvement.
Changing Behavior: Immediately Transform Your Relationships with Easy-to-Learn, Proven Communication Skills

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Changing Behavior: Immediately Transform Your Relationships with Easy-to-Learn, Proven Communication Skills

FREE CHAPTER DOWNLOAD at AWARD WINNER 2013 International Book Awards --- WINNER 2012 Indie Book Awards --- AWARD WINNER 2012 USA Best Book Awards ---AWARDED - 5 STARS...
Paula Greer
Midwifery Nursing
Metabolism is a very important factor in your weight loss efforts. If you have been skipping meals, have vitamin deficiencies, are inactive and somewhat of a couch potato chances are your metabolism has slowed down. Your resting metabolism is the number of calories your body burns at rest. Muscle burns more calories than fat so when you are overweight your resting metabolism is slower than someone who has more muscle mass. To lose fat and not muscle which is the goal in healthy weight loss you need to have a efficient metabolism. This can be achieved by eating foods that will boost your metabolism and address any vitamin deficiencies, eating frequent small meals and exercising on a regular basis.
Neal Spruce
Neal Spruce on behalf of dotFIT
In the context of weight loss, metabolism is considered how fast and how many calories you burn daily, therefore theoretically, metabolism should dictate how quickly or easy it would be for someone to lose, gain or control their weight. Unfortunately, fast and slow resting metabolisms are more of a myth than reality. Although two people of the same weight, height and body composition may burn calories at a slightly different rate, the difference is so small it’s virtually insignificant in the big picture. And no matter who you are, the heavier the body, the more calories it burns in all activities. Contrary to what most people believe, we do have control over our metabolism and how fast we lose weight. As an example, simply standing up instead of sitting burns more calories, so minimizing time spent sitting will boost your overall metabolism. If you start walking or doing any activity on a regular basis, your metabolism will increase significantly.

There are 3-parts to our metabolism, one of which we have full control:
  • Resting Metabolic Rate (RMR): The amount of calories burned while in a resting/quiet state. RMR for an average person is the largest part of total metabolism accounting for 65-75% of calories burned daily. We have little control over RMR unless we add a significant amount of muscle or weight leading to an increase of calories burned (3-6cals/day/pound depending on muscle to fat content).
  • Thermic Effect of Food (TEF): This is the energy used by the body to digest and absorb food. The energy used for TEF accounts for ~ 10% of calories burned. We have little control over TEF.
  • Physical activity: The amount of energy the body burns during daily activities such as exercise, recreation, work, housework, etc. Daily physical activities can account for 10-50% of calories burned each day depending on the individual’s activity. Therefore we have complete control over this aspect of metabolism. A sedentary person will require fewer calories to maintain weight than a more active counterpart. So the moral of the story is never sit if you can perform the same activity standing or pacing, whether it’s phone work, reading, watching your kids, meetings or even working at your desk (many people now use standup desks).
So you see, you have complete control over your daily metabolism -- so go ahead and move it and lose it.
Kirsi Bhasin
Nutrition & Dietetics

Your metabolism plays a key role in losing weight.  Your metabolism is what helps your body burn fat, stay energized and be healthy.  Metabolism really means the rate at which you burn your calories and, ultimately, how quickly you gain weight or how easily you lose it.

Everyone burns calories at a different rate. Age, gender and lean body mass i.e. muscle all influence your metabolism.  Your metabolism naturally slows about 5% per decade after the age of 40. Men tend to burn more calories at rest than women. Also the more muscle (lean body mass) you have, the higher your metabolic rate tends to be.

Your metabolism slows down if your body does not get the nutrients it needs on a daily basis to work efficiently.   For example, when you exercise, your body uses magnesium to help energy molecules move to where they are needed. If you are low on magnesium you’ll most likely start feeling tired more quickly.  Iron is also an important nutrient that supports your metabolism. In fact 20% of us are iron deficient. Check your levels and make sure you are getting enough.  A great source of iron is lentils and a great source of magnesium is white beans.

Chris Powell

Your metabolism determines how many calories you burn, whether you're exercising or sitting on the sofa. In this video, fitness and weight loss expert Chris Powell explains how changing your metabolism can help you peel off the pounds.

Samantha Heller, RD
Nutrition & Dietetics

You've heard the term metabolism, but do you really know what it means? In this video, registered dietician and Dr. Oz Show guest Samantha Heller shares details that can make the difference when you're trying to lose weight.

Metabolism is the number of calories the body burns. The higher your metabolism, the more calories you burn. You need to burn more calories than you use to lose weight.

Your metabolism is determined by your resting metabolic rate, how much physical activity you get, and the calories used to digest and absorb food. Resting metabolism encompasses the calories used to keep all systems going day in and day out: It is the calories burned by the brain, heart, kidneys, and all organs and cells in the body. Calories burned in physical activity are the most variable part of metabolism and also the component over which you have the most control.

Over the long term, muscle tissue burns more calories than fat tissue, so a person with a lower body fat percentage will have a higher metabolism and burn more calories at rest than a person of the same weight with a higher body fat percentage.

