If the words ‘intermittent fasting’ cause a state of panic for you, you’re not alone; ‘hangry’is a real condition!
So why on earth would anybody do it?
While fasting is something that has become very popular over the past few years, it is not something new- it’s been around forever. Ancestrally, humans haven’t exactly had food readily available; there was no supermarket down the road.
Before we delve into the intricacies, let’s be clear on a few things: Fasting is not the same as starvation– it is a voluntary restriction of food for a certain period of time. Many religious groups have been doing it for thousands of years.
Secondly, there is not a lot of research on humans and fasting- there is plenty of mice. So, as we progressively build our understanding of the health implication of intermittent fasting for humans, a plethora of varying opinions have arisen with not a ton of information available. Thus, there is flexibility in what I say and what others say, which will solidify with time, as we continue to learn more.
What we do know is that this pattern of eating can help with fat loss, lower your risk of disease and increase your lifespan. It has also been shown to have a positive effect on metabolism and metabolic health, making it a healthier way to lose weight than standard calorie restriction.
Sounds great, right? But what does fasting actually entail?
Intermittent fasting (IF) is a fast that generally spans 12 to 36 hours- there are a lot of methodologies! The most popular and the one I deem to be the simplest and most sustainable form of fasting is the 16/8 method. This is where you only eat for an eight-hour window (say 11 am to 7 pm) and fast for the remaining 16. This means that around half of your fasting is conducted while you are sleeping and you literally may just be skipping breakfast.
How can it serve you?
Normalising various fat burning hormones: Hormones strongly influence your appetite, how much you eat and how much fat you store and burn. Namely, insulin is the main hormone involved in fat metabolism- it tells your body to store fat and to stop breaking down fat. As highlighted in my previous post (Simplified Nutrition), normalising insulin sensitivity is the key to optimal health. This is because insulin resistance contributes to a wide range of chronic disease from diabetes to heart disease. In fact, this pattern of eating has been shown to reduce fasting insulin levels by 20-31%.
Increasing human growth hormone (HGH): Studies have shown that fasting promotes the release of HGH, which plays an important role in muscle growth and fat loss. When blood levels of HGH are increased, fat burning and muscle preservation are promoted.
Inflammation reduction: Studies have also shown reductions in inflammation markers whilst also reducing free radical damage in the body. This can have benefits against the development of many diseases.
Metabolism boost: Contrary to popular belief, fasting for short periods can actually increase your metabolism, not slow it down. This is thought to be related to the increase in the hormone norepinephrine, which promotes fat burning. The increase in norepinephrine helps preserve muscle mass as your body is able to utilise fat stores as energy instead of breaking down your muscle to make glucose (gluconeogenesis). The more muscle your body carries, the higher your metabolic rate.
Heart health & cholesterol: Studies have shown that intermittent fasting could reduce triglycerides and LDL cholesterol levels.
So, what does a fast look like?
DO: Drink water, black coffee or tea, maybe a little bone broth. Increase your sodium intake from good quality sea salt to minimise the effect of excess sodium loss.
DON’T: Force it! You don’t have to follow any particular protocol. Find out what works for you. Maybe a 16/8 window only works on certain days for you. Listen to your body. Experimenting with this could be the perfect opportunity for you to get in touch with what your body actually needs.
Most importantly- get your food right first!
This will only work if your body is fat adapted, ie, your body has the ability to use fat as fuel… otherwise your body will use your muscle to energise you throughout the fast via gluconeogenesis. Your body will be hunting for the glucose if you’re still a sugar burner. If you’re used to using fat as energy, then you’ll keep on doing that- your body will spare your muscle. Hugely important!!
DO NOT DO THIS ON A CALORIE RESTRICTED DIET!
Nice, hearty, nutrient dense, big meals! Vegetables, proteins, and fats. This is not the time to worry about calories. Eat to fill yourself up, feel really good and fuel the rest of the day. Keep salt intake high– add high quality sea salt to your water. If you’re eating good, real, whole food, there will be virtually no sodium.
What to expect:
Expect to Feel hungry. We’re used to feeling hunger, then eating. When you’re in a fasted state and you’re using fat as fuel, you’re still going to feel hunger, but your body knows to use fat as fuel- you already have the energy there in your fat stores.
