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Many people use the word metabolism, but few know what it actually means. Indeed, if you asked a room filled with a hundred doctors and nutritionists, “What’s the definition of metabolism?” you’d likely hear a hundred different answers to the topic metabolism definition. It’s no surprise, then, that the rest of us would be confused about this topic. So in the spirit of furthering science and making nutrition and health a lot more interesting, let’s take a look at the old definition of metabolism, and come up with a newer one that’s more crispy and fresh.

Here’s the basic, undisputed classic textbook definition of metabolism:

Metabolism is the sum total of all the chemical reactions in the body.

Are you surprised it’s that simple? Of course, we can talk about the metabolism of such specific tissues as the liver and thyroid. We can talk about the metabolism of specific substances such as cholesterol. We can also talk about the metabolism of different body systems, such as digestive metabolism. People who say “I want to speed up my metabolism” are actually referring to calorie-burning metabolism, also known as thermic efficiency.

With this understanding, if we wanted to “increase metabolism”, we’d make it our business to kick-start our body’s chemical efficiency with exercise, drugs, the latest supplement, or the magic combination of foods. These approaches have certainly proven useful, but they are no longer adequate in describing metabolic reality.

That’s because metabolism doesn’t occur in the body alone.

It operates equally and simultaneously in body, mind, and emotion. Astounding research in the mind-body sciences has exquisitely highlighted the connection between what we think and feel, and the chemistry of the body. Science has revealed the profound effects of the chemistries of stress, relaxation, pleasure, depression, and the effects that even prayer, pets, and other people have on our metabolic lives. Simply put, mind influences chemistry.

Indeed, everything that happens in our world from birth until death is part and parcel of metabolism. All sensory input that impacts the human nervous system undergoes some form of digestion, assimilation, and elimination.  In this very moment, we’re metabolizing elements of our last meal, words on this page, and important details of pivotal events that happened earlier this week or even previously in our lives. We metabolize our dreams, fears, and fantasies, our ups and downs, our jealousies and joys, the beauty that surrounds us, the betrayals we’ve suffered, and our fortunes and misfortunes – this in addition to all the frozen yogurt, chicken sandwiches, and sushi we eat. No wonder we take so many digestive aids.

So taking all these elements into consideration, our new, more updated, and more scientifically correct definition of metabolism would look something like this:

Metabolism is the sum total of all the chemical reactions in the body, plus the sum total of all our thoughts, feelings, beliefs, and experiences.

Not only is this definition of metabolism more biochemically accurate and complete, you might also recognize it as intuitively correct. If you do, then you are in sync with such disciplines as Ayurveda and Chinese Medicine, which for thousands of years have acknowledged the inseparable nature of mind, body and cosmos. Chances are you’ve had many moments in which your metabolism was transformed by something other than food, drugs, or exercise. Can you recall a time when you were sitting at home feeling low energy and sorry for yourself, a time when if someone asked you “How’s your metabolism?” you would have answered that it was sluggish and stuck? Then quite suddenly the phone rings and it’s a love interest calling, or it’s someone reaching out to you with good news about money. Your mood instantly skyrockets. You feel alive and optimistic. And in that moment, if we asked again, “How’s your metabolism?” you’d say it was humming.

So what happened? You had an enormous energy rush yet you didn’t drink any coffee or take any drugs. It was a shift in your emotional world that ignited the chemistry in your body. And that’s how quickly metabolism can change.

Many people have come to believe that somehow they’ve been shortchanged on their metabolic allotment. We think we don’t have enough chemical force to lose weight, have enough energy, or be immune-strong because somehow, our metabolic machinery has broken down. All we need to do it fix it with a vitamin, a drug, a diet, or an exercise program. If only we could find the right expert with the right answer, it would all work out.

The truth is, we are born metabolically powerful.

If you’ve made it this far, the miraculous body you inhabit has done a worthy job. The forces of the universe launch us with a life-sustaining thrust that enables us to gather along our journey all that we need to continue to soar. But when we stay trapped in fight-or-flight survival physiology because of chronic, low-level stress, because of speed, because of a lack of breathing, awareness, and pleasure, and because of discordant rhythms and unkind thoughts towards self and others, we lose power big time. Furthermore, we lose power when we surrender our dignity and our inner authority to a job, to money, to the “experts,” to hurtful emotions, and to a life without love – to name just a few.

The point is, we have more ways to impact metabolism than we could have imagined. Yes, we need to eat in a good way and take care of our body chemistry with the right supplements and strategies. But we also need to remember that everything that happens in our inner world has an impact – and often profoundly so – on our metabolism.

Claim your personal power more and more, be the person you’re meant to be in this life, and you claim a wealth of metabolic strength. It’s as simple as that. And it’s as profound as that. Personal power and metabolic power are one and the same. Improve one, and you improve the other.

But don’t just take my word for it. Experiment for yourself. Notice how your health is infused with an extra helping of vitality when you allow the real you to emerge.

