How to Upregulate Metabolism

How to Upregulate Metabolism
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A biochemical clue as to why vegetarians tend to be significantly slimmer than the rest of the population.


While soy and turmeric can suppress human fat cells, not all vegetarians eat curried tofu. So, this still doesn’t explain why vegetarians are so much slimmer, on average, than meat-eaters. Well, we’re getting closer to an answer.

The reason I chose to major in biophysics, rather than biochemistry, is because of diagrams like this. This is the simplified version of human metabolism. The real deal is controlled by about 25,000 genes.

Let me focus in on one in particular. This appears to be the enzyme that does much of the heavy lifting: carnitine palmitoyltransferase—CPT here—shovels the fat that we eat into the furnaces in our cells.

The more active it is, the more fat we burn. That’s where a vegetarian diet seems to come in. Here’s our man CPT, significantly upregulated in vegetarians, boosted by about 60%. We’re not sure why, but that may help explain why those eating vegetarian are so slim.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by veganmontreal.

Please consider volunteering to help out on the site.

While soy and turmeric can suppress human fat cells, not all vegetarians eat curried tofu. So, this still doesn’t explain why vegetarians are so much slimmer, on average, than meat-eaters. Well, we’re getting closer to an answer.

The reason I chose to major in biophysics, rather than biochemistry, is because of diagrams like this. This is the simplified version of human metabolism. The real deal is controlled by about 25,000 genes.

Let me focus in on one in particular. This appears to be the enzyme that does much of the heavy lifting: carnitine palmitoyltransferase—CPT here—shovels the fat that we eat into the furnaces in our cells.

The more active it is, the more fat we burn. That’s where a vegetarian diet seems to come in. Here’s our man CPT, significantly upregulated in vegetarians, boosted by about 60%. We’re not sure why, but that may help explain why those eating vegetarian are so slim.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by veganmontreal.

Please consider volunteering to help out on the site.

Doctor's Note

Check out these videos on preventing obesity through plant-based diets:

And check out my other videos on vegetarians. And go here for all of my videos on weight.

For some context, please check out my associated blog posts: Boosting Gut Flora Without Probiotics and Avoid Carnitine and Lethicin Supplements.

If you haven’t yet, you can subscribe to my videos for free by clicking here.

45 responses to “How to Upregulate Metabolism

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  1. Hi ARC,
    Good fats must be considered carefully since they can be processed to become bad fats as well (i.e. converting them to transfats). Additinoally, there are no “free” oils in nature: oils that are extracted from their natural settings of fiber, vitamins, minerals, etc.,can jeopardize one’s health. Consumming too much oil (good or bad) can lead to obesity, diabetes type II, cancer, immune system depression. Great studies to view:
    Balance it with this

    1. Hi Xgabrielzx, I’m curious to learn which portion of the article cited in the video you noted as describing the vegetarian diet as unhealthy. I may have missed it, since my impression was a bit different: I noted of the authors’ comments that vegetarian diets are characterized by increased fat metabolism and reduced collagen synthesis, and that these features comprise health benefits that contribute to a slower rate of aging. Thank you in advance for elaborating, and when you have a moment, check out another mechanism that enables plant-based diets to extend our lifespan, since it seems that bypassing meat and animal products builds health from several angles.

  2. To what degree does heat from steaming and baking in oven destroy vitamins and minerals? For example, is there any nutrition left in a baked potato done in the oven for an hour at 350 degrees Fahrenheit?

  3. I was vegetarian for over a year and vegan for 4 days of that same year. However, I was tested a couple of months ago and discovered I was severely anemic. My protein intake wasn’t that great because I do not care for beans. I subsisted mostly on grains, vegetables, fruits, and nuts. I’m back to eating meat, but I am not happy about it. How can go back to being a vegetarian and stay healthy?

    1. You can get enough protein from eating whole grains, that is not an issue. As long as you are getting enough calories, your getting enough protein. Were you b12 anemic or iron anemic? If Iron anemic, consuming lots of whole grains, as well as cruciferous greens will provides plenty of iron. When consumed with vitamin c, onion, or garlic, we will absorb more iron.

      Was your diet based on whole plant foods, or did you consume processed foods? (white flour, mock meats, oils)

      1. I am iron anemic. My diet was mostly plant based. I would buy the mock meats in the Whole Food prepared foods section. I did not consume anything with white flour or frozen foods (especially from “traditional” grocery stores) The only oil I use is olive oil sparingly.