PLEASE NOTE: there is a difference between feeling hungry & feeling HUNGRY! It’s totally normal to feel like you have an empty stomach and to have a little grumble which comes and goes. If you get to a point where you feel so hungry that you can’t focus on anything else, you’re having trouble concentrating, or have no energy, then please eat. It’s not worth it & it will be causing your body a significant amount of stress!
The hunger you should feel should be very minor. You should be able to go about your day with a bit of hunger that comes and goes in waves. When you’re starting out, this will typically be around when you usually have a meal. E.g. If you normally have breakfast at 8am, you may start to feel a few hunger pangs or a little grumble at about this time. Drink some water. Drink some electrolytes. It will pass.
You might have to go to the bathroom more frequently. This is just your body getting rid of things it doesn’t need as a consequence of the fasting.
A lot of people experience a euphoric or heightened level of energy at times. You may notice that your hunger subsides- it will become less and less and you may start to feel a little more mental clarity and focus. This is sometimes a direct result of simply not having to worry or stress about getting that ‘all important’ breakfast in amongst the rest of your busy schedule.
Fasting & working out:
Do what feels right! You may want to lower the intensity of your sessions while in a fasted state. Particularly if your fast is longer than ~18 hours. I would scale your training intensity back a notch while you experiment.
Find your sweet spot.
DO NOT push through a workout that is too intense for the amount of food you’re eating (or not eating) on that day. Please listen to your body & modify as you need to. Some people find they feel really great training in a fasted state, others find they do better feasted… there is no right or wrong!
Intermittent fasting is definitely one of those things where it may be great for one person and not so good for the next. If you aren’t into it that’s completely fine, just forget you ever read this post. It is definitely not something that needs to be done. In fact, some studies suggest that women may not benefit from fasting as much as men. If you are unsure, give it a go to see if it works for you.
However, I can’t stress enough that you should focus on the quality of your food before you consider fasting, as fasting combined with a highly processed or nutrient devoid diet is probably just going to make things worse.
As with everything nutrition related, there is no one-size-fits-all approach.
So, get into the habit of BACKING YOURSELF!
Your body is very clever at telling you what works best, you just have to listen!
References:
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Barnosky AR, Hoddy KK, Unterman TG, Varady KA. Intermittent fasting vs daily calorie restriction for type 2 diabetes prevention: a review of human findings. Translational Research. 2014;164(4):302-11.
Catenacci VA, Pan Z, Ostendorf D, et al. A randomized pilot study comparing zero-calorie alternate-day fasting to daily caloric restriction in adults with obesity. Obesity (Silver Spring, Md). 2016;24(9):1874-1883. doi:10.1002/oby.21581.
Hartman ML, Veldhuis JD, Johnson ML, Lee MM, Alberti KG, Samojlik E, et al. Augmented growth hormone (GH) secretory burst frequency and amplitude mediate enhanced GH secretion during a two-day fast in normal men. J Clin Endocrinol Metab. 1992;74(4):757-65.
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Heilbronn LK, Civitarese AE, Bogacka I, Smith SR, Hulver M, Ravussin E. Glucose tolerance and skeletal muscle gene expression in response to alternate day fasting. Obes Res. 2005;13(3):574-81.
Ho KY, Veldhuis JD, Johnson ML, Furlanetto R, Evans WS, Alberti KG, et al. Fasting enhances growth hormone secretion and amplifies the complex rhythms of growth hormone secretion in man. Journal of Clinical Investigation. 1988;81(4):968-75.
Patterson RE, Laughlin GA, Sears DD, et al. INTERMITTENT FASTING AND HUMAN METABOLIC HEALTH. Journal of the Academy of Nutrition and Dietetics. 2015;115(8):1203-1212. doi:10.1016/j.jand.2015.02.018.
Zauner C, Schneeweiss B, Kranz A, Madl C, Ratheiser K, Kramer L, et al. Resting energy expenditure in short-term starvation is increased as a result of an increase in serum norepinephrine. Am J Clin Nutr. 2000;71(6):1511-5.