Does Fasting DESTROY Your Muscle Mass or Strength? | Dr. Jason Fung

Dr. Jason Fung is a physician, researcher, New York Times bestselling author and currently practices as a nephrologist (kidney specialist).

He is the co-founder of The Fasting Method, which provides the education, tools and community needed to successfully implement intermittent fasting.

Jason recently released The Diabetes Code Journal: The Official Workbook for Reversing Type 2 Diabetes Through Healthy Eating and Fasting.

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Jesse Chappus has in-depth conversations with health and wellness leaders from around the world. Topics include lifestyle, nutrition, fitness, self-help, sleep, meditation, spirituality and so much more. Tune in weekly to take your health to the next level!

[JesseChappus]

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[LTPottenger]

Fasting generally increases lean body mass, especially in your organs, which whither in time by aging and also from extended dieting. Some benefits of doing occasional extended fasting: High blood pressure is lowered to normal levels very quickly while fasting. Fibrosis/scarring is reversed over time, including in the heart and lungs.

Fasting increases T cell production and regenerates the thymus. T cells are vital in fighting cancer, autoimmune disease and infections but as we age the thymus stops making as many of them. Fasting releases stem cells, which then can become new T cells. Fasting also releases growth hormone, which regenerates the thymus itself, which aids this process!

Fasting stimulates phagocytosis, the ingestion of bacteria, plaques and viruses by the immune system. This will also remove any spikes, whether natural or unnatural in origin!

Blood clotting is reduced and blood clots and arterial plaque are reabsorbed into the body.

Blood sugar and insulin are lowered when fasting, allowing white blood cells to move more freely throughout the body and do their job.

Vitamin D plasma levels are increased as fasting improves metabolic health, and vitamin D in turn increases autophagy.

Fasting restores your circadian rhythm to normal over time.

Reflexes and short term memory are increased.

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

Telomeres are lengthened and fasting also increases anti-aging Yamanaka factors.

After 72 hours or more fasted, your body recycles up to 1/3 of all immune bodies, rejuvenating your entire immune system. This helps prevent the onset of new autoimmune conditions, which develop through a leaky gut and damaged immune system.

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

Thymus is regenerated, which suppresses aging and renews the immune system. The thymus also plays a vital role in fighting cancer.

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 extra tissue like loose skin while fasting, but the skinny or frail will have increased growth hormone release than the obese, which helps to make more lean tissue and reduce frailness.

When you move out of MTOR your body shuts down the building blocks of the cell required for viruses to replicate.

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

What breaks a fast? Anything with protein or carbohydrates in it will break a fast. Most teas and herbs are OK. Most supplements and meds will either break ketosis directly or contain a filler that will. Many meds are dangerous to take while fasting.

Does fasting lower testosterone? No, it raises it when the fast is broken by increasing lutenizing hormone. Fasting also increases insulin sensitivity, which helps with muscle building.

Fasts of 36-96 will not affect short term female fertility or affect menstrual cycle. They also may increase long term fertility, especially in women with PCOS.

Fasting reduces pain and anxiety by stimulating the endocannabinoid system in a similar way to CBD oil.

One day of fasting can cut your leptin levels in half and gets your immune system working properly again! This reduces leptin resistance, which impairs immune function.

Stomach acid is reduced over time while fasting and can allow for the healing of treatment resistant ulcers. Some patients may need continued acid reduction medication while fasting.

Does the body preferentially prefer glucose as a fuel? No. Except for brief periods of very intense exercise, your body mainly burns fats in the form of free fatty acids. Your brain also prefers to burn ketones at a rate of around 2.5 to 1 when they are available in equal quantity to glucose.

Fasting stimulates the AMPK complex and activates autophagy. Autophagy (literally self eating) will cause cells to recycle damaged proteins and foreign matter such as viruses. It will can kill cancerous and senescent cells

Lowering insulin via fasting virtually eliminates chronic inflammation in the body.

It increases mitochondrial function and repairs mitichondrial DNA, leading to improved ATP production and oxygen efficiency. Increased mitochondrial function also has the added benefit of increasing your metabolism, fighting infection and cancer prevention!

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

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

When you fast, this 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.

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

Exogenous ketones can aid with fasting, making it easier in healthy people and 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!

Glycine and trimethylglycine can also be useful supplements while fasting that won't break ketosis and have many benefits.

Children, pregnant or nursing women should not fast for periods longer than 16 hours. People with pancreatic tumors or certain forms of hypoglycemia generally cannot fast at all. Type 1 diabetics can also fast but it is more complicated and should be approached with caution as it could lead to ketoacidosis. If you experience extreme symptoms of some kind, especially dizziness or tremors, then simply break the fast and seek advice.

Resources:


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!