And of course, I’d love to hear your stories and insights around how your metabolic power has increased when your personal power was more fully accessed. How have you seen this to be true?

My warmest regards,
Marc David
Founder of the Institute for the Psychology of Eating
© Institute For The Psychology of Eating, All Rights Reserved, 2014


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  • Annie

    Oh Marc, I wish I could sprinkle fairy dust on the whole of mankind, so everyone would just naturally know, what you are so diligently teaching people. I know things are changing, but I would just love, that you only had to teach the minority and not the majority, and people would understand, it’s so how they live and think, that is just as important as what they eat. So simple, but so foreign to most.
    I love your newsletters, and quote you as often as I can.
    Thank you so much!

    • Hi Annie,

      Thank you so much for the kind words and encouragement, and for your enthusiasm as well. The important thing is that we help who we can whenever we can, and the wonderful thing is, this is how the message is spreading – this is how the minority turns into the majority! More and more people are awakening to this idea of the intuitive side of themselves.


      Marc David

  • Cheryl

    Dear Marc,

    How true your words are. For years I struggled with toxicity….that yucky feeling in my body that led me to do detox after detox, & use product after product in an attempt to clear the toxins from my system, that I knew were making me feel lethargic & run down.

    It wasn’t until I met an amazing, intuitive man that pointed out the source of my toxicity was the anger I was holding against my father (we hadn’t spoken in 2 years) that was affecting my liver metabolism.

    With this realisation, my father & I were talking again within the week, & have been best buddy’s ever since. My body felt detoxed & alive within days, without any detox aids & I have never looked back.

    The state of the mind & spirit is certainly powerful where our health is concerned & it is our choice & responsibility as to the extent we have health & vitality show up in our lives.

    Thank you for your contribution to the health of the world.



    • Hi, Cheryl —

      Good for you! It’s truly amazing how much healing happens inside when we take responsibility for the state of our mind and heart, and furthermore, how quickly the body responds when we take action in this way! What a great testimonial to the power of letting go. Thank you so much for sharing your story.

      Warm regards,

      Marc David

  • Hi Marc!

    Could agree with you more! Great blog.

    Very happy to read it. You are definitely on track with this.

    Very best wishes,


    • Hi Katie!

      Thank you for your support!


      Marc David

  • Karina Francois

    This is so very true 🙂 Thank You For sharing .

    • Lindsay Young

      Hi Karina,

      Lindsay at IPE here. We’re always happy to share and we’re so glad you liked it!

  • Diana Walley

    Hi Marc,
    I love your site! I’m very interested in reading more about this topic. Can you recommend books or articles in the mind-body sciences regarding metabolism and the mind?

  • Your Food Psychology training changed my whole life. And i love all your articles. This one was particularly awesome in that, I have always believed this to be true and you just confirmed it. We are constantly evolving and changing inside and out and we must make the most of every oppurutnity to respond the body and the spirits direct needs. Thank you for your articles and your knowledge and wisdom. Keep it coming.

    • Hi Jodelle –

      I’m so glad that my work has inspired you.
      Thank you so much for your kind words and your willingness to live responsibly, that is, responding to the ever-evolving you!


      Marc David

  • This is wonderful and I have shared it on my holistic nutrition page. thank you.

    • Lindsay Young

      Hi Lisa,

      Lindsay here at IPE. Thanks so much for the link-love.

  • Nancy Lundy

    Marc, thank you so much for all your knowledge…I’m new here and to be honest, I just can’t get enough. I’m reading and reading and then rereading. I have fought with food and my weight my entire life…blamed my metabolism for years of frustration…everything you wrote here is so damn true…my fight has actually been with my troubled past, negative thoughts, blame and SO much more. I’ve tried so many times to lose weight, struggled with frustration and now I’ve started blaming my age (51) for my failures. I will try each day or even each moment to move away from this and start to release my sabotaging self talk. Firstly, I will forgive myself for old ways so I can find the kindness to move to new ways. Thank you so much.

    • Hi Nancy,

      Thank you for reaching out and sharing some of your personal story. I’m thrilled to hear this information is ringing true. You’ve experienced that brilliant moment of clarity: no more need for blame, and no need for sabotaging mental chatter.

      Isn’t it inspiring to know there’s something more intimate at work than just facts and figures and fads? Now comes the most worth-while and sometimes difficult next step: staying present and aware and remaining willing to listen out for what you really desire.

      Excellent – so happy for you!

      Warm Regards,

      Marc David

  • Thank you for this great post! I can totally relate to the feeling that when I’m excited or joyful I feel like I’m losing weight (metabolism boost!) and when I’m down and sad I feel like my metabolism is coming to a halt. Very interesting!

    • Hi Rachael —

      You got it!
      It’s amazing how the body turns on and turns off,
      it’s a great tool if we know how to listen.


