How do you repair low metabolism after a low-calorie diet?
, medical content by Dr. Jason Fung, MD
in Intermittent fasting, Q&A 
How can you repair a low metabolism? Can you drink whey protein drinks when fasting? Is higher glucose levels normal on a strict carnivore diet? And, what is the difference between fasting and chronic undereating?
It’s time for this week’s Q&A about intermittent fasting and low carb with Dr. Jason Fung:
Repair metabolism
How do you repair a low metabolism after doing a very low-calorie diet? There must be a lot of people out there (like me) who have taken advice from the GP’s with their official dietary guidelines and lost weight using a low-calorie diet, and as a consequence, wrecked their metabolism and eventually regained the weight.
There is not a lot of information out there to help us. As this obesity epidemic continues and people turn to low-calorie diets in desperation, they too will be looking for help when it fails.
Belinda
This is certainly possible but can take some time. The key is to keep insulin low, and don’t reduce calories, which generally means following a low carbohydrate high fat diet. If calories are relatively high, and insulin low, then the body tends to use those ingested calories for energy and increases metabolic rate.
Dr. Jason Fung
Are whey protein drinks ok?
I typically drink a protein drink that is a whey protein. Is whey protein in protein drinks or bars not ok? Also, should I have apple cider vinegar during a fast? There is conflicting information as to whether it stops autophagy. And lastly, wouldn’t I have to avoid bone broth if I am want to reap the benefits of autophagy?
Thanks!
Maria
For autophagy, you should do a water-only fast. I generally advise people to avoid protein drinks and bars. Get your protein through natural foods.
Dr. Jason Fung
Is it normal to have higher glucose while on strict carnivore?
Is it a common occurrence for people’s bodies to have high glucose when on strict carnivore and OMAD intermittent fasting (22:2)?
Melissa
No, generally meat does not raise blood glucose. However, if insulin levels fall faster, then glucose may still remain high.
Dr. Jason Fung
Fasting vs. chronic undereating
Hi Dr. Fung,
I’ve recently finished reading The Complete Guide to Fasting1 (loved it BTW!) and at one point there was a seemingly throwaway line about a risk to those practicing regular fasting, and that is ‘chronic undereating’. Can you please unpack this a little bit? Because in my mum’s traditional view, only eating dinner (eg after a 24 hr fast) is chronic undereating, though you recommend (and indeed I enjoy) 3 x 36 hour fasts during a week and as far as caloric intake goes, those weeks are rather slim (as is much of the point of fasting).
My assumption is that not eating (i.e. fasting) is very different metabolically than eating, but not eating enough… am I right?
Shaye
Regular fasting is different from a chronic caloric restriction, such as, for example, a daily reduction of 500 calories per day, but still eating 3-6 times per day. Those are metabolically different because fasting allows insulin to drop and the body can then access its stores of food energy (calories) such as glycogen and body fat.
Dr. Jason Fung
Q&A videos
- MEMBERS ONLY
![Is low carb bad for exercise?]()
- MEMBERS ONLY
![Is low carb bad for the kidneys?]()
- MEMBERS ONLY
![Everything in moderation?]()
- MEMBERS ONLY
![Is low carb bad for the environment?]()
- MEMBERS ONLY
![Is low carb an extreme diet?]()
- MEMBERS ONLY
![Are there potential dangers with a low-carb diet?]()
![Women's questions introduction]()
- MEMBERS ONLY
![What is the main benefit of low carb?]()
- MEMBERS ONLY
![Does the brain need carbohydrates?]()
- MEMBERS ONLY
![Can low carb and keto help with PMS?]()
![Is low carb bad for gut bacteria?]()
- MEMBERS ONLY
![Why is low carb important to you?]()
- MEMBERS ONLY
![Can low carb make menopause easier?]()
- MEMBERS ONLY
![Is low carb bad for the thyroid?]()
- MEMBERS ONLY
![Is there a link between low carb and eating disorders?]()
- MEMBERS ONLY
![Can you get depressed on low carb?]()
![Is saturated fat bad?]()
- MEMBERS ONLY
![Can fasting be problematic for women?]()
Top Dr. Fung videos
![Diet Doctor Podcast #64 with Jason Fung]()
- MEMBERS ONLY
![Part 8 of Dr. Jason Fung's diabetes course]()
- MEMBERS ONLY
![The essential problem with type 2 diabetes]()
- MEMBERS ONLY
![Why low-fat diets don't work — Dr. Jason Fung's diabetes course]()
- MEMBERS ONLY
![The 2 big lies of type 2 diabetes]()
- MEMBERS ONLY
![The top 5 myths of fasting]()
![Part 7 of Dr. Jason Fung's diabetes course]()
![The 7 benefits of fasting]()
- MEMBERS ONLY
![The cause of obesity]()
- MEMBERS ONLY
![A new paradigm for type 2 diabetes]()
![What to do instead of counting calories]()
- MEMBERS ONLY
![Are all carbohydrates equally bad?]()
![Insulin toxicity — Dr. Jason Fung's diabetes course]()
![The top 5 tips to make fasting easier]()
- MEMBERS ONLY
![The most common questions]()
![The perfect treatment for diabetes and weight loss]()
![How to fast - the different options]()
![Breakfast! Is it really that important?]()
More
Intermittent fasting for beginners
More with Dr. Fung
Dr. Fung has his own blog at idmprogram.com. He is also active on Twitter.