      2. There is another nutrient which, if insufficient, causes a form of pernicious anemia – not only B12 but folic acid, preferably in the form of Folate. Folate is less liable to overdose and result in a zinc deficiency.

        Normally there are many sources of folate in food, including for vegans, but certain medications, some unavoidable, cause deficiencies. Depakote/depakane/valproate causes shortages in l-carnatine, folate, vitamin E and sometimes selenium, and the low folate causes anemia – specifically (in me) low hematocrit or hemoglobin levels, rarely both.

        Under these circumstances, supplementation of Folate and is likely needed to add to careful eating, depending on one’s dose (mine is high.) (Selenium may not be needed, and can be dangerous.)

        When using l-carnatine supplements, I’m not only careful of brand and purity, but I also take it on an empty stomach, which some bottles do not suggest. It’s a 4-to-1 difference, so a serious saving. It can’t be taken within 4 hours of medical thyroid medication; I’m not sure about nutritional supplements.

    2. You have to be carefull so that you get enough iron from spinach, pumpkin seeds, beet. Tea and coffee usually inhibit the absorbtion of iron so dont drink eighter for 2 hours after you had an iron containing vegetable. For a better absorbtion be sure ingest some vitamin C containg fruits/ vegetables shortly after a such meal. I m vegetarian and i can still donate blood every few months.

    3. Were you taking B12 Supplements? You don’t say, but I just made myself quite sick by not taking them. I didn’t think about it because I never made a decision to become vegan. I just became one over several years through separate an unrelated decisions so I didn’t put it all together and plan like a vegan. I was B12 deficient, anemic, and hypothyroid. If you do not use iodized salt, eat seaweed daily, or eat fish, make sure you take an iodine supplement. An old video of Dr. Greger’s on YouTube “called 40 year old vegan dies of heart attack” was very enlightening to me and caused me to get to a doctor have everything checked. Now I take ADD meds (some cognitive difficulty from very low B12 level), thyroid meds, as well as B12, D3, DHA Omega 3, and Iodine (I won’t go near seaweed or fish and I don’t like iodized salt). Hopefully, I will be able to get off the meds when I get back in line, but anyway, go watch his video. It is old (12 years) but the only one I have seen where he is talking directly to a vegetarian/vegan audience and it was completely different from his general videos.

    4. I found I feel best and more attuned to my nutritional needs when I do not take nutritive supplements on a regular basis. I drop them in here and there, when I suspect there is a need not being met by my clean, plant based eating. I was low in ferrous because I have been a veggie eater for years…until I started cooking/braising my vegetables in CI. Could it be Cast Iron is imparting iron into my diet? I also developed a strong desire to eat Brussel Spouts blacked with with a touch of molasses tumetic, black pepper and garli a …almost a meat flavor. Who knows about this? Am I wrong to trust so much in cravings as being nutritional deficient tells?

      I read someone describe themselves as
      being an intrutive eater which resonated
      with me since ten years ago, when I first
      tasted arugula, I liked it, but my CELLS LOVED IT. I developed what could only be described as a instant addiction. When I could not always find it to buy to eat daily, I found out how easy it was to growl, I broadcast seeded my garden, lawn and that of my neighbor’s.

      Wowza! Something powerfully magical could be felt happening within me. It was still years until I discovered I was uber toxic with mercury, aluminum, tin and, BIG Time with fluoride and as of yet knew nothing about detox pathways.

      I suspect I may not have the genetics to detox via the methylation pathway, but I sure must via the NO2 detox pathway!!! Guess what is one of the highest scources of NO2–ARUGULA!!! Because this is a super scource of NO2, it is now neing toted as Green Viarga.

      While I am at it, my other strong food addictions I know where somehow from need, were cashews and 100% dark chocolate. Could the pirating of receptor sites by these toxins be, at least in part, causing these strong needful craving?I also have had strong craving
      for both lemons and pineapple…what could that be? And why do I put tumeric
      in and on everything?

