The Science Behind Intermittent Fasting (14 Studies) | Nutritional Science Explained

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Jeff Nippard : Ok a few quick things... Some of you may notice that I didn't include the one IF study on trained individuals in the video. I think Greg Nuckols did an excellent write up on the results and limitations but ultimately, it didn’t change the bottom line for me. I’d recommend giving his analysis a read here if you’re more interested in the LeanGains protocol or the effects of IF on trained folks: In short, it’s really likely that the fat loss benefit of IF comes down to a bigger caloric deficit. There may be improved health markers with IF, as implied from earlier studies, but they could be simply due to bodyfat reduction and we don’t know how they’d play out over the long term. There’s also some interesting new research on circadian rhythms that I just didn’t have enough time in this video to get into. Here's an interesting paper on that area: Finally, for those looking for a more practical guide, I’d recommend reading The Leangains Guide here: As always (of late anyway) I've included a full annotated list of references organized by order of appearance in the description box. Hope you enjoyed the video and I’ll see you guys again soon. Peace!

Drew Kocak : The best diet is the one to which you can adhere. Yesss 💯💯

Rob Lipsett : Quality info and editing as always man. Easy watching!

Stephanie Buttermore : Editing getter better and better babe... HOT FIRE 🔥🔥🔥

senorgato70 : You mentioned nothing about insulin sensitivity and growth hormone secretion during IF, not to mention the effects of exercising during your IF window vs. your eating window.  Those are VERY important factors to consider, especially for those working out.

David Hensel : I feel like so many people freak out about the thought of a 16 hour fast, but then forget that an 8 hour eating window would be breakfast at 9am, lunch at 1pm, and dinner at 5pm. Boom, you're intermittent fasting.

Abby Pollock : Great vid Jeff 🙌 Ive been practicing IF for nearly 2 years now. Def agree with the appetite blunting effects with the caveat that there’s an adjustment period lol.

Bryan Pacheco : Intermittent fasting is simply a tool, not a diet. Skip breakfast and start your day of eating at about 12, 1, even 2. This will help you managing your calories when cutting.

William Chau : Who is your editor? Because honestly, aside from all of the useful information that can be gained from these videos ; the editing makes that much easier to consume all of this information. Edit : I just read the description ; Rashaun you are the man!

Orridge Poats : I'm surprised that you skipped over autophagy, which is a big part of why people take on fasting who have done their research.

Skabumble : I think we need Broscience Jeff in every video from now on

Samantha Grace : Lmfao i love your little Q&A part with the “bro version” of yourself 😂

bryce e : *I tried it*  I was a huge skeptic of fasting.. until I tried it. Wow does it work.. I feel healthier and more alert, as well as leaner. Try it for a week to see if it is for you. You won't be disappointed.

Patrick Bateman : To me personally, still eating all day im struggling to eat above my tdee 😂

Justin Evans : This is because 1000s of years of fasting has shown to improve life and life span. Look at the Native Americans for example. They got up, hunted and had a big feast at the end of the day all while being fasted. Whether we like it or not, we are programmed to fast. We lose fat and get more muscular this way because that is what our body is designed to do.

Lucas Guimaraes : Ma boy Neanderthal fasted all day long and was A BEAST, even beat those Mammoths sometimes

iVince905 : Correction @ 0:04 Intermittent Fasting is not a diet... its a way of eating.

Jay McLaughlin : I’m a huge fan of intermittent fasting. I’ve tried all kinds of eating plans, but fasting is the only thing that’s given noticeable results in a way that is easily maintained. Having made fasting part of my lifestyle, I don’t actually follow any strict plan now. I eat 1-2 meals, late in the day. Workouts are typically first thing in the morning after a black coffee. I managed to lose around 16kg in 8 months and around 11% bodyfat whilst increasing strength. Like in your video, the weight loss has slowed more recently, but that will always happen as you get more lean. For me, fasting is easy and makes losing or even just maintaining my weight much more enjoyable. It’s also much better for fitting into my daily schedule

issy909 : Love the Gym bro Jeff vs Science Jeff 😂😂 more of that pls.

Jimmy Jerk : You forgot to mention the "Godfather" of intermittent fasting, Brad Pilon. He was the first major proponent of IF with backed research in his book Eat Stop Eat. Later came Rusty Moore, Leangains, and Kinobody with a practical approach to IF. These guys were the first to create the craze.

Islam Abuauf : The dedication of Dwight @ 1:22 Killing it with the Science explained series, Jeff! Would love to see more of "Bro Jeff" though 🐻

Don Milliken : That's not Martin Berkhan in the video. It's Andreaz Engstrom, one of his clients.

Seth Dunn : My views and experience with IF. Out of the gate, I am a firm believer in Overall Calories in your day is what matters most, not when you eat them. I started IF (LeanGains Protocol) in Aug. 2013, been doing it since for prolly 95% of the time. There are times when I may eat first thing in the morning. After having started on IF, my health markers did improve. I had a physical done Aug 2013, and my BP was almost at the point where the doctor was talking about putting me on meds. This rather pissed me off, since I am someone who I thought was pretty healthy. I tried to eat right, I worked out, I don't drink, don't smoke and do not do drugs. So of course that got a huge laugh out of my friends and family to hear the news. So I started reading a lot of material. Got my diet adjusted, and started IF. By December of 2013 I had another checkup and my BP had dropped down to I think 123 over 73.....then another checkup in Feb. or March of 2014 had my BP down to 113 over 70 and a heart rate of around 53bpm I was able to get very lean, my workouts in the gym were very good, I felt more focused in the gym as well as in the morning I am a fairly lean individual to begin with, doing IF definitely helped to get to the next level. Now as far as bulking with my body type....I will say IF I think does have drawbacks here. I just am not able to maintain an appetite long enough to get in the calories I need daily. I can go about 3-4 days with a huge appetite, then after that, it will just crash, so any amt of weight (water weight) I put on during that time, just gets burned off.... But overall I at my age, I am satisfied with IF and how it works for me and my body type. I can better see how what I eat affects how I respond.

sillycod247 : When are you doing your debate with vegan gainz?

