As anyone in the nutrition field is aware, there are plenty of extreme dietary practices. Personally, I’ve heard about everything from the baby food diet to the Dukan diet to something about alkaline blood levels. Usually, these extreme dietary practices are met with an eye roll, knowing that these outrageous diets will last about as long as an avocado in it’s prime. But what if there was a dietary trend that promised long-term health benefits that focused not necessarily on what you eat, but when you eat?

Intermittent fasting is any period of voluntary food restriction. Protocols are varied and might include religious fasting, time restricted feeding (i.e. eating all calories within a short time window) or scheduled days of extreme caloric restriction (i.e. ≤ 25% of energy needs) followed by normal or high calorie days.

I am always skeptical of any diet or dietary pattern that claims to fix everything from obesity to cancer, but – bro-science aside – intermittent fasting is gaining a substantial amount of attention in research. A recent and thorough review in The Annual Review of Nutrition concluded that intermittent fasting might be a viable strategy to benefit overall human health, including improvements in biomarkers associated with chronic disease. Notably, however, most human research studies are limited by small sample sizes, lack of control groups, insufficient follow-up, and inclusion of normal weight or healthy individuals who are unlikely to respond to interventions.

The best diet for optimal health is one that is maintainable. A large (n=100) and long (1 year) study in metabolically healthy obese adults published last year found that drop-out was highest in the group randomized to alternate-day fasting. The long-term adherence to intermittent fasting and applicability to public health is therefore questionable.

Diet quantity and quality will always be paramount for the promotion of optimal health and healthy aging. For me, I couldn’t live without my morning matcha latte and eggs… but maybe breakfast isn’t the most important meal of the day, at least for habitual non-breakfast eaters.

17 replies
  1. Phodie
    Phodie says:

    Is there restrictions on what to eat in intermittent 6:18 kind of Diet do need to count calorie intake thanks

    • Sarah Purcell
      Sarah Purcell says:

      Hi Phodie. Intermittent fasting is just a method of eating food (or avoiding it however you want to look at it) within a certain time window. Inherently, it does not have any food restrictions per se. However, long-term energy balance (i.e. body weight) is dependent on energy in (the food you eat) and energy out (the calories you spend), which are influenced by things like appetite, environment, exercise, genetics, body composition.

  2. Mikaele
    Mikaele says:

    I’ve done intermittent fasting for about a year! And I would have to say it def keeps you in order cause it give you more of a plan! Once you get it down it will be just like brushing your teeth but be careful with the types of food you’re eating just like any other diet! But I like the fact I have constant energy and my body works like a fat burning machine! Went from 245lbs to 194lbs still a little too muscuclar but would like to lean down more! There’s so much to say about it!

    • Sarah Purcell
      Sarah Purcell says:

      It’s good to hear you’re feeling better and recognizing that diet and exercise are important with intermittent fasting, just like any other lifestyle. Of course, it;s not for everyone, but some people certainly prefer it. Keep up the good work!

  3. Tina Belcher
    Tina Belcher says:

    Best line of the day – ”Usually, these extreme dietary practices are met with an eye roll, knowing that these outrageous diets will last about as long as an avocado in it’s prime.”

    Thanks for the article.

  4. Don
    Don says:

    Hi Sarah,
    Good info! I’ve been doing IF for a little over a month. I jumped right in with a “5/19” protocol. But within the last few hours of the fast I have about 8-10 pistachios. I’ve worked off about 3 pounds to date. My weight has always been consistent and I have kept my athletic shape for years.
    I simply started IF to jumpstart my metabolism a bit. Amazing what aging does!!! Another aspect of IF that I like is I can do it on a daily basis…I go off IF on weekends.
    So far- so good! Now my question…am I doing wrong by having anything other than water or black coffee, when I eat the pistachios?!?
    Thank you for your time!

  5. yannick
    yannick says:

    I tried pretty much all diet, including fasting and ketogenic, one meal per day, and i can honestly tell you that if you fast too long, you will have the same side effects as the low carb diet, i suffered from hair loss, thinning, lack of energy, bing, and 2 months in, i started to feel very hungry…

    I stop doing those diets because they are plain stupid, limit one food group, don’t eat this eat that etc…. i got adrenal fatigue too doing keto and fasting and P90X3.

    The best way of eating is either the Mediterranean diet or the DASH diet, both diets include all food groups, and make sure you get all your nutrient, my hair as grown thicker, i have lots more energy, i eat breakfast, i eat meat, i get my iron, calcium magnesium and all the body needs. Yogourt, oats, milk, etc…

    I have been trying those diets since 1996, since i read body opus, the protein diet, the sugar addict diet, atkins, the ketogenic diet, ultimate diet 2.0, eat stop eat, 18/6, the warrior diet, always looking for quick fix to lose weight, but those fads will come with side effects.

  6. Jake
    Jake says:

    Like you, I also cannot live without my breakfast (for me, a nice piece of toast with nut butter). I’ve been reading a few articles about intermittent fasting and how great it is for weight loss. While I’m ready to give up my daily toast, I’m still skeptical about how a diet based on meal timing can actually work?

  7. Roderick S. Beck
    Roderick S. Beck says:

    The animal studies are overwhelming convincing and the same genes that modulate aging in the animal studies also modulate aging in human beings. The problem with the current author and medical profession in general is their extreme conservatism.


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