Fasting - Tips, Research and Myths

Fasting - Tips, Research and Myths

Intermittent Fasting: 5 Tips for Staying in a Fast

Fasting - Intermittent fasting has taken the dieting world by storm but in terms of its methods and practice as a whole, Intermittent fasting has been used traditionally for centuries around religious practices and culture. Further research into Intermittent fasting has established some interesting results and findings on the grounds of:

  • Promotion of Autophagy [1]
  • Benefits on the gut microbiome balance [2]
  • Reduction of oxidative stress [3]
  • Improving cognition [4]
  • Anti-aging aspects
  • Anti-inflammatory benefits [5]

    So, If you are wanting to get the most out of your new fasting lifestyle and are unsure of the grey realm of “What will break a fast or promote a better fast?” then below are our top 5 insights and tips to help keep you in the zone and get the most out of an intermittent fasting lifestyle.

    Glucose Metabolism and Insulin Sensitivity

    Insulin resistance is on the list of major health concerns.  This may stem from the correlation of less physical activity over the past few decades, combining the more sedentary lifestyle with high food intakes, in particular preference for more moreish foods like sugars/carbohydrates, salts, and fats over a diet higher in protein and moderate in carbohydrates. This conflicts with our own genome which was developed initially on a more paleo, hunter-gatherer lifestyle and was physically more active and also went through stages of fasting and feasting as well as less access to the carbohydrate dominant era we are seeing now.

    In the study, we see here [6] a small study conducted on 8 healthy men was placed on a mimic of a type of fasting lifestyle where every second day, they remained fasted for 20 hours and this was carried across a span of 15 days. Plasma free fatty acids were taken and measured before and after intervention periods to confirm they were indeed in a fasted state and from there the following conclusions where drawn:

    • Whole-body glucose uptake rates where increased indicating insulin sensitivity had increased.
      • Plasma adiponectin levels increased wherein obese individuals and insulin-resistant patients tend to be on the lower end.

      This was the first small scale but effective experiment to be conducted on humans that showed a visible increase in insulin-mediated glucose uptake rate induced by prior fasting periods and may show a promising outcome as a method for insulin-resistant disorders.

      So, how long is it ideal to fast for increased insulin sensitivity? On average 8 hours of fasting shows positive results on insulin sensitivity in test subjects [7].

      What Breaks a Fast?

      This is where the area of Fasting and Ketosis is blurred often. If you are fasting for the purpose of ketosis, then small amounts of carbohydrates, higher fats, and moderate protein foods won’t throw you out of Ketosis… but will interrupt the fast.

      So, if you are fasting for the purpose of getting into ketosis, your allowance or intake of these macros outside of high fats –

      • No more than 50g of Carbohydrates in a 24-hour window.
      • No more than 80g of protein as this can affect genuine ketosis again within a 24-hour window.

        Fasting for gut rest and metabolic resets – you are in most cases limited to black coffee, water, and moderate intake of short-chain fatty acids. Ie. MCT and often, MCT’s can be converted over to ketones. Around 1tsp. during a fasted state.

        As a general rule of thumb that is often listed by many people who live this lifestyle that you want to stick to less than 50 cal while in a fasting period of time; so, there is where drinks become your best friend in most cases. Teas, black coffee, water, bone broths in moderation as protein still contribute a calorific value as does fat which is present in the broth if brewed correctly. If you have a little bit of sweet craving you can add a zero-calorie sweetener like stevia to a cup of tea or black coffee.

        Set your Intentions – Why are you Fasting?

        Setting an intention around why you may be wanting to do intermittent fasting helps to keep you focused and on track, it's often a case of the mind when you are in the thick of a fast. Be kind to yourself, fasting is not designed to be a form of punishment or “I have to” it should be based around an “I want to” intention so that you are doing it for you and more likely to follow it if tied to goal.

        When you break your fast; say you have done the 14-16 hours of fasting and you now have a window of 8 hours, have a look at the foods you are putting in, are they nourishing sources of foods packed with good things or are you binging on junk because you think the fast offsets the bad food? If you’re doing the latter, you have got the wrong idea around fasting and may not feel the beneficial effects and metabolic outcomes desired and seen in studies.

        Fasting - Where is your Headspace and How is Your Environment?

        What are you surrounding yourself with? Supportive people or people who are likely to push up against your plans or pressure you against the desired goal? Are you exposed to a stressful or calm environment; we can’t always control the variables but we can control what we can control right? Here are some great ways to set your headspace up for fasting:

        • Blog or journal it -  it’s a great reflection tool when you get into the hang of fasting and can look back on your progress.
          • Meditate – while you are fasting or potentially thinking about your first meal, focus this energy on setting up some time to meditate – headspace is a great app for this!
          • Read – zoning out of the world and away from media and in particular those advertisements for the moreish foods we love most is a great way to take the pressure off and get mind-over-matter nailed on that one.
            • Do your grocery shopping in your eating window and stick to the outside aisles, these are the fresh foods and perishables. The lesser the number of ingredients on the label the less process it's gone through to be that food, always remember that!

