Doctor's Note

This completes my seven-part video series on this fascinating phenomenon. I began by reviewing the balance of evidence on why nuts don’t tend to contribute to weight gain in Nuts and Obesity: The Weight of Evidence. I then introduced two theories on Solving the Mystery of the Missing Calories, both of which were put to the test in a study on peanut butter, Testing the Pistachio Principle. Next came Testing the Dietary Compensation Theory, an elegant study using walnut smoothies, followed by the big reveal in Testing the Fat-Burning Theory. But why might nuts help you burn more fat? Arginine is one possibility (see Fat Burning Via Arginine), and today’s video on flavonoids presents another. For more on flavonoid phytonutrients, see Phytochemicals: The Nutrition Facts Missing From the Label. For a comparison between fruit juices, see Best Fruit Juice, along with a video on putting that knowledge into practice: Pink Juice with Green Foam. Which beverage has the most antioxidants, though? See Better Than Green Tea. And what about juiced vegetables, such as carrots and beets? See Benzene in Carrot Juice, and an entire series starting with Doping With Beet Juice. And for more on the wonders of Concord grapes (yum!), see Repairing DNA Damage; and Plant-Based Diets and Cellular Stress Defenses

For additional context, be sure to check out my associated blog posts: Nuts Don’t Cause Expected Weight GainIs Caffeinated Tea Really Dehydrating?Burning Fat With FlavonoidsDo Vegans Get More Cavities?; and Flax Seeds for Diabetes.

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  • Michael Greger M.D.

    This completes the seven-part video series on the fascinating phenomenon of Solving the Mystery of the Missing Calories. I started our reviewing the balance of evidence of why nuts don’t tend to contribute to weight gain in Nuts and Obesity: The Weight of Evidence, introduced two theories on Monday, both of which were put to the test in a study on peanut butter Testing the Pistachio Principle. Then came an elegant study using walnut smoothies, followed by the big reveal in Testing the Fat Burning Theory. But why might nuts help you burn more fat? Arginine is one possibility (see Friday’s video-of-the-day Fat Burning Via Arginine) and today’s flavonoids are another. For more on flavonoid phytonutrients, see my video Phytochemicals: The Nutrition Facts Missing From the Label. For a comparison between fruit juices, see Best Fruit Juice along with a video on putting that knowledge into practice, Pink Juice With Green Foam. Which beverage has the most antioxidants, though? See Better Than Green Tea. And what about juiced vegetables such as carrots and beets? See Benzene in Carrot Juice and an entire series starting with Doping With Beet Juice. And for more on the wonders of concord grapes (yum!), see Repairing DNA Damage and 
    Plant-Based Diets and Cellular Stress Defenses. If you haven’t yet, please feel free to subscribe for free to my videos by clicking here.

    • HemoDynamic, M.D.

      Peel me a grape, crush me some ice,
      Skin me a peach, save the fuzz for my pillow.
      Talk to me nice, talk to me nice,
      You’ve got to wine me and dine me!

      Don’t try to fool me, bejewel me!
      Either amuse me or lose me,
      I’m gettin’ hungry, peel me a grape!

      Lyrics by Dave Frishberg 
      rec by Anita O’Day  ’62

      They knew the power of plants in 1962! Although they should have eaten the skin.

  • LKSkinner

    This is great news here. I’m always happy to see positive results that come from regular, everyday food that anyone can find and eat.
    No nutritional mumbo-jumbo here, just good food and good nutrition.
    The sort of nutrition that must drive the health food manufacturers crazy, you can’t sell high-priced magic pills when informed consumers know they can eat FOOD and get healthy.

  • LKSkinner

     This is great news. I love it when regular foods, like green tea, grapes and nuts are the heroes of nutrition, not expensive, manufactured pills.
    This must drive the health food manufacturers crazy, or, should I say nuts?

  • Nice one! This series sort of reminds me of the coconut folks who claim the fat-burning of coconut  oil. I understand coconuts aren’t the most nutrient-dense of fats, and, certainly, the oil isn’t healthful to consume; however, I do think there may be some truth to at least parts of the claims.

