Intermittent Fasting – Fast Without Getting Furious
Intermittent fasting – is it really effective for long-term weight loss and can you fast AND maintain a positive mood?
How long are you able or willing to go between one meal and the next?
If you’re not waking up for a night-time nibble then you’re probably already fasting for a 9 hour stretch without a second thought. If you eat dinner and finish snacking by 10pm, then eat breakfast at around 7.30am, that’s a full 9 1/2 hours without food. Yet, if you imagine yourself doing this during the day, the picture is completely different. Perhaps you’ve noticed how on some days you eat every 2 or 3 hours. You have breakfast, then get to work and make a tea or coffee, perhaps grabbing a biscuit or snack bar as well. Then there’s lunch. Followed by a tea and another biscuit or a chocolate a couple of hours later. Then you head home for dinner, before squeezing in a final snack. If this sounds familiar, it’s really not surprising that the idea of intermittent fasting seems like an impossible feat.
And is there really a point to trying to squeeze all your meals into a shorter period? Or will these longer periods without food leave you feeling ‘hangry’? You can fast, but feel a little bit furious.
In this article you can explore the idea of intermittent fasting and see whether it could suit you. What are the different ways of doing an intermittent fast? Does intermittent fasting lead to weight loss and how does it compare to lower calorie diets? Can everyone eat like this?
What Is Intermittent Fasting?
Fasting is an age old practice that occurs for many reasons. There is religious fasting, such as for Muslims during Ramadan, where for 30 days adults are called upon to abstain from eating or drinking anything from sunrise to sunset. Seventh Day Adventists also fast – primarily to avoid unnecessary excess. Their dietary patterns invlove eating 2 meals a day, with the second meal eaten in the mid afternoon. As a result, there is a long nightly fasting period, of 15 hours or more. Of course, fasting doesn’t always have to be linked to religion, it can also be practiced for health.
Intermittent fasting (IF) adds a time restriction. There are periods when you eat freely; and periods when you don’t eat at all. However, IF isn’t about gobbling down as much food in a short period of time so that you spend your day feeling uncomfortably stuffed. Nor is it about self-denial or having a will of iron. Instead, many people choose to eat this way to benefit their health. For instance to help them lose weight. Or to improve their metabolic health markers and manage pre-diabetes, diabetes or cardiovascular disease.
Is this effective? There’s more on this in a moment, but first take a look at the patterns of eating you can follow on an IF.
Types of Intermittent Fasting
There are actually several ways to do an IF, for example day by day or over a period of a week. Here’s what they look like.
Time-restricted eating. This is a fast which fits into a 24hour period where you eliminate eating in the nighttime or prolong the time you go without food through the night. Your fast will last for about 10 hours.
Overnight fasting. Another type of fast which fits into a 24hour timespan where you have a 12 hour window in which to eat and 12 hours to not consume. Your fast will last for 12 hours.
Whole day fasting. This type of 24hour fast is a more rigorous practice where you consume one meal every 24 hours. Your fast will last for around 23 hours.
Alternate day fasting. In this one day total fast you have one day on and one day off, so food is consumed every other day. Your fast will last for around 34 hours (evening +fast day + the next morning until you eat).
Intermittent energy restriction fasting. With this pattern of fasting you spend most of the time eating without restriction, then on selected days you reduce your calorie intake and eat enough food to meet around 20 – 25% of your energy needs. The 5: 2 diet is a popular example of this eating pattern. In all instances, when food and drinks are consumed, you can eat freely until you are full. You will fast for 2 days each week.
Choose your day fasting, what I call flexi-fasting. This is where you practice time-restricted eating a few times a week. It’s similar to the 5:2 diet pattern of eating where you pick a couple of fast days each week, but on those days you reduce your eating window to 8 hours (say between 12pm to 8pm.). Your fast will last for 2 days per week.
Is Intermittent Fasting OK For Everyone?
Is IF suitable for everyone or are there times when it doesn’t make sense?
Women who are pregnant, or trying to get pregnant, really shouldn’t fast. IF has an effect on your hormonal cycle and causes a process called cellular autophagy. We’ll talk more about this in a moment.
IF can also affect how your medication is absorbed and acts in your body, so if you have quite a long medication list then fasting might not be for you.
If you have type II diabetes then IF will only ever be done with the guidance of a healthcare professional. It’s not something that you should try to do on your own, as the fluctuations in your insulin and blood sugar levels can have concerning effects.
Finally, if you currently have or have had any disordered eating patterns, such as anorexia or bulimia, then it may be wise to consider the emotional toll of doing an IF.
Intermittent fasting is not ideal for everyone, and probably won’t be suitable if you are pregnant, on many medications, have type 2 diabetes or other metabolic condition, or have experienced an eating disorder.
Does Intermittent Fasting Help With Weight Loss?
This is a really common reason for IF – people hope that if they don’t eat any food at set periods of time, it will help them lose weight. After all, if you eat less on particular days, your total weekly food and energy intake should also decrease. But is this what happens, or are you likely to eat more at the next meal to make up the missing calories? In fact, how does IF compare to conventional dieting – where you simply reduce the number of calories you eat each day?
IF appears to have several health benefits, and weight loss is one of them.
For example, in a mouse model of modified alternate fasting, visceral fat decreased when energy was restricted . In this particular study, the mice alternated between eating freely on one day and eating 75-80% less on the next.
A recent review examined 9 studies where humans followed a modified fast, from between 2 to 6 months . In 7 of these studies, participants lost a significant amount of weight – from 3.2% in one of the longer studies to a whopping 8% in another 8-week trial.
It’s also really interesting when eating patterns are compared. Which is better – IF where you eat less by restricting your meal times, or a diet where you reduce your calorie intake by generally eating less each day?
