The biggest concern most people have is that Intermittent Fasting will lead to lower energy, focus, and the “holy crap I am hungry” feeling during the fasting period and ruin them. People are concerned that they will spend all morning being miserable because they haven’t consumed any food, and thus will be miserable at work and ineffective at whatever task it is they are working on.

Intermittent fasting is a technique that involves restricting your food intake to a certain time window each day and then fasting for a specific period. There are several different fasting methods, with many variations that can fit nearly any personal preference or routine. A few of the most common types of intermittent fasting include alternate day fasting, 16/8 fasting and the 5:2 diet, each of which varies based on the amount of time you spend fasting during the week.
It can level up your brain, including positively counteracting conditions like Parkinson’s, Alzheimer’s, and dementia. As explained here in this TEDx talk by Mark Mattson, Professor at Johns Hopkins University and Chief of the Laboratory of Neurosciences at the National Institute on Aging fasting is grounded in serious research and more studies are coming out showing the benefits:
That’s what I suggest you do when you start fasting. It should happen naturally, and you shouldn’t have to force it. If you’re still a sugar burner instead of a fat burner, it’s going to be much harder…so if you’re serious about trying out this whole fasting thing, I suggest slowly transitioning to a high-fat low-carb diet. You can read about the benefits here.
This content is strictly the opinion of Dr. Josh Axe and is for informational and educational purposes only. It is not intended to provide medical advice or to take the place of medical advice or treatment from a personal physician. All readers/viewers of this content are advised to consult their doctors or qualified health professionals regarding specific health questions. Neither Dr. Axe nor the publisher of this content takes responsibility for possible health consequences of any person or persons reading or following the information in this educational content. All viewers of this content, especially those taking prescription or over-the-counter medications, should consult their physicians before beginning any nutrition, supplement or lifestyle program.

This content is strictly the opinion of Dr. Josh Axe and is for informational and educational purposes only. It is not intended to provide medical advice or to take the place of medical advice or treatment from a personal physician. All readers/viewers of this content are advised to consult their doctors or qualified health professionals regarding specific health questions. Neither Dr. Axe nor the publisher of this content takes responsibility for possible health consequences of any person or persons reading or following the information in this educational content. All viewers of this content, especially those taking prescription or over-the-counter medications, should consult their physicians before beginning any nutrition, supplement or lifestyle program.
Understanding the potential adverse effects of intermittent fasting is limited by an inadequate number of rigorous clinical trials. One 2015 review of preliminary clinical studies found that short-term intermittent fasting may produce minor adverse effects, such as continuous feelings of weakness and hunger, headaches, fainting, or dehydration.[29] Long-term, periodic fasting may cause eating disorders or malnutrition, with increased susceptibility to infectious diseases.[29]
The information you share, including that which might otherwise be Protected Health Information, to this site is by design open to the public and is not a private, secure service. You should think carefully before disclosing any personal information in any public forum. What you have written may be seen, disclosed to, or collected by third parties and may be used by others in ways we are unable to control or predict, including to contact you or otherwise be used for unauthorized or unlawful purposes. As with any public forum on any site, this information may also appear in third-party search engines like Google, MSN, Yahoo, etc. Your use of this site is governed by Harvard University and its affiliates Terms of Use located at www.health.harvard.edu/privacy-policy and may be amended from time to time.
Processed foods are usually packed with sugar additives and other undesirable ingredients that improve the taste but negatively affect your health. Even if "sugar" isn't listed on the label of ingredients, chances are it contains a substitute in some form. Whether it's sucrose, dextrose, high-fructose corn syrup or something similar, these ingredients can have the same (or worse) effects as sugar.
AN IMPORTANT CAVEAT: Intermittent Fasting can be more complex for people who have issues with blood sugar regulation, suffer from hypoglycemia, have diabetes, etc. If you fit into this category, check with your doctor or dietitian before adjusting your eating schedule. It also affects women differently (there’s a whole section dedicated to that below)

I am a 65-year-old male who started IF seven weeks ago. I only eat between noon and 8pm. I am obese, but losing about a pound a week so far. Notably, except for time, I have not changed what I eat at all. My diet was never terrible or great, and now it is the same, a mix of raw fruit sometimes and a donut another time. But I only eat it during the appointed hours. Remarkably, I do not feel hungry. I used to eat comfort breakfasts like pancakes or waffles, and I thought I would miss them. But no, I truly am not hungry in the mornings. I often delay lunch, but I still stop eating at 8. That alone probably has cut many calories of desserts. Bottom line: works for me so far.

I was very curious about this, so I asked the opinion of metabolic expert Dr. Deborah Wexler, Director of the Massachusetts General Hospital Diabetes Center and associate professor at Harvard Medical School. Here is what she told me. “There is evidence to suggest that the circadian rhythm fasting approach, where meals are restricted to an eight to 10-hour period of the daytime, is effective,” she confirmed, though generally she recommends that people “use an eating approach that works for them and is sustainable to them.”


So, if your goal is ketosis, intermittent fasting can help you get into ketosis even faster. Simultaneously, the keto diet makes intermittent fasting more doable because your body is already adapted to fasting with ketones. In addition, most people naturally eat less frequently on keto because of the high satiety level, so you’re likely already used to bigger windows without food.
I’ll share some of my experiences, now doing heavy strength training for 3 years in a fasted state: For my first “fasted” workout or two after starting an IF protocol, it was very weird to not eat before training. However, after a few sessions, I learned that my body could certainly function (and even thrive) during my training sessions despite not eating a pre-workout meal.
×