              Can you Train while Fasted?

              What does the research say on training while fasted? Well, studies have been conducted on Fed vs Fasted training and this is around the standard 8-10hr fast of night time up to a period of 36 hours of fasting vs that of immediate feed, 30-minute feed and hourly monitoring from time of glucose intake to training and interestingly but not surprisingly the results carry some good weight.

              Fasted Training – Showed to be efficient in an aerobic state for an increase in the following aspects:

              • How you personally feel implementing a fasted lifestyle and if this affects your performance
                • Growth hormone stimulation.
                • Insulin sensitivity.
                  • Catecholamines were increased which are critical inductors for fasting lipolysis.

                    This indicated in a collective measure that fasted exercise does indeed improve Lipid utilization for the purpose of energy production [8].

                    However – fed exercise did show a better outcome than fasted when it was around anaerobic training methods increasing time to exhaustion in comparison with that conducted during a fast. Some of the participants of this particular study [8] 54% to be precise found they felt better having fed prior to aerobic and anaerobic training while the rest noted they felt no difference.

                    With this in mind – the type of fuel that was consumed in the fed state did impact results too, this study as mentioned above [8] indicated that glucose/carbohydrates deemed far superior to that of say a higher fat feed which actually inhibited growth hormone by increasing Somatostatin. The timing of the feed did also indicate a variable on performance as to if this was immediate or after a few hours in which it would be utilizing glycogen stores for efficacy.

                    Take-Home Message

                    There are many variables to take into account, this depends on:

                    • Goals in mind.
                    • How you personally feel implementing a fasted lifestyle and if this affects your performance.
                    • Compatibility with your current lifestyle and any underlying health conditions that may hinder outcomes.

                      Regardless, research is growing in the studies of physical and mental performance, metabolism, and endocrine function for fasting and incorporation of it in lifestyle. We will keep up to date on the literature as it comes out.

                      Have questions or want to see more content covered? Send us an email and be sure to follow us on socials @atpscience and so you don’t miss out on the latest from our team!


                      1. Nutrient-sensing nuclear receptors coordinate autophagy. Lee JM, Wagner M, Xiao R, Kim KH, Feng D, Lazar MA, Moore DD Nature. 2014 Dec 4; 516(7529):112-5.

                      2. Gut microbiota from twins discordant for obesity modulate metabolism in mice. Ridaura VK, Faith JJ, Rey FE, Et AL. l. Science. 2013 Sep 6; 341(6150):1241214.

                      3. Caloric restriction and intermittent fasting: two potential diets for successful brain aging.Martin B, Mattson MP, Maudsley S Ageing Res Rev. 2006 Aug; 5(3):332-53

                      4. Caloric restriction and intermittent fasting: two potential diets for successful brain aging. Martin B, Mattson MP, Maudsley S Ageing Res Rev. 2006 Aug; 5(3):332-53

                      5. Alternate day calorie restriction improves clinical findings and reduces markers of oxidative stress and inflammation in overweight adults with moderate asthma. Johnson JB, Summer W, Cutler RG, Et Al. Free Radic Biol Med. 2007 Mar 1; 42(5):665-74.

                      6. Effect of intermittent fasting and refeeding on insulin action in healthy men. Halberg N1, Henriksen MSöderhamn N,Et Al. J Appl Physiol (1985). 2005 Dec;99(6):2128-36. Epub 2005 Jul 28.

                      7. Early Time-Restricted Feeding Improves Insulin Sensitivity, Blood Pressure, and Oxidative Stress Even without Weight Loss in Men with Prediabetes. Elizabeth F.Sutton1RobbieBeyl1 cell metabolism Volume 27, Issue 6, 5 June 2018, Pages 1212-1221.e3

                      8. Effects of fasted vs fed-state exercise on performance and post-exercise metabolism: A systematic review and meta-analysis. T. P. Aird1 | R. W. Davies1 | B. P. Carson1,2. DOI: 10.1111/sms.13054

                      9. Comparison with ancestral diets suggests dense acellular carbohydrates promote an inflammatory microbiota, and may be the primary dietary cause of leptin resistance and obesity. Ian Spreadbury Diabetes Metab Syndr Obes. 2012; 5: 175–189. Published online 2012 Jul 6. doi: 10.2147/DMSO.S33473