Weight Watchers offers a comprehensive approach to weight loss that can help you reach your goals.
Dr. Mark Hyman, MD
Family Medicine
Watch as functional Medicine Specialist and family physician Dr. Mark Hyman discusses how an individual's metabolism influences weight loss.

Metabolism influences weight loss because it is the amount of calories your body uses to keep itself alive. To lose weight, you must burn more calories than you consume.

A person with a high metabolism uses more calories to perform all of it's required functions than a person with a lower metabolism.

With respect to weight loss, a higher metabolism will burn more calories faster.

And that's exactly what you need, calories being burned.

So don't starve your body at all.

Make sure to keep giving it high quality foods all day long.

Remember...Smaller portions more frequently.

What you want is for your body to use the calories you give it from your food as energy and then tap into your fat reserves and start using that as energy.

By doing this consistantly, you will raise your metabolism, which means raising the amount of calories your body uses as energy to keep itself going.

When your body burns more calories from a higher metabolism, it is tapping into stored body fat more frequently to use as energy.

This is one thing that directly influences how much weight you will lose.


In simple terms, metabolism is the rate at which your body naturally burns the calories you take in. Metabolism is influenced by age, gender and body composition, or lean to fat ratio. The lower the body fat and the higher the lean muscle tissue, the higher metabolism tends to be. A combination of a healthy diet, cardio-vascular exercise and weight training can help you to change your body composition and have a positive effect on your metabolism.
Kat Barefield, MS, RD
Nutrition & Dietetics
Your metabolism essentially determines the calories you burn. The part of your metabolism that you cannot control is your resting metabolism, which is the calories you burn to keep you alive at rest. The part you can control is your activity level, or the amount you move throughout the day. The more active you are, the higher your metabolism and your daily calorie burn. Therefore, regular physical activity boosts your metabolism and makes it easier to lose weight and keep it off. You can also control your metabolism by maintaining or increasing your muscle mass as you age with regular resistance training. This prevents the loss of muscle, which causes our metabolism to slowly drop.
It's important to note that physical activity includes exercise as well as daily activities such as housework, gardening, pacing and playing with kids. To help boost weight loss, stand and move at every opportunity. Every calorie burned counts. In fact, I’m typing this as I walk on my treadmill desk in my office. Instead of burning only 70 calories per hour from sitting, I'm burning over 200 calories walking at 2 mph. I'm able to maintain a healthy body weight, I'm more productive, creative and I don't get that afternoon energy dip that many people experience. The bottom line - focus on what you can control, and that's the amount you move during the day....
Dominique Adair

The word metabolism is used these days in so many ways these days.  People complain of a “slow metabolism” or they say something they did “slowed down their metabolism.”  Scientists use the term basal metabolic rate (BMR) – which sounds really complicated but it’s essentially the energy you need to blink and swallow.  Our bodies actually need energy just to be at rest.  In other words, your lungs need energy to be lungs; your kidneys need energy to be kidneys; even your bones need energy to be bones.  If you add all these live tissues up you get metabolism, or BMR. An easy way to picture metabolism is the energy you need to blink and swallow.  After that, as soon as you swing your legs out of bed, or walk up a flight of stairs, you need MORE energy than your BMR.

We keep talking about “energy” without mentioning a way to measure it.  One useful way to measure energy is in calories – whether we’re measuring the energy in foods or the energy our bodies expend, we can measure both in calories.  There are sophisticated ways of measuring metabolism that we use in physiology labs, but most of us will never know how many calories we use at rest, and it probably doesn’t matter.

Now let’s put this all together.  Our “metabolism” is the fairly constant number of calories our bodies burn just existing at rest.  But a far more interesting number is the calories our bodies burn during activity.  Yes, changing body composition (adding muscle/losing fat) can change your metabolism a little, but a far greater impact on weight loss will be how many calories you expend (burn) during activity versus how many you eat during the day.

Rather than focusing on metabolism (which scientists believe is a pretty resistant biological property – like it or not!), for weight achievement we should focus on eating slightly less and exercising a little more.  Then we impact ENERGY BALANCE which is a far more potent way to manage weight than trying to change metabolism.

Bob Greene
Bob Greene on behalf of The Best Life

First off, it's important to understand what metabolism is. It's the rate at which your body burns calories. The rate varies depending on what you're doing. For example, when you sleep, your metabolism burns calories at a slow rate, because you're at rest. When you exercise, however, your metabolism burns calories at a high rate because you're working hard - your heart is pumping, your muscles are contracting, and your breathing is rapid. How much your metabolism increases when you work out is directly related to your exercise's intensity. The longer and harder you work out, the higher your metabolism, and thus, the more calories you burn.

The key to weight loss then is to elevate your metabolic rate as much as possible. That's why you should perform regular intense aerobic activity at least three days a week, and some kind of activity every day, even if it's simply walking around the neighborhood. When you exercise regularly, you gradually increase your metabolism so it stays elevated for longer stretches of time. The result: More fat burned and more weight dropped.

There's no way to directly measure how your metabolic rate changes from workout to workout, but a good gauge is how you sweat. As you burn calories at a higher rate, you'll begin to perspire sooner into your workout and more than usual. It's a simple formula to follow: Keep your metabolic rate up and lose weight; let it drop and body fat increases.


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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.