  • Katie S

    First of all THANK YOU for the work that you are contributing to the world right now. I am beginning to put the pieces together that my weight has been an expression of a combination of resentments and a fear of living authentically. The more that I empower myself to believe in myself and claim my natural gifts, I feel that inner “ping” that you describe without the aid of coffee. I feel powerful and lighter. I am trusting that my body will follow my minds lead. If I love myself, then I love my life then hopefully I will love food in the same way.
    Thanks again!!

    • Hi Katie,
      This is a beautiful journey of discovery you’ve embarked on… What a powerful moment to look in the mirror and see that fear of living authentically looking back at you. I’m so glad to hear you’re already noticing small and fruitful changes. Thank you for sharing your story with us…

      And best wishes to you,
      Marc David

  • Simona

    Perfect! – as always. I tend to have metabolic struggles when having loose boundaries, undecision, cauth up in unhealthy relationships or when sexually suppressed.
    It’s a call for standing up for myself!

    Thanks, Marc, you’re a rolling stone for me!

    • Hi Simona,
      These are great insights you’re noticing about yourself and where you get bound up – thanks so much for sharing…


  • Jossygoody

    this is a very courageous write-up dear marc, more grease to your elbows.

  • Kashif Ansari

    yes you sure hit the nail on the head. western civilization is one-sided so the biochemical model is all it can see through its blinkered vision. the east has a lot of wisdom in the form of the electromagnetic model which is light years ahead of the western simplistic model. not only your emotions and thoughts but your very imagination and spiritual state influence your metabolism. a person who keeps tabs on his behavior and is lissome not to mention metaphysically intense will lose weight. weight loss has so much to do with a strong personality and it is all about being a hero in your own mind. people with low self esteem end up piling on the pounds. don’t see what goes into your mouth but what comes out of it in the form of words. they have to be measured and clipped if you want to lose weight.

    • Hi Kashif,

      Thanks for sharing your thoughts, well said – and I’m glad you connected with the article.


  • Julie

    Thank you so much for this. Your post are a constant reminder to me to center myself and remember what is truly important to me.

  • Thanks so much for your comment, Julie-Anna! Remembering to center is a lifelong practice — we’re so glad to be part of your journey.

  • Nellie Baktashi

    I can’t believe I just stumbled upon this amazing article of yours. I have been following psychology of eating a lot more lately and as a Nutritionist I appreciate your tips. It has not only helped me in my own life, but it has also given me a chance to explore this realm of mind body science with a more open mind. Thank you and I hope to meet you and or interview you for my blog one day!

    • Wow! Thanks for the praise, Nellie Baktashi!! We are thrilled to have you in our community 🙂 Warmly, Marc

  • Hi Ibrahim, thank you for sharing about your son with us.
    We send our heartfelt wishes.
    Please reach out to us at
    Warmly, IPE Staff

  • Hi Pranshu, thank you for your comment! We are so glad the article really resonated with you. You pose an interesting question that could have many possible answers. In this case there can be a big difference between desiring power over others versus seeking empowerment, or personal power, for one’s personal growth and development. When it comes to personal power or empowerment, it has little to do with your status in life, financially, or in a job. Someone in a higher up position does not necessarily realize his or her personal power more than someone in a lower position. That is something that comes from within with a commitment to self-awareness and personal development. I hope this helps answer a little bit. Of course, it’s a complex question that could have a very complex answer.

    We so appreciate you taking the time to read the article and to share your thoughts.

    Warm regards!
    IPE Team

  • Jo-e Sutton

    Fabulous post on the holistic view of metabolism Marc. Thank you for this. I’m editing a book that my agent awaits on how to navigate the modern day food supply from a holistic perspective, including over a hundred recipes to back up whole food eating. I’m on a chapter about food metabolism and came to this posting, only to find the most beautiful definition of metbollsm, far more impressive than Webster’s could conjur. Thank you for what you have had to do, to express such beauty. Jo-e at

    • Thanks for sharing Jo-e! It sounds like you are doing great work. We appreciate your support as well. 🙂

      The IPE Team

      • Jo-e Sutton

        Thank you for your reply. I would like to use your definition of metabolism in my book citing you as a resource. Is there anything else you need, to feel comfortable being cited?
        thank you so much.

About The Author
Marc David

Marc David is the Founder of the Institute for the Psychology of Eating, a leading visionary, teacher and consultant in Nutritional Psychology, and the author of the classic and best-selling works Nourishing Wisdom and The Slow Down Diet. His work has been featured on CNN, NBC and numerous media outlets. His books have been translated into over 10 languages, and his approach appeals to a wide audience of eaters who are looking for fresh, inspiring and innovative messages about food, body and soul. He lectures internationally, and has held senior consulting positions at Canyon Ranch Resorts, the Kripalu Center for Yoga and Health, the Johnson & Johnson Corporation, and the Disney Company. Marc is also the co-founder of the Institute for Conscious Sexuality and Relationship.