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How to Upregulate Metabolism

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

October 20, 2009 |
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Supplementary Info

Sources Cited



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 meateaters. 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 is 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 Palmitoyl Transferase. 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.

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Dr. Michael Greger

Doctor's Note

Please feel free to post any ask-the-doctor type questions here in the comments section and I’d be happy to try to answer them. And check out theother videos on vegetarians. Also, there are 1,449 other subjects covered in the rest of my videos--please feel free to explore them as well!

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

  • Michael Greger M.D.

    Please feel free to post any ask-the-doctor type questions here in the comments section and I’d be happy to try to answer them. And check out the other videos on vegetarians. Also, there are 1,449 other subjects covered in the rest of my videos–please feel free to explore them as well!

  • ARC

    What is your present considered opinion on the consumption of good fats by healthy people?


    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

  • Xgabrielzx

    The article cited in the video seems to say that the vegetarian diet is bad for people..

  • Susan

    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?

  • Denise

    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?

    • Toxins

      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)

      • Denise

        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.

    • Christina

      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.

  • Paul Spring

    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.

    • Don Forrester MD

      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.

  • alohadawn

    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.

  • Lori Sassen

    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!

    • Don Forrester MD

      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.

      • Lori Sassen

        Yes, I already used cronometer! Thank you!

      • Lori Sassen

        Unable to find video Jeff novick put out on calorie density have looked for 40 mins!