    Love the picture of the concords. Those are the best tasting grapes! Gotta go look for some now. Loving all the fruits this month — FIGS too!

    Great series, Dr. G.! Thanks a million ;^)

    • Elvin

      Strix: I wonder if you would be so good as to give a
      answer to the question asked of you once by April Lillie
      and then by myself on
      page ‘The Best Way to Boost Serotonin’.

  • Basically, eating foods that are dark purple, deep red, and deep green (tea) is the key.

    • Valnaples

      “deep green”…=DINO KALE(such a dark green, it’s almost black)?? “deep red”….=cranberries?  just throwing other possibilities in there.  thank ya!

  • Spam Guard

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  • Taranis

    The latest fat burning food appears to be green coffee. Is there any truth to this? If so could it also be due to flavonoids?

  • Real World Vegan

    your concord grape juice link appears to be broken dr greger. every study ive reviewed that shows statistically significant benefit to plant pigments was from highly concentrated supplements & not whole food. [i dont find any whole food studies with this video either]. & tho it cant be dismissed altogether without review, the study was funded by welches and appears to be the only study of its kind showing benefit which makes it even more questionable.

    i luv nuts but the argument is a little specious considering theyre so high in fat. fat is great at producing satiety since the stomach has to wait for the bile action before it can fully empty.

    • Joseph Gonzales R.D.

      Thanks! I am fixing it now. Will reply to other comments above thanks for your post (although I am two years late to reply) ;-) There has been more videos on nuts since. Let me know if you have not seen the latests videos on nuts and body weight.

  • Kelsea

    Hi Dr. Greger,
    I’m in a biochemistry class and I just read that high insulin levels, like after a meal containing carbs, enhances lipoprotein lipase activity, which increases the rate of storage of TG in adipose and uptake of free fatty acids into the muscle. If this is true, would it be wise for someone trying to reduce body fat to not mix carbs with fats? I usually eat a high carb meal with a little avocado or something in it, but by having so many carbs is my body telling my fat cells to store as much of that fat as possible? Before I was under the impression that glucose is the first fuel desired and therefore the fat would kind of just fall to the wayside. Thanks for your help!

    • Joseph Gonzales R.D.

      Fat burns in the flame of carbohydrate! It takes a lot of energy for carbs to get stored as fat. Only in excess does this happen. I’ll write more in the above posts. Thanks, Kelsea

  • ThePlantLife

    I eat a high carb (80% of total calories) low fat (less than 10% total calories) whole food plant based vegan diet and I exercise about 3 or 4 times a week. I am healthy, but I’m about 10lbs over my ideal weight, and have discovered a large community of YouTubers who claim that it is “impossible to gain weight from whole food carbohydrates” and that you can eat as many carbs (from whole plant foods) as you want and still loose body fat. These people eat upwards of 2500 (often 3000+) calories a day, yet they weigh around 110-130 lbs and do moderate exercise 3 or 4 times a week. There are other YouTubers who claim that they gained weight eating that many calories of carbohydrates with a similar low fat, plant based diet. It seems as if some people’s metabolisms are crazy high and can “burn off” the extra energy with something they call “dietary thermogenesis”. And yet it also seems as if other people’s metabolisms don’t work this way, and store the excess calories from carbohydrates as body fat. The people who claim it’s possible say that the massive amount of excess energy from their carbohydrate intake is stored as glycogen in muscles, not as body fat. Yet others seem to be proof that this is not the case. I am so confused as to why some of these people are able to eat so many carbs that they get a “food baby” after each meal, and yet I, for example, can only slightly similarly overeat and then notice excess fat stored around my hips and thighs. It’s important to remember that I doubt this is water retention from sodium intake, because I eat no added salt and no processed foods. I’m desperately confused.
    Is there any truth in the “unlimited carbs” theory? If not, why are these people so successful? How many carbs can you eat before they are stored as fat? How much can people’s metabolisms vary inherently? Do you have any advice for me specifically? If you are curious for an example of a “calorie stuffer” check out Freelee the Banana Girl’s channel and view some of her older videos, for example her “30 Videos in 30 Days” playlist. She is not the only one, but she is a good example of what I’m talking about.
    If anything I’ve tried to convey is unclear, please ask me to clarify or elaborate, and thank you in advance for helping me. From what I’ve found on YouTube, I’m not the only one who seems to be struggling with this inconsistency and mystery. Please help me.
    Thank you for all that you do; it is very much appreciated!