Tao Physique : Intermittent fasting is the bees knees. It makes staying fit seem easier and has some other interesting benefits, like increased creativity, productivity and mental sharpness during the fast. But I have to admit, although I center my channel around it, fasting is not for everybody and is not a magic solution to everything like some people will try to make you believe. It's just a great tool for diet adherence.

Khalil Aidani : [Laughs in Muslim]

HOTLILPAPI : Maaan I wanna just eat food I wanna live my life..

Alex Rodriguez : Been doing if for 7 years. Usually 6 hour eating window but i’ve done as little as 2 hour eatig windows. I’ll never go back. I can workout harder when my stomach isnt busy metabolizing. Theres a shit ton of more studies that show other positive benefits including an increase in hgh production and even increased recovery processes in boyh the muscles and even dna!

Pinnacle Of Man TM : I aspire to edit like you one day man. Love to know what program & techniques you use (maybe in a vid) :-) FASTING is the BEES KNEES BTW!

Dennis Jordan : I have been doing I.F. for about 4 months now, and started a workout program with it. the first two months I dropped almost 40 lbs and was gaining muscle and strength, the past 2 months I have been holding steady at 170 lbs but my body recomposition has been crazy, gaining size in my arms, legs, back and chest, and I have lost enough fat to be able to see my abs now. Going to start increasing the calories I take in a little bit after the end of this month to try a lean bulk and see if I can continue my gains. I know a lot of it is beginner/returner gains, but working out fasted def gives me noticeable strength and endurance gains over working out in the evenings.

Jerome Stockton : Perhaps do science behind prison inmates and levels of muscle mass?

tecnolover2642 : "In my opinion IF doesnt show much merit over standard caloric restriction diets...". Lol. Well in my opinion you are an idiot who needs to do more research on IF. IF totally destroys the standard caloric restriction diets! Clue. Three words. Basil Metabolic Rate. Now go read more.

Mohammed A : Me during Ramadan, great video Jeff 👌 still waiting for a full body training plan from you

Malik Richardson : I was 242.5 lbs (40.8% BF) on 5/29/17, I just weighed myself and I'm 216 lbs!!! I was morbidly obese because I loved eating, now with the aid of intermitteed fasting my relationship with food has changed and I've been losing about a pound a week!


Faxnummer : Jeff! The video of the guy doing dumbell press is not Martin berkhan!!

CanadianBad1 : This is the first video from you that missed the mark. Read some of the science advocated by people like Rhonda Patrick

Chris : so you're saying 4x20 is more anabolic? suuuh dude

thehiatusprt : Meanwhile, I’m on my 10th meal of the day with a protein ultra isolate ultra quick absorbing shake btw meals.

BosnishMaffia : Jeff, this editing is next level, keep it up dude!

JuliusCaesar : The only good effect of IF is blunting hunger and the restriction of calories. Which is why I highly recommend it to people who are on a cut.

Jonathan Feigert : I started intermittent fasting about 5 months ago. Can't say I've noticed any change in my ability to gain muscle or lose fat, but I definitely find that it blunts your appetite on the mornings and is overall more satisfying at the end of the day.

Alen GO : Why are you always just talking about anabolic signalling as opposed to health in general? As if having maximum anabolism aKa maximum muscle mass is the pinnacle of health. Guess what, 99% of people advocating fasting advocate it for HEALTH reasons (longevity, inflammation, gut health, lower blood glucose, REDUCED anabolic signaling, AMPK, decrease mTOR, IGF etc.), not gaining maximum amount of muscle mass. You're no better than Lyle McDonald and Alan Aragon...nothing matters and nothing is important EXCEPT DEM GAINS AND DEM MACROS BRAH. Ridiculous.

Intelligent Investor : IF is just another tool in the bag to achieve my goals. Usually I just skip breakfast if I'm not hungry

marcos l : What if you run intermittent fasting while also counting your macros wouldn't that be best of both worlds?

Filip Simon : I am a teenager that was doing 16/8 fasts it wasnt hard for me and i feelt better can someone tell me is it smart or am i torchering my bodey?

Live Till I Die : Intermittent fasting is just another way of getting a lower calorie intake. If it works for you then great but if you ate the same calories I'll bet you'll see the same results.

Sindre Nygård : Great video, as always! Just wanted to point out that the video didn't show Martin Berkhan, but rather one of his clients.

Radu Antoniu : Great video Jeff! But that's not Martin training, it's one of his clients.

Peter Traulsen : Hey Jeff, awesome video! Have you looked into the science about the HGH level increase due to intermittent fasting? According to a variety of studies the HGH level should increase as much as 800%. Please respond to this, as I'm working on a study concerning this. Thank you!