The Dark Side of Fasting (and Intermittent Fasting): Dr. Berg Explains

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Is fasting dangerous? It can be. Check out the dangers of fasting and how to avoid them.


Baby Food Alternatives:

How to Break Your Fast:

Refeeding Syndrome:

0:00 Introduction: Is fasting dangerous?
0:10 Benefits of fasting
0:16 Fasting explained
1:15 Dangers of prolonged fasting
13:58 Learn more about how to do intermittent fasting!

Today, let’s talk about the benefits and dangers of fasting.

Some of the top benefits of fasting include weight loss, cognitive improvements, and enhanced heart function.

Most of the dangers of fasting I’m going to cover aren’t related to a 16 to 18-hour fast. This applies more to prolonged fasting, which is when a person fasts for 48 to 72 hours—or even longer.

The purpose of eating is not just to get fuel. It’s also to get nutrients. When you’re fasting, you’re restricting nutrients. If your diet isn’t providing you with the nutrients you need when you do eat, you could end up with deficiencies that lead to certain issues.

It’s crucial to do a prolonged fast correctly and avoid common mistakes related to the dark side of fasting.

The dark side of prolonged fasting:
1. Refeeding syndrome
When you come off of a fast, have a small amount of food, wait a couple of hours, and have a little bit more. Avoid overeating or eating carbs.

2. Dirty keto
Make sure you consume nutrient-dense, high-quality foods on the keto diet.

3. Not taking nutrients while fasting
At the bare minimum, you need to take electrolytes, sea salt, trace minerals, and B vitamins while fasting.

4. Kidney stones
Avoid high-oxalate foods if you’re prone to kidney stones. Also, consume at least two and a half liters of fluid a day, and add lemon juice to your water. When you’re back to having meals, consume large salads.

5. Anorexia
Anorexia will cause nutritional deficiencies. Instead of fasting, get on the keto diet.

6. Athletes that have not adapted to fat yet
Give your body enough time to become fully fat-adapted before attempting prolonged fasting.

7. Fasting for children
Fasting isn’t a good idea for children. Eating three meals a day and cutting out snacking may be beneficial for children. Teenagers who are overweight may consider two meals a day without snacking.

8. Not getting enough nutrition while pregnant or lactating
Not getting enough nutrients while pregnant or lactating can lead to issues for the mother and child. Choosing a whole-food, natural prenatal vitamin over a synthetic prenatal vitamin is also important.

9. Muscle loss
If you’re older and noticing muscle loss, try adding a blend of amino acids to your diet.

10. Ketoacidosis
This rare condition occurs in people under very specific circumstances and isn't something most people should be concerned about.

Dr. Eric Berg DC Bio:
Dr. Berg, age 58, is a chiropractor who specializes in Healthy Ketosis and intermittent fasting. He is the author of the best-selling book The Healthy Keto Plan, and is the Director of Dr. Berg Nutritionals®. He no longer practices, but focuses on health education through social media.

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Dr. Eric Berg received his Doctor of Chiropractic degree from Palmer College of Chiropractic in 1988. His use of “doctor” or “Dr.” in relation to himself solely refers to that degree. Dr. Berg is a licensed chiropractor in Virginia, California, and Louisiana, but he no longer practices chiropractic in any state and does not see patients so he can focus on educating people as a full-time activity, yet he maintains an active license. This video is for general informational purposes only. It should not be used to self-diagnose and it is not a substitute for a medical exam, cure, treatment, diagnosis, prescription, or recommendation. It does not create a doctor-patient relationship between Dr. Berg and you. You should not make any change in your health regimen or diet before first consulting a physician and obtaining a medical exam, diagnosis, and recommendation. Always seek the advice of a physician or other qualified health provider with any questions you may have regarding a medical condition.

#keto #ketodiet #weightloss #ketolifestyle

Thanks for watching! Avoid the dangers of fasting by following these tips. I’ll see you in the next video.

39 responses to “The Dark Side of Fasting (and Intermittent Fasting): Dr. Berg Explains”

  1. I love your videos! You are truly helping people. The content on your channel is giving people the information they need to take back control of their health. Thank you for using your knowledge for the good of others. God bless you!

  2. Dr. Berg, thank you so much for sharing your knowledge and wisdom, it is very much appreciated ❤ I am binge-feeding off of all your videos.

  3. After I watched your videos and started healthy Keto + IF I lost more than 60 lbs this year! Around 10 lbs a month! Thank you ❤

  4. This is incredibly informative. And now that the genie is out of the bottle, tell me about the pancreas and how we destroyed that with our previous high carb diet and how to fix it!

    Thank you! Always!