    • Joseph Gonzales R.D.

      From Dr. Greger’s book, Carbophobia, “Carbohydrates burn cleanly. In fact the name “carbo- hydrate” basically means “carbon (dioxide) and water,” which is what plants make carbs out of, and which is all the waste product one is left with when one’s body uses them as fuel. During the first few weeks of the Atkins Diet, the so-called “induction” phase, a person is forced to live off so much grease that, lacking the preferred fuel–carbohydrates–their body goes into starvation mode. In biochemistry class, doctors learn that fat “burns in the flame of carbohydrate.” When one is eating enough carbohydrates, fat can be completely broken down as well.”

      So that brings into question how many carbs are too many? From our research at the Physician’s Committee we allowed unlimited amount of carbohydrate (and food in genera)l. The diet instruction consisted of 3 parts: 1) keep it strictly plant-based (no animal products), 2) focus on lower fat foods (packaged foods under 3 grams of fat / serving), and 3) focus on foods lower in the glycemic index. Again, we allowed unlimited food so long as these instructions were followed. The results showed on average a 10 lb. weight loss after 18 weeks. Those with heavier body weights ended up losing more. Other research using this model shows similar results. Dr. Greger presents the studies I reference in these videos here and here.

      About carbs turning into fat…

      “The liver has the ability to convert glucose into fat, but under normal conditions, most excess glucose is stored as glycogen or used to meet the body’s immediate needs for fuel” From what I gather it’s inefficient and takes a lot of energy to convent glucose to fat. The last link I gave describes biochemical pathways in detail.

      Certainly everyone will vary in their ability to lose weight. One thing to keep in mind is that just maintaining weight is a good thing, at least for a few weeks. I’ve seen times when weight loss plateaus for a week or two and then picks back up. So long as the weight is not going “up” gives hope that more weight loss will occur in later weeks. It does depend on how long someone has been really trying though.

      You may try reducing your caloric intake if that’s appropriate. You could also try keeping records and using some sort of nutrition tracker. The best foods for weight loss are those rich in fiber (like beans, greens, whole grains, fruits). Dr. Greger’s latest videos tackle fat burning mechanisms as well.

      Let me know if any of these resources help? I am happy to look into what you’re eating and see where things might be improved. Keep up with the physical activity!


      • Could you just clarify this: Excess glucose is mainly stored as glycogen. Fructose is stored as fat, right? So does the body burn the excess glucose before it burns the fructose?

  • Eric

    Dr. Greger I believe I found an SIGNIFICANT ERROR IN THE STUDY DATA. Was the average waist circumference actually approximately 33cm, that is 12 inches, that’s the waist circumference of a small dog?! Seems like they must have mislabeled it as centimeters when it should’ve been labeled as inches.

  • Eric

    Dr. Greger, when I look at the data you present in this video, I can’t help but think that you and Welches, seem to be latching on to some statistically insignificant numbers when trying to support your theory that grape juice and therefor flavonoids increase fat loss In regard to the sugar group, please allow me to illustrate. Over 9 weeks, the sugar group gained 1.6kg of weight, and lost 0.3cm from their waist circumference. The juice group also gained a little weight 0.7kg and also lost a little waist circumference, 0.5cm. The real takeaway here is both groups gained a tiny bit of weight and both groups lost a little from their waist 0.5cm and 0.3cm respectively. That TINY DIFFERENCE in waist circumference between groups, over the 9 weeks could very easily be the subconscious bias of the data collectors who maybe holding the tape measure and pulling a little tighter towards the end of the study. All things considered, I have a hard time finding anything significant in this study, yet you seem to profess that this study is proof that grapes help us loose weight…. Again: Both groups GAINED weight and lost statistically insignificant circumference from their waist. Considering the study was funded by Welchs…. I can’t help but suspect that there might be some tiny bit of bias here… possibly in those who measured the waists of the studies subjects.