Doctor's Note

For some of the most recent videos on preventing obesity through plant-based diets:
Fat Burning Via Flavonoids
Nutrient-Dense Approach to Weight Management
Diet Pills Do Fat a Lot of Good
Is It the Diet, the Exercise, or Both?

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!

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

To post comments or questions into our discussion board, first log into Disqus with your account or with one of the accepted social media logins. Click on Login to choose a login method. Click here for help.

  • 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..

    • David Goldman

      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.

  • 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.

      • Comfort in CA

        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.

    • 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.

    • thaicoffee

      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.

  • 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!

    • Manuel

      Hi Lori. I could advise you. Just send me an email to:

  • Comfort in CA

    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.

    • Thea

      Comfort in CA: I don’t know about benefits, but there sure are some problems with choline. Consider these videos and articles:

      I don’t know anything about the Linus Pauline Institute. I do trust the information on this site. Good luck.

  • Oceanally

    I am 70 yrs. old and STILL addicted to sugar (gave up all meat and 90% cheese).. HELP!!!

    • Thea

      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!

  • b

    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,

    • Thea

      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.

  • Kat

    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

    • Toxins

      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.

    • Thea

      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!)

  • Noe Marcial

    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!