      Sorry for all these questions. It took decades of recovering my wit, wherewithal and cognitive functioning skills.
      Thank you for your patience with me as I strive to recognize the physiological effects of what these toxins have meant to my health. I am ever grateful for Dr. Gerger and his, “How Not to Die”, “How Not to Diet”, and the wise and talented volunteers who help Dr. Gerger keep the, “TRUTHS ‘A ROLLING IN.” I very much attribute my recovery from being uber toxin poisioned to an answered prayer, an all natural healing protocol and your guidance into knowing FOOD IS PREVENTATIVE MEDICINE.

      1. Intuition often does not correspond with reality. “Intuition” is what led to Voit stating that humans must need 118 grams of protein per day (wrong) because that’s what working men ate. Furthermore, I’ve actually had more than one patient tell me they “needed” cigarette smoke for their health. You will not necessarily know if you are deficient in something like B12. When in doubt get tested. And yes, cooking in an iron skillet can provide you with some iron.

  4. What about l-carnitine injections – bypass the gut altogether? I eat totally plant-based so wouldn’t consider but apparently l-carnitine supplementation can be a very effective form of treatment for some conditions.

    1. The use of isolated supplements doesn’t have a good track record as a recommendation for general populations. Injections which by pass the gut also by pass the liver which is one of the bodies defense and detoxifying organs. I would be doubly careful about injections therefore. That said the use of carnitine has shown some promise in treating some neurometabolic disorders but the jury is still out. Keep tuned to as the science keeps coming.

  5. Do we know how long one needs to be on a vegetarian diet before CPT is unregulated? I’m at the 6 months mark of mostly vegan, super clean, organic, unprocessed vegetarianism, moderate exercise and still no weight loss.

    1. alohadawn: Sounds like you are on the right track to me. Congratulations on the changes you have made so far.

      You are not alone. While most people seem to get the benefit of weight loss after converting to a whole foods plant based diet, not everyone does. Dr. Forrester, who often comments on this website, clued me into two wonderful videos which together do a good job of explaining why some people need to tweak their diet a bit further in order to experience weight loss. And how to do it.

      The first video is available free on line on youtube:

      The second video must be purchased, but I think it is worth it. I personally got a lot out of this video.

      Good luck to you. I hope this helps.

  6. I have been a vegetarian for seven years! Just recently I became vegan and eat an 801010 lifestyle! In the past few years I gained 40 pounds! Any suggestion on how to get rid of stomach fat? I had a flat stomach most my life!

    1. As Thea mentioned Dr. Lisle’s video is a great place to start. The important concept is Calorie Density. The best explanation for that is a video by Jeff Novick entitled, Calorie Density: Eat More, Weigh Less and Live Longer. Another useful resource for my patient’s is Dr. McDougall’s Dec 2008 newsletter article entitled, Fat Vegan. Calculating calorie density (i.e.
      calories/pound) is straightforward using the free website, CRON-O-Meter. After
      signing in, click “add food”. Enter the food you are interested in in the “Name”
      box then select the specific food from menu. At the bottom next to serving
      enter 454 (the number of grams in one pound) then select “g” for grams and click
      “add serving”. The resultant display will give you information about one pound
      of that food (e.g. kcal, protein, carbs, fat, vitamins, minerals). The number
      of kcal is the calorie density. Once you understand the concepts and make the adjustments in your shopping and eating habits you should be on your way to achieving a healthy weight. Based on my experience realistic goals are between 1/2 and 2 pounds per week depending on calorie density and exercise. Good luck.

  7. What about choline? The Linus Pauline Institute has found it important to many parts of health, including avoiding fatty liver, metabolic syndrome, fetus and infant health (for their whole life), and correct cholesterol . . . but it is found greatly in liver and eggs. I’m not vegetarian or vegan, but others here are, and I’m not happy with daily beef liver or four eggs (!!) just to get what I need.

    1. Oceanally: Congratulations on giving up the red meat. I hope you are able to make it the rest of the way for cheese and eggs.

      I don’t know that a little sugar in your diet is a major problem. However, eating a lot of junk food, which usually is how we imbibe our sugar, is a big problem. So, if you feel that you need to clean up your diet some more and want some tips, I highly recommend the following book: “Breaking the Food Seduction, The hidden reasons behind food cravings – and 7 steps to end them naturally” – by Dr. Barnard. Dr. Barnard understands the power and health value of plant based eating. All of the advice in the book has good scientific backing. And the back even has easy to follow recipes.—-Naturally/dp/0312314949/ref=sr_1_1_title_0_main?s=books&ie=UTF8&qid=1410302487&sr=1-1&keywords=breaking+the+food+seduction

      Good luck!

