Why the Body Set Weight changes EVERYTHING about weight loss| Jason Fung

insulin resistance, diabetes, blood sugar, weight loss

I’m diving into the fascinating concept of the body’s set weight, which acts like a thermostat for our body fat. Ever wondered why it’s so hard to lose or gain weight? I’ll explain how this body fat thermostat changes everything you know about weight loss.

In this video, we'll cover:
Body Set Weight – Understand how your body controls fat like a thermostat.
Homeostatic Mechanisms – Learn how our bodies automatically adjust to changes.
Calories vs. Hormones – Discover why “calories in, calories out” isn't the full story.
Real-life Examples – See how historical figures stayed fit despite food availability.
Scientific Studies – Explore research proving the existence of this body fat thermostat.
Hormonal Influences – Find out which hormones affect your body’s set weight.
I’ll break down complex ideas with simple examples, like comparing your body to a room with a thermostat. Whether you’re trying to lose weight, gain weight, or just understand how your body works, this video is packed with easy-to-understand information.

Don't miss out! Hit play and learn how to adjust your body’s thermostat for better weight management. Remember to like, subscribe, and leave a comment with any questions or topics you want me to cover next.

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▶️ Timestamps/Chapters
00:00 intro
00:27 body set weight “ Body Fat Thermostat “
01:32 Homeostatic Mechanism
03:01 obesity is not caused simply by easily available food
04:20 how many calories we eat?
04:23 how many calories we burn?
05:33 why does the existence of this body set weight really change everything about weight loss?
06:54 where it doesn’t work as when we start to put in the existence of the thermostat?
08:44 the question is this does it actually happen in real life?
10:08 outro

👉 The Obesity Code – Reviewing underlying physiology of weight loss and how low carb diets and fasting can help. ?…

👉 The Diabetes Code – Reviewing how type 2 diabetes is a reversible disease and dietary strategies. ?…

👉 The Cancer Code – Scientific exploration of how cancer develops – ?…

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#ExplainingTheBodyFatThermostat #TheBenefitsOfFasting #FastingWeightLoss #IntermittentFasting #BenefitsOfFastingForTheBody #BenefitsOfFastingForTheBody #CuttingCalories #FastVsSlowCarbs

Cameron Long

  • @mayau0219 says:

    Hi Dr. Fung,
    I followed your advice about intermittent fasting. I lost 15 pounds in 3 months. My A1C from 6.3 to 5.8. I appreciate your time and effort to make these videos on YouTube ! Thank you for your help 🎉

  • @queensizedfun1 says:

    🎉 I get too excited when I get a notification of a new video of yours.

  • @mandys6525 says:

    Thank you Dr. Fung. Your analogies are so helpful.

  • @PioLisieux says:

    Thank you for making these videos
    and NOT charging for the info Dr. Fung!

  • @098anne says:

    Thanks, Dr. Fung! Please focus on the HOW next time 🙂

    • @LuvlyDaze says:

      He has lots of other videos on the “how”.

    • @amethystfeathers7324 says:

      ​@@LuvlyDaze….it would be useful if they were linked then for people, like me, who are first timers listening to him..

    • @tejalp2321 says:

      @@amethystfeathers7324I agree with you…this is the first time I watched a video from him about fat thermostat and I have read his Complete guide to fasting book. I guess I’ll have to get his obesity code book too

  • @billyhw5492 says:

    Any treatment for obesity that doesn’t treat the body fat thermostat is doomed to fail over the long term.

  • @LTPottenger says:

    The great thing about fasting is it actually increases the metabolism when you do fasts 96h and under. It also regenerates organs like the thyroid at the end of the fast due to growth hormone generation. Hormons like testosterone slowly wane with age but in both men and women, growth hormone reduces by 2/3 as soon as we are adults and stays that way forever for most people. The many benefits of occasional extended fasting and lowering dietary carbs:
    Your body recycles up to 1/3 of all immune cells in a 72h fast, rejuvenating your immune system. This helps with autoimmune disease, cancers and cytokine storm.

    Reduces B cells by over half in a single fast, greatly reducing allergic and other autoimmune responses.

    Fasting and low carb help with POTS, which is driven by high insulin and blood sugar.

    Fasting reduces cortisol over time and improves your circadian rhythm.

    Fibrosis aka scarring is reversed over time, including in the heart, lungs and clots.

    Clotting and fibrin are inhibited, stopping any ‘unusual’ clots.