Dr. Fung’s books The Obesity Code, The Complete Guide to Fasting and The Diabetes Code are available on Amazon.2
Diet Doctor will not benefit from your purchases. We do not show ads, use any affiliate links, sell products or take money from industry. Instead we’re funded by the people, via our optional membership. Learn more ↩
Diet Doctor will not benefit from your purchases. We do not show ads, use any affiliate links, sell products or take money from industry. Instead we’re funded by the people, via our optional membership. Learn more ↩
I am fearful of the keto approach also
Help!!!
Cecile
Will power. Being able to walk away from it. Even though your friends and relatives tell you, one won’t hurt you. Oh yes it will. Don’t let the enablers cause you to fall. Stay tuff
makes all the difference to me rather than saying I CANT HAVE IT ... my rebel streak
Ha ha
I’m also making mistake of eating too much protein as not losing weight, possibly too much cream and cheese as well ?? Not sure.. fat has loosened but still there !!
Love Keto food but may have to use a non nutritional sweetener for a once a month dessert. Haven’t had any over one month !
Have solved most problems such as making coconut bread, delicious coffee now in coffee machine by substituting milk for cream in canister is delicious!!
Should sell idea to coffee shops !!
The Obesity Code got me started !!
Dr. Fung will answer selected popular questions from here. Enter your question below, under “Ask”, and we’ll select questions for Dr. Fung.
https://www.dietdoctor.com/member/ask-the-experts/dr-jason-fung-new
It is a privilege to interact with you and the rest of the forum members.
I have got both your books, Complete Fast Guide Fasting and The Diabetes Code, but I got some questions:-
1. Have been diabetic for 24 years, DT2. Weighs 50.5 mgs, 5'.6 height. Got prescription pills, metformin (surkato). Initially I was given Glicazide but since last year in March I was introduced to low carb diet for 6 weeks, which was ok, Hb1ac 53 mml. However, after 6 months I was given metformin 1 x 2 since the hb1Ac was going up.
2. After being introduced to your theories am following it, but am losing more wait. I am pescatarian and mainly vegan. Eating lots of nuts, seeds and avocados including coconut oil and olive oils.
3. What would it be best approach for me to follow without losing further wait
- the blood sugar seem to respond well by eating two meals in a day or sometimes 3 meals.
- Could you please advice.
Many thanks,
Esther
You can get started with our free two week challenge. If you are on medicine for blood pressure or diabetes, please check in with your doctor to adjust your dosage as needed.
https://www.dietdoctor.com/low-carb/get-started
I'm a 58 year old menopausal woman, 20 kg loss would still see me above entering ideal suggested weight
I have been low carb/ keto OMAD for a couple of years but no weight loss or easy rebound of a small break.
Have gone strict KETO / OMAD since New Year and still no weight loss
I eat less than 10gms of carbs per day
coffee in the day with 2 tsp of cream
OMAD 5-6 days a week which is easy
Not hungry at all
Blood ketones have sat above 1.1 - 2.9 for 18 days pre meal
Went to the gym yesterday and able to do work out of weights and run without inducing above expected fatigue and no hunger trigger
Suggestions please
Here is our guide to OMAD. We generally don't recommend OMAD more than 2-3 days a week.
https://www.dietdoctor.com/intermittent-fasting/omad
This may help too - https://www.dietdoctor.com/how-to-lose-weight/menopause