  5. 91 hours as for now without food – 27% of my plan. I do it every year. Not always 14 days. This time I feel the difference. Besides nutrient dense food during my preparation I have increased the amount of cod liver oil in my diet, spiruline, berberine, extra electrolytes. Usually the 3rd-4th day I had a crash but now it’s different. I feel amazing. I doing a bit of sea salt and electrolytes but that spiruline, berberine and cod liver oil gave me something extra

  6. I just tried cutting carbs to less than 50g per day. I couldn’t sleep at all by the 3rd night. I used to have no problem fasting when younger. Dr Mindy Pelz talks about only fasting during high estrogen at the beginning of your monthly cycle but not after ovulation during high progesterone at the end. So many health suggestions seemed to get reversed after a couple of years for women. Turns out we are not men and often need to do the opposite. I was at my healthiest when doing a diet called Creating Wellness by Patrick Gentempo DC. It had 3 meals and 2 snacks and counted portions of protein, carbs, and fat. I think we just have to admit that we are all different and you have to do what works for you. I’m glad you are sharing more on genetic testing! I think that will help explain why certain things work better.

    • I just turned 50 and had tried intermittent fasting for months and couldn’t lose weight. Frustrated, I went to a nutritionist and she said IF doesn’t work for alot of people, especially middle age and older women.

    • I like her and follow her also but I have fasted for 7, 14 and 30 days and the position of my cycle never is a factor. I say do what works for u.

  7. I’ve been IF for 18 months and so far 40 lb loss without adverse effects. I see a Nutritionist for checkups every 6 months. Importantly, I follow Dr. Berg.

  8. Thank you Dr. Berg for such clarity and in-depth explanation. Your expertise is exceptional. As with any health improvement effect there is always a possibility of difficulties because nature is about a fine balance not extremes.

  9. Simple daily 16 to 18 hours fasting even does the wonder. I have been on 18 hours fasting for one and half years and these are my results:
    1. fat loss 126kg to 72kg
    2. high testosterone level from 239 to 598
    3. All clothes are loose and i have to give to obese people 😀
    4. waist 52 inches to 32 inches
    5. energy levels are always up
    6. Appreciation from people and high motivation level.
    who cares for 4 6 days fasting when you are getting all health benefits from 16 or 18 hours.

    • Bc after u have been doing that for a while the body gets adapted and u move to 48-72 hours or more to get benefits

    • Been on keto and IT since 2021, I only do 16- 18 hrs .. and I just recently started OMAD once a week..

      My sleep was affected badly, but I take magnesium at bedtime & almond milk and honey to counter insomnia

  10. I’ve been fasting for ~5 years out of the last 7 years, been known to get pretty extreme with it, but I noticed it’s a fine line you have to walk between fasting and an eating disorder

  11. Just finished a 16 day fast without incident following all these tips, greatly improved my conditions. Took 5 years to work up to that though.

  12. 17 to 24 hour fast is very easy never had any problems. I’m just getting into fasting longer. What I have noticed so far is if I’m not starting out with a keto lifestyle longer fasting has problems. I love fasting. After day two is when I feel the benefits and it’s easier to go longer each time. I stopped eating ALL sugars and glucose products back in January. The difference is great. I don’t miss them. I cheated a few times and felt sick afterwards. I don’t enjoy those products anymore.

  13. My wife nearly died from ketoacidosis this summer. Initially, doctors suspected it might be a manifestation of type 1 diabetes, but it turned out not to be the case. They asked her : ‘Are you following a keto diet?’ ‘No, but my husband is, and I tend to eat similarly to him.’ Given that she was lactating at the time, it appears that there is now documentation suggesting that a combination of keto and lactation can potentially lead to ketoacidosis.

  14. I fast every day but only between 13-15 hours. I’ve never felt better . I don’t do prolonged fasting. Thx Dr Berg 😊

  15. Great videos as always and thank you for sharing! Part of the problem with IF is that, like most diets, they are not studied on women as well as they are on men. And what works well for men doesn’t necessarily work well for women. We evolved to be frequent snackers, we did not evolve for long term frequent fasting. It doesn’t match what is needed for our hormones and can induce a lot of cortisol and stress. It also accelerates loss of lean muscle, which increases the risk for osteoporosis. And it also increases the risk of gallstones, which I’m going through now trying IF for over a year. Our blood sugar levels have to be stable in order to produce the right hormones for fertility, pregnancy and also post partum. Also we need adequate insulin levels for adequate thyroid hormone production. And for those with adrenal fatigue, this is absolutely the wrong diet for them in the majority of cases. I tell women in my clinic instead to do carb cycling. Eat a lot of fat and protein in the morning, with very little carbs. In the afternoon, a lot of vegetables and some fat. In the evening, complex carbohydrates and protein. On alternate days, eat more protein and fat and less carbohydrates. I know so many people are married to keto, but honestly I think its kind of a limiting belief that it is the only diet that works. There is a world of difference b/w carbohydrates from quinoa or black beans and carbohydrates from refined flour and sugars. I’m not a huge proponent of keto unless there is a specific need for it for which they may benefit, such as metabolic syndrome, pre-diabetes, type II diabetes, estrogen dominance or PCOS and are overweight. The exception is the lean type PCOS, they need to eat 5-6 small meals throughout the day. Otherwise, this manner of eating isn’t really beneficial.

  16. I’ve found that long term intermittent fasting has led to a very significant decrease in overall appetite. I recently found that I easily skip meals and I am not bothered by hunger to a greater degree. This means I now have to be quite mindful that I DO make sure I am getting the nutrients I need. Being diligent and mindful is the best tool in my case, and likely many others.

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