  8. Hi Dr. Greger,
    Thank you for your work!
    I am a 43 year old woman and I am within my ideal weight range. However, I would like to be 5-10 pounds slimmer. I recently recommitted to a completely vegan diet (plus I watch my sugar intake, seldom eat processed foods, and cut out alcohol and dessert) and I gained weight. I started counting calories while keeping my food choices vegan. With calorie awareness, my morning bowl of steel cut oats, ground flax, hemp seed, chia seed, natural peanut butter, and rice milk was cut by about 70%. I haven’t lost much weight and I’m constantly hungry. I’m moderately active – I walk about 4 mph on an incline about 5 days a week for an average of 45 minutes.
    Perhaps I’m crazy to think I should be slimmer, but I don’t think so. I know my meat eating friends would say I’m hungry because I’m not getting enough protein and fat, but I really don’t want to believe that.
    Just wondering what your thoughts are about this.

    Thank you,

    1. b: I can’t comment on whether or not it is a good idea for you to loose weight. To my way of thinking, everyone should get to their own personal ideal fat percentage and not try to go over or under that. I am deliberately saying fat percentage and not weight, because it is important to note that weight includes muscle and while more muscle mass = more weight, it is a good thing. Something about your post made me think this was worth bringing up.

      So, : if you currently have more fat than you really should, then you should also be able to safely loose that fat without going hungry or doing so much calorie counting. I think the following resources would help you figure out how to do that.

      The first is a free lecture on You Tube from Doug Lisle, Ph.D. called, How To Lose Weight Without Losing Your Mind

      While you have to purchase it, I also *highly* recommend that you watch the talk from Jeff Novick called Calorie Density: How to eat more, weigh less, and live longer.

      I hope that helps.

  9. Hi there, I am a 15 year old girl who is currently dealing with an eating disorder. I am currently eating a mostly vegetarian diet of about 1350 calories. I am at a weight that I want to maintain, and currently am on this amount. However I would like to be able to maintain on a higher calorie intake without gaining. Is this possible? Im really lost and need help

    1. Kat, I am very sorry to hear about your eating disorder. My girlfriend has gone through one in her past so I understand the struggles. Your situation is a complex and serious issue im afraid no one here is fit to handle or should handle, especially through the internet. I would encourage you to visit a dietician who specializes in eating disorders, as that is a very specific field most doctors and regular dieticians are not fit to handle.

    2. Kat: Your post is really interesting in that you are at a weight you like, but want to eat more calories. The question is: *Why* would you like to eat more calories? I’m guessing that what you are really wanting is to be able to eat more food. Yes? In other words, is the food you are eating now not filling enough? Do you get hungry? (Or do you feel full and the desire for more food is related to your eating disorder?)

      Depending on what you are eating now (saying “a mostly vegetarian diet” doesn’t tell us much), you might be able eat more food volume-wise while still eating the same number of calories and still not gain weight–and also increase the healthieness of your diet to boot. Eating the types of food I am talking about, could make you feel more full. The key to doing all of this is to understand what healthy food actually is AND to understand the concept of calorie density and how to apply it to your diet.

      I can give you some references (including a great video) that would help you to understand what calorie density means and what a healthy diet looks like. But before I do, I want to know if I would be addressing your real concern (not more calories, but eating more food because you feel hungry all the time?)? And also I will repeat what Toxins said in terms of: If your issue of wanting to eat more food and feeling hungry is tied up with your eating disorder, then maybe researching calorie density is not the way to go for you. That would be beyond the scope of any help I could provide.

      Would you like more information? (And either way: I wish you luck. Good for you for addressing your problems right now instead of waiting down the line like so many others do!)

  10. from the source sited: ” reduced collagen synthesis” in vegetarian.. “lowered collagen synthesis (-10%).” It is not collagen important for joins cartilage , tissues and skin ? thank you!

  11. There are so many discussion about that. Some people say that there are people out there who have to restrict calories to lower their weight. Some people say you sould never do that and stop restricting. So which one should I believe? I was aways restricting my calories if I wanted to loose weight. It never worked long term. After a long time of being fep up with restricting I ate more and suddely I’ve lost weight. And now I hit a weight plateau. Maybe increasing my intake is fixing that?