    Fasting stimulates phagocytosis, the ingestion of proteins, pathogens and plaques by macrophages and other immune bodies. This will remove spikes quicker, whether natural or unnatural in origin!

    Fasting restores NAD+, reduces NADH and increases nitric oxide release to open blood vessels.

    Reflexes and short term memory are increased.

    Fasts from 36-96 h increase metabolic rate due to norepinephrine release!.

    Blood sugar and insulin are lowered when fasting, reducing inflammation and allowing the immune bodies to move freely through the body.

    T cells are cruciall in fighting cancer, autoimmune disease and infection. With age, the thymus generally stops making them but fasting releases stem cells, which then can become new T cells. It also releases growth hormone, which regenerates the thymus!

    When insulin is high, vit D stays locked in the blood cells but fasting quickly lowers it. Vitamin D plasma levels are increased as fasting improves metabolic health, and D in turn increases autophagy.

    Fasting increases anti-aging Yamanaka factors and increases average telomere length in stem cell pools.

    Fasting increases interferon, which shuts down the ability of viruses to replicate.

    Clots and plaques are removed over time due to accelerated phagocytosis.

    The hunger hormone ghrelin also lowers with extended fasting and rises from dieting.

    Fasting does not reduce testosterone over time. Iraises it when the fast is broken by increasing lutenizing hormone. Fasting also increases insulin sensitivity, which helps with muscle building. And removes fat, which also increases estrogen in men.

    Fasting activates autophagy (literally self eating). This recycles damaged proteins and foreign matter such as viruses.

    Fasting can help with MS, Depression, BPD, Autism and seizures.

    Weight loss from daily caloric restriction has 1/4 to 1/3 of the weight lost as lean tissue while many studies show fat loss from 36 h fasts without losing any lean tissue!

    The obese will lose loose skin while fasting, but the frail will have increased growth hormone release, which helps to make more lean tissue and reduce frailness.

    It increases mitochondrial function and repairs mtDNA. Mitochondrial function also has the added benefit of increasing your metabolism, fighting infection and cancer prevention!

    24h of fasting reduces leptin levels by half! This reduces leptin resistance, which impairs immune function.

    Over time fasting normalizes stomach acid levels and during the fast acid levels go down to allow for the healing of ulcers.

    Fasting reduces pain and anxiety by stimulating the endocannabinoid system, just like the effect of CBD oil

    Your brain prefers to burn ketones at a rate of around 2.5 to 1 when equally available to glucose. Except for brief periods of very intense exercise, your body mainly burns free fatty acids.

    When not in ketosis, the brain can only burn glucose, which produces a great deal of damaging ROS the brain has to deal with.

    Fasts of 36-96 will not affect short term female fertility or affect menstrual cycle. They also may increase long term fertility for some women.

    Fasting releases BDNF and NGF in the blood, creating new nerve and brain cell growth. This helps a great deal with diseases like MS, peripheral neuropathy and Alzheimers.

    Fasting stimulates apoptosis in senescent or genetically damaged cells, destroying them. Senescent cells are responsible for many of the effects of aging and are a root cause of the development of cancer.

    Glycine and trimethylglycine (TMG) can also be useful supplements while fasting that won’t break ketosis and have many benefits.

    A fasting mimicking diet for 3-5 days in a row provides many of the same benefits as water fasting. FMD has about 200-800 calories, under 18 g of protein and zero net carbs.

    What breaks a fast? Anything with protein or carbohydrates in it will break a fast but most teas and herbs are OK. Supplements and meds usually break ketosis directly or contain a filler that wil, or irritate the stomachl. Many meds are dangerous to take while fasting.

    Exogenous ketones can aid with fasting, allowing some people with specific issues to fast in spite of them without worrying as much about hypoglycemia. They also help with dementia and many other issues even if you take them while not fasting!

    Children, expecting or nursing women should not fast for periods longer than 16 hours. People with pancreatic tumors that excrete insulin or certain rare forms of hypoglycemia generally cannot fast at all or only with doctor supervision. T1 diabetics can also fast but it is more complicated and should be approached with caution as it could lead to ketoacidosis and done under doctor supervision. If you experience extreme symptoms of some kind, especially dizziness or tremors, then simply break the fast with a low carb meal.




    This list compiled over years of research by the user known as Pottenger’s Human on youtube. Feel free to copy and paste this anywhere you like, no accreditation needed!

