Is Fasting for Weight Loss Safe?

The reasons why fasting longer than 24 hours, and particularly three or more days, should only be done under the supervision of a health professional and preferably in a live-in clinic.

Next I turn my focus to intermittent fasting—stay tuned:

Thanks for watching. I hope you’ll join in the evidence-based nutrition revolution!
-Michael Greger, MD FACLM

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Image credit: Jean Fortunet / wikimedia

[NutritionFactsOrg]

The reasons why fasting longer than 24 hours, and particularly three or more days, should only be done under the supervision of a health professional and preferably in a live-in clinic.

[crazyfarmgirl]

What about intermittent fasting
That is something i have read is beneficial for longer life and slowed agubg

[courtneyhamilton]

This is great! However, I would really love videos on intermittent fasting (16 - 20 hours a day) for weight loss/health/cells etc vs long term fasts for days.

[jhadesdev]

This is how the Vegetable Police ended up in the hospital after breaking a 21 day fast with a raw egg LOL

[michaelrenzelman]

Not sure who's pushing exterme long-term fasting. Most are advocating at best 3-4 days not weeks or months.

[sweetlemmon]

I think the big problem is the refeeding process and not enough vitamins/minerals. I did a 5 day water fast- very weak, couldn't leave the bed, brain fog, and fainted on day 5. I then ate 2 fries leftover from my husband and threw it all up. I had to go to the hospital. A year later I tried again. 21-day water fast- vitamins, liquid minerals, and electrolyte drink. I felt euphoric, almost high even. It is hard to describe but I never felt that good in my life. I ended the fast with a small piece of watermelon, and continued to eat that for 2 days, then started adding in other soft fruits, soups etc. Lost 36lbs, acne cleared, my hair is shiny and thick and my bowels are now regular. I only gained 5 pounds and I did this fast 5 months ago.

[RabbitFoodFitness]

The information about using vitamins when fasting is very interesting. Thank you!

[vcp]

I did three cycles of the Fasting Mimicking program and found that if I didn't ease back into feeding my blood pressure went through the roof. I already have an issue with blood pressure, so this may not be a common side effect of eating too quickly after an average fast, but if did freak me out. I was not expecting it and thought I might need to go to the emergency room. Lesson learned. Cheers!

[jimmyovids]

What if I told you intermittent fasting was really intermittent eating?

[drmabdulrazzaq]

There is a significant difference between extreme fasting (starvation) and intermittent fasting.

[mattrichardson]

Thanks for this Doc. There’s nothing magical about fasting, and if there’s dangers, people really should be informed. If benefits can be attained with safer means- why would you take the risk?

[dfleischman]

I don’t think you should conflate deaths from fasting in ghettos, wars, and case studies of fasting deaths from decades ago before people understood electrolyte supplementation and modern day therapeutic fasting. More recent fasting studies have shown adverse events but rarely anything life threatening as you covered in this video. I would like to see fasting compared with gastric bypass for obese patients- I think fasting is likely safer and more effective. Also- a low calorie diet is great but many people find eating very low calorie to make them much hungrier than fasting- the latter is more effective. While I generally appreciate the balance of your videos, the first one was fairly positive, this one was pretty negative and purposefully scary.

[Shane-The-Pain]

This is the first NutritionalFacts vid that made me suspicious. Too many death threat-type case studies for my comfort.

Still love ya, NF. Just feel like the deep research is where I'll find better answers on fasting, intermittent or otherwise.

[rainguynw]

Has Dr. Greger supervised fasting patients? Dr. Jason Fung has, and continues to with minimal problems. Even in elderly patients. I'll stick with Fung on this one.

[tiamariza]

Thank you so very much for taking the time to do research and make these videos. It may take me hours to watch multiple short videos but I am sure that it takes you longer to gather this information.

[deepakhiranandani]

Thank you. Yes it's good to know these dangers in detail, like the thiamine.

[alenfishman]

so, ive been doing this thing where i fast 1 weekend a month for a couple days to help control my micro biome. its been helping because ive lost most of my cravings for junk food and have no problem eating whatever i should be eating. im a little confused based on what he said. in most of the studies they talk about 5+ days, but in one section specifically any fasts over 24 hours should be monitored. should i be concerned about fasting once a month? does anyone have an extra info on this?

[bobschmob]

Fantastic research and linear analysis.

[fireside]

I somewhat agree, but I think a 3 day fast is nothing to worry about either. I'm certainly not going to pay a doctor for something that simple. As usual, it has to do with overall health. Get exercise, eat healthy, and a fast won't be a problem. You can get a wrist bp checker and have a good idea of your overall health. Mine cost 20 dollars and talks. For weight loss, I think a one day fast per week, with a healthy diet has been the most effective for me. I didn't try a longer one, but I didn't need to either. That's the fastest I've ever lost weight.

[lyfecast]

Great information about vitamins and micronutrients! Too often overlooked.