My community tab will always contain an updated version of this list of fasting benefits. I also have playlists on fasting and health topics.

[seanrothar]

My muscles are smaller on a ketogenic diet with intermittent fasting, but I am stronger. To add to what Dr Fung says here, not all of the excess mass in the carb eaters muscles is necessarily water. If they are lean, sure. But if not, some of it may be intramuscular/intermuscular fat.

I'm grateful to Dr Fung and Dr Robert Lusting for their work which has helped me immensely. I was in hypertensive crisis and obese with fatty liver disease, type 2 diabetes and pernicious anemia. All that remains is the anaemia, which I can live with. I need to stick to eating within a time-restricted window to keep the diabetes in remission, but after 6 months now, it's second nature.

My LDL cholesterol went up at first to 4.7, but it is now down to 2 (Canada/UK). (182 down to 77 (US)). This is despite a high saturated fat diet.

Keep up the great work Jesse. I really enjoy your videos.

[jamiecramer]

I am on day 2 of a fast and wanted to know the answer to this question, so thank you!

[trindakajans]

I ordered and impatiently awaiting Dr. Fung’s book ..I’m excited to receive it.

[blaze]

Excellent reasoned logic by Dr Fung !
This is what I strongly suspected - will keep fasting coupled with a Carnivore diet.

[Tom_The_GCT]

i implement a 60h fast every single week and eat the rest of my days at maintenance for a "cutting phase" and i gain strength and gain muscle.

[starwarsoele]

I did mostly omad the last 2 years, start training again after 15 year. But I had to eat more to get sufficient protein, now I use a eating window of about 8 hours and that works very well, i train in a fasted state, never had to little power. Also aded some carbs to my low carb diet. I am 55j and gaining good muscle and 100% naturally!

[fredwilliams]

I love how nobody's questions the facts that our bodies can repair broken bones deep lacerations and bad bruising with out high protien diets and yet we are told we must eat mass amounts of protein to repair micro tears which are less tramactic than the injuries listed above to repair muscle? Lol. Our bodies have a tremendous healing effect with out protein consumption!

[interuniversal]

Eating carnivore daily caused considerable muscle growth without additional exercise for me. If you don't eat enough meat either because you're fasting or eating carbs you will loose muscle mass.

[WE_ARE_LIGHT]

Fasting increases Growth Hormones. During extended periods of Fasting Testosterone decrease. But your testosterone levels go up higher than they were before the fast after you first meal to break your fast. To maintain strength and muscle mass during fasting you must work out with with a higher weight lower rep range. 6-10 reps. This will maintain muscle. One would have to go at least two days before you begin muscle atrophy. Consuming electrolytes during long periods of Fasting helps to maintain muscle mass also.

[starwarsoele]

Only whole food carbs, not to many. I also take creatine and tadalafil for good pump, and calorie surplus! Really works great. Greetz 👍✌️🤘

[peterbedford]

Longo has done a lot of research on this.

[roylereg]

This is a never ending controversy. But, true enough we would have not been born if our early ancestors would have been just blobs of fat after not being able to find food during tough seasons. But, listen to a body builder youtuber and they will claim the exact opposite.

[markj]

I am in a pickle with this one for a long time... Liver wants to produce protein and piece it up from amino acids 24 hours a day - from the muscle if no dietary source... Therefore the later breakfast the more disadvantage for the muscle fibers

[enverpeker]

ln long time water fasting if we make bodu building exercise, could we gain muscle? or

[trindakajans]

How do you know if you’re insulin resistant? ..and does fasting contribute to insulin resistance?

[anthonyhatton]

I did a 20x4 for 6months and even though I lost weight I could not build muscle I even lost muscle and I have worked out regularly for years and I did eat my protein, and even drank my creatine so it doesn’t work for everyone

[jkthelastsamurai]

Based on my experience fasting is fantastic for general health, but not so great for building mass, i fast 18 hours a day i don’t lose weight but i definitely lose size

[sercan]

saying growing muscle is independent of your nutrition is not true. if that was true nobody would lose strength on a cut. people who train properly, still put the same demand on muscle, they constantly break it down through training, if you dont supply enough nutrients, body cant rebuild damaged tissue. even if body didnt lose additional muscle with fasting ( which will also depend on duration of this fast, i dont believe a 3 day fast wont burn any muscle for example), by putting demand on muscle you are constantly beating it down. and hunger is also stress for body, so you will eventually start releasing cortisol. just like insulin is storage hormone, its anabolic to both fat and muscle cells, cortisol is catabolic to both fat and muscle cells too. if these fasts are also putting you to large caloric deficits, you are almost guaranteed to lose muscles. if you are just overcompensating when you eat, then obviously wont do a big net damage