    • @iamsmartmethinks says:

      I want to copy this, can you please reply so it pops up in notification? Thanks!!!!

    • @LTPottenger says:

      @@iamsmartmethinks It’s also on my community tab. At some point I will put it on a pdf if I can get a website to do it where the link will be permanent.

    • @NiceLoki says:

      Far FAR TL:DR

      Wall of text vomit.

    • @LTPottenger says:

      @@NiceLoki No one forced you to read or wanted your opinion

    • @NiceLoki says:

      @@LTPottenger You might want to rethink your public interactions if you’re trying to build a customer base.

      If you can’t take even a basic level of criticism then probably in the wrong industry.


  • @dianajohnson6824 says:

    Dr. Fung makes everything understandable and I really enjoy his info. Gotta get the book The Obesity Code!!! Thank you.

  • @hoovergrant says:

    Post menopausal, Intermittent faster here, now for 28 months. I lost 19% of my body weight in the first six months however my set point wanted me to weigh slightly more and I now accept that my body is happier at a slightly higher weight. I’m at goal and weigh about 16% less from the time I started intermittent fasting. I’m down three pants sizes and I take my body measurements once a month. Thank you for your channel Dr. Fung intermittent fasting actually is pretty easy to do. I think of it as a light switch, on or off, eating not eating.

    • @MarinaLaroche says:

      What is it you do ? 16/8 ? 24, 36, 48, 72 Hrs ? Thanks.

    • @hoovergrant says:

      @@MarinaLaroche Hi Marina, I started IF, intermittent fasting doing “OMAD”, one meal a day. I did that until I got to my goal weight which was lower than I am now. So after I got to my goal weight I switched to 2MAD, two meals a day. Some days I still do OMAD, just depends on how I feel that day. I try to not eat before noon which means I’ve fasted from roughly 15-18 hours from the previous day. I drink black coffee in the morning, that was hard for me because I always drank coffee with 1/2 & 1/2. Now as a treat I’ll drink my coffee with heavy whipping cream and it’s divine! I also drink a lot of plain seltzer water with lemon or lime in it and I did that from the beginning. Yesterday was July 4th and I gave myself license to eat all that I wanted. I met friends for breakfast at 8am and had a giant Mexican breakfast of chilaquiles, dinner was at 7pm. We ate bratwurst on buns with homemade coleslaw, french fries, raspberry sorbet with Trader Joe’s ginger snap cookies and wine before, during and after dinner. I hope this is helpful to you, you can do it Marina! By the way I just had a physical with tons of blood work, A1C…perfect, blood pressure…perfect, cholesterol…perfect.

    • @MarinaLaroche says:

      ​@@hoovergrant Thank you for such a detailed reply ! I’ve been strict keto for years now. It’s always great to hear of people’s good results !

    • @MarinaLaroche says:

      @@hoovergrant Reread your first post and see you’re part of the Menopaused world too lol.

    • @hoovergrant says:

      @@MarinaLaroche I don’t understand, reread my first post? I thought saying post menopausal stated that I am woman, born as, identify as.
      Anyway, I know a number of people who have done and do keto. Personally it would be impossible for “me”, to repeat, for “me” to follow a keto diet.
      I love meat but I’m also a very broad eater and could not imagine excluding categories of food or even an individual item of food. Maybe consider a “diet break” for a couple of weeks. I picked up that expression from YouTube, trainer Mike Cola.

  • @Jacquie_Kirk_111 says:

    Another great video from the GOAT Dr J Fung!

  • @BeeBubbaBella says:

    Back in 2018, I read The Obesity Code as I started my Keto journey. I have referred many people to it because of the information on body set weight. For those wondering the how to reset your body set weight, you should read Dr. Fung’s book. He also talks about it on previous videos. I’ll give you a hint. It involves intermittent fasting. 😊

  • @Nyt250 says:

    Dr Fung is a brilliant doctor and has helped so many people. Keep doing what you’re doing, doctor. Much respect.

  • @JohnsonNestorFamily says:

    Hi Dr Fung! Thanks for posting this video. Really important information for weight loss and maintaining weight loss.
    I’m 61 and lost 160 lbs by finding and following your videos, interviews, lectures and books. It reversed ALL my health issues. I’m maintaining well but I found it challenging to learn how to maintain once I met my goal weight. Maybe a video about maintenance? I feel the best I ever have and I’m loving my fasting lifestyle! Thank you so much for all you do for us! 🙏😀💪

    • @angelgirldebbiejo says:

      Do the intermittent fasting every day like 16/8

    • @michaelr.maxwell9437 says:

      what type of fasting did you do to lose all those pounds? How often do you fast? I need to lose 50 pounds.