Several reviews and meta analyses of the data have led to a somewhat surprising conclusion – they are pretty much the same.
IF does promote weight loss.
In addition, IF has a modest effect on blood lipids, inflammatory markers and markers of blood glucose regulation. (Disordered levels of blood glucose, insulin, and fats often accompany obesity and excess weight).
But on the whole, there is no difference in the amount of weight lost whether you choose to IF or cut back on the overall amount you eat. Likewise, the desirable changes to your metabolic markers caused by IF are similar to those achieved with simply eating less over time.
This is great information to have, especially if you’re health goals include making changes with overweight, obesity, pre-diabetes, elevated cholesterol, fatty liver or increased inflammation in mind.
If you are comfortable adjusting your diet so that you decrease your total energy intake, and can do this every day, then that’s great.
However, if you feel you would respond better to alternating between periods of zero intake and windows where you eat healthily, then IF would be a good choice.
Intermittent fasting does promote weight loss. It may also help lower levels of inflammation, regulate your blood lipids – cholesterol and triglycerides – and improve how you metabolise dietary carbohydrates. However, these results are variable and may be influenced by your starting body weight and measures.
Does It Matter WHAT You Eat?
One other thing to consider is what to eat on the days / periods that you don’t fast. Should you shove any old grub down your throat, or is it better to make a considered choice?
I’m 100% certain you know what I’m going to say here! That’s right, opt for a diet which is as whole, unprocessed, and natural as you can manage. When you have a smaller window to eat it doesn’t make sense to waste time eating foods that don’t provide the key vitamins, minerals, and healthy carbs, proteins and fats that your body needs.
Does It Matter WHEN You Eat?
One of the big questions about IF is what to do at breakfast. Is it OK to miss it out, or should you time your fast to end so that you can eat it when you wake? Another question that might have occurred to you is when is the ‘best’ time to eat? If you were doing a time-restricted-eating type of IF, where you had 8 hours to eat, would it be ok to eat, for example, between 2pm and 12pm?
Some of the data collected from mouse models suggest that it could be important to synchronise fasting with daily circadian rhythms. Obese mice do respond metabolically to IF. As Patterson & Sears summarised, when the time allowed for eating is restricted, and the fast lasts from between 12 to 21 hours, reductions in bodyweight, cholesterol levels, triglycerides, glucose, insulin, TNF-alpha and interleukin-6 were all evident. (As you may already know, TNF-alpha and interleukin-6 are 2 markers of inflammation in the body).
But for mice, the time the food was eaten also made a difference . When fed high fat chow and allowed to eat whenever they chose, rodents would eat throughout the night and day. These mice tended to become metabolically dysfunctional, developing obesity and type 2 diabetes, with elevated insulin levels, fatty liver and increased inflammatory status. In direct contrast, when mice were fed a high fat diet but had their feeding times restricted to the usual 8 hours at night time, they fared much better. Despite eating the same number of calories, they didn’t develop obesity, or diabetes, or have any negative changes to their metabolic health. No fatty liver. No raised blood fats. Remember, their feeding time was shorter, but they still consumed the same amount of energy as the mice who ate around the clock.
The circadian rhythm in humans directs them to eat and move during the day, and sleep at night. Circulating levels of the sleep-regulating hormone, melatonin, begin to rise at 8pm, peak at midnight, and drop to allow point by 7am. Since these are the hours for you to rest and recover, they’re potentially not the best times to eat.
Based on mouse models of energy restriction it seems that it it does matter when you eat. Coordinating your fasting and feeding periods to fit in with your normal circadian rhythm – eating during the day, not eating during the night when you should be asleep – can promote a more positive state of health.
Fasting Without Getting Furious
What about your mood? You know how it can get when you go too long without food – you can get a serious case of ‘hanger’ management issues. Is there a way to restrict your energy intake during an IF and not end up feeling totally furious?
Your pattern of fasting will probably play a role. For instance, alternate-day fasting is potentially challenging. In a short, small-scale study  women felt their mood and work performance was lowered on the day of their fast. Another study reported that hunger pangs experienced on fasting days seemed to remain constant over time . So, repeated, regular 24-hour fasts may not be feasible, or reasonable, over the long term. Instead, shorter fasting periods might be more user friendly – say with time-restricted (10hours), overnight (12 hours) or restricted intake (the 5:2 diet).
Fasting during less challenging periods, or in sync with your hormones (menstruating women take note) can also help. While there’s still the potential for feeling irritable, cold, hungry, many positive effects – increased self-confidence, inproved mood, less tension, less anger – have also been reported from the studies .
Intermittent fasting may support weight loss and better metabolic function. Think healthier levels of blood fats and cholesterol, glucose and insulin, and markers of inflammation. However it isn’t for everyone – say if you’re pregnant or are taking a whole heap of prescribed meds. There are a variety of eating patterns that qualify as intermittent fasts – from eating within a 10 hour period to restricting your energy intake for just 2 days a week. With so much choice, there’s most likely a pattern that can fit into your regular routine. As studies suggest intermittent fasting is as effective as a regular old diet for supporting weight loss, perhaps you’ll be eager to give it a go?
 Varady K & Hellerstein M (2007) Alternate-day fasting and chronic disease prevention: a review of human and animal trials.  Patterson & Sears (2017) Metabolic Effects of Intermittent Fasting  Hatori M et al. (2012) Time-restricted feeding without reducing caloric intake prevents metabolic diseases in mice fed a high-fat diet Appleton K & Baker S.(2015) Distraction, not hunger, is associated with lower mood and lower perceived work performance on fast compared to non-fast days during intermittent fasting.  Heilbron L et al (2005) Alternate-day fasting in nonobese subjects: effects on body weight, body composition, and energy metabolism.
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