  12. I am doing research about meat and diary and i have important question about CPT. It is originaly synthesising in our bodies but omnivores get it from flesh of other animals and diary. So why Vegetarians have more CPT during much more consumption of CPT in Omnivores?

  13. Hi, robertzmys. I do not know the answer to your very interesting and complex question. Maybe there is a difference between the CPT ingested in food, and that which is endogenously produced in terms of metabolic effect. It is also possible that those who consume CPT produce less of their own CPT. This is pure speculation, of course.
    You might be interested in this article:
    If you find the answer to this question in the course of your research, please come back and share it here. We would love to know what you find!

  14. Hi Dr. Gregor,
    I am a Health Coach and CMA and work at Verity Primary Medicine & Lifestyle. The doc I work for is Lori Carnsew MD and she has just come back from taking the Lifestyle Medicine Boards. I am so jealous that she got to hear you speak again but I do hope to join her for the next trip! I just wanted to say thanks for all you and your team do, having trust worthy information is priceless!
    Back to my question; When a women is no longer able to nurse a baby what is the best option for the bottle? For example, if the mom has been able to provide her milk for at least 6-8 months and the baby is eating fruits and veggies 2-3 times daily is almond milk and vitamins acceptable? I have been researching but have not found any real evidence of “the best substitute” for mothers milk. The ingredients in formula do not make good sense to me and sometimes mothers just cannot nurse. Do you have any advice in this area? I have seen many mothers feel inadequate because of this dilemma but it is a real fear of feeding the wrong or even damaging “milk”.
    Thanks in advance for any information offered!
    Tina Moss

  15. Tina,

    Glad to hear that your employer has the interest and desire to see the whole picture for her patients.

    To address your question, after 6-8 months the majority, not the totality, of the breast milk feedings impact has been achieved. The immune system and maturity of the gut are well underway.

    Almond milk should not be considered in any way a substitute for breast milk, but rather as a good form of hydration. You might consider formulas such as the European formats that more closely mimic breast milk such as: Holle or HiPP or an elemental formula as some considerations when looking at alternatives.

    I’m also a big fan when breastfeeding is not an option, of other mom’s milk. You can find many organizations that will facilitate this exchange.

    Dr. Alan Kadish moderator for Dr. Greger

  16. Hi – I want to understand how the two systems “split the bill” when it comes to digesting fiber-rich foods that are also fatty (like nuts, and for the sake of argument, lets say GROUND flaxseeds).
    Is this food digested via FAO (fatty acid oxidation) in the mitochondria, or via the microbiome providing the body with SCFA (short chain fatty acids). And to which extent?
    When there is a limit to achievable FAO (certain diseases) this becomes very important.
    How do I find more data on this?

  17. Hi Jenny,

    I am a volunteer for Dr. Greger. Thank you so much for your question!

    This is how fat is digested and absorbed into the body: fats are digested in the stomach and small intestine, and then packaged and absorbed into lymphatic system, which transports the fatty acids to the blood stream for cells to pick up for energy (beta-oxidation–or as you are calling it, FAO) or to be stored as fat. The fat that does not get absorbed (typically from WHOLE, not ground, nuts) goes down to the large intestine. Much of these small, but whole pieces of nuts are actually passed through without being metabolized (i.e., end up in the feces). However, there may be some that is utilized for energy by certain bacterial species. Although the mechanism by which this occurs is not fully understood, this likely favorably shifts the ratio of “good bacteria” to “bad bacteria”, resulting in the increased metabolism of phytochemicals that make their way to the gut bacteria into short-chain fatty acids, which are beneficial for human health.

    The extent to which the pieces of nuts/seeds enters the large intestine is primarily determined on how well the nuts/seeds are broken down mechanically (either by chewing, blending, grinding, etc.). The large pieces are unable to be broken down and thus, unable to be absorbed. I am not sure that we know how the consumption of ground flaxseeds influences this process.

    Here is one paper on how walnuts influence the gut bacteria:

    This is a great paper with an IN-DEPTH look at how nuts (and various food compounds in nuts) influence gut bacteria:

    I hope this helps, even though it is a bit confusing. There is so much we don’t seem to know about this yet.

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