    • @JohnsonNestorFamily says:

      @@michaelr.maxwell9437 Hi! At first , I just gave up ALL refined carbs and sugars. And increased my natural ( saturated) fats. Then I ate LCHF keto ( low carb high fat) and OMAD ( one meal a day) then skipped a day entirely once a week. I still eat healthy ” ketovore” leaning more towards meats, eggs, fermented veggies (kimchi/sauerkraut etc) and some nuts and seeds etc. Read Dr Fung’s The Obesity Code. It will explain everything so well. You can watch my story on The Magic of Fasting YouTube channel 😊. I also have just started my own channel you can link to from my name tag. Thanks again and be well 👍🙏💪

    • @JohnsonNestorFamily says:

      @@michaelr.maxwell9437 Hi! At first, I gave up ALL refined carbs and sugars. And increased my natural, saturated fats. Then I did OMAD, one meal a day, then started skipping a day entirely once in awhile. It became naturally easy to do!
      Now , I’m more ketovore, and eat every other day and throw in longer fasts now and then. I’m active, swim, and am maintaining great 😃. Please read Dr Fung’s book The Obesity Code. It explains everything so well. Thanks, good luck and be well 😊🙏

    • @JohnsonNestorFamily says:

      @@michaelr.maxwell9437 Hi! Please read Dr. Fung’s book The Obesity Code. It explains everything so well.👍
      Give up ALL refined carbs and sugars and increase your natural, saturated fats. Then I did OMAD, one meal a day then skipped a day now and then etc. Now, I eat ketovore, eat every other day and do longer fasts also. I’m maintaining great, am active, swim and am so thankful 🙏. Thanks again and be well 😊

  • @missyleonis says:

    2 things adjust the body thermostat aside from excersising. 1 intermittent fasting. 2 adjusting the kinds of foods you eat and ratios. This means ditching seeds oil, minimizing carbs as much as you need on a individual basis, upping protein. If that isn’t enough, up fat intake with healthy fats like animal fats, butter, ghee, olive oil or alvacado oil as long as not heated, coconut oil, sesame oil. Nuts, seeds, alvacado, olives, cocoa nibs, cheese, eggs, fatty meats as well as lean meats, are all good fats to have. Focusing on mostly whole foods helps too. Adding in fermented foods helps reset things.

    These are the best ways to reset metabolism. Not saying everyone has to even eat a ketogenic or carnivore diet though I did for almost 2 years. But some form of low carb, primarily whole foods, seed oil free, antiinflammatory diet does the trick. That can be keto, ketovore, carnivore, Paleo, Mediterranean, or any form of low carb you create individually. I’m doing my own version of low fodmap general low carb no real guidelines but below 100 g carbs a day, usually between 60-70 g total but under 50 g net currently. Some people do well on less, some on more. Hense my individual needs comments.

  • @WESTNORTH123 says:

    Thank you Doctor. You are a saviour.
    A1c from 9.6 to 5.2 in 3 months.
    Weight loss 12%

    Intermittent fasting 12hrs a day
    Carb moderation
    walking / cycling 3 times a week

  • @BMO_Creative says:

    Yessir! Gotta recomp your set “normal” fat level. Only way to lose fat and keep it off. The general media NEVER mentions this.

  • @musicalessence3936 says:

    Dr. Fung…… what a tease you are!!!! Now I’m gonna get this book finally so I can understand how to lower my set point!! I’m on OMAD at only30 grams of carbs trying to lower my A1C and loose weight. You’re amazing and my great health today is due to your videos….. you help thousands and thousands of people! What a soul you are! ❤

  • @daedalduo says:

    Fasting is the ultimate tool for hormonal control for the body fat thermostat. Brilliant video, Dr. Fung!

  • @pamisntcraiganymore says:

    Good reminder Dr. Fung. I got my fasting groove back. I have reestblished a 36 hour fast today. Today as I was feeling hunger I thought of you and reminded myself that this is just my ghrelin getting turned up.

  • @roylereg22 says:

    Whoah..amazing content. This explains a lot..i am grateful for this channel Dr. Fung!

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