At a Glance
- Science suggests that intermittent fasting can improve health of both body and mind.
- Intermittent fasting is an effective weight loss tool
- Intermittent fasting is all about YOU taking control of your diet – not the diet controlling you.
Intermittent fasting has got the health and fitness community all fired up and it’s become one of the hot topics of the moment. Many are adopting this practice to kick start weight loss or turn around their general health and wellbeing.
Experts have seen promising results using fasting therapy for treating and preventing disease. (source)
If you’ve heard all the chatter and want to get clued up, check out the beginners guide to intermittent fasting.
What’s the Deal with Intermittent Fasting?
Intermittent fasting isn’t about what you eat, its emphasis is on when you eat. Also known as “cyclic fasting”, it involves a rotational sequence to determine when you eat (also termed “feed”) and when you fast.
There are many different approaches to intermittent fasting. If it suits your lifestyle you can skip meals or even refrain from eating for an entire 24 hour period. When you think about it, everyone fasts when they sleep – you don’t eat for a period of around eight hours, after all how do you think breakfast got its name?
You might think intermittent fasting is a new idea, but in actual fact it’s been around for years.
Fasting Forms a Big Part of Many Religions
Christians observe restrictions during Lent and the Jewish abstain from eating for Yom Kippur. In Buddhism, monks often fast when they are in deep meditation and Muslims respect the Islamic month of Ramadan which involves not eating or drinking from dawn until sunset. (sources 1, 2)
Going way back to the times of the cavemen, they didn’t have the convenience of a local grocery store – no food meant they had to fast until the famine was over.
Back to the modern day, patients preparing for surgery are told to fast as a safety measure. (source)
So as you can see, there are many ways intermittent fasting is already a part of our lives.
Options for Intermittent Fasting
With intermittent fasting, there isn’t a “one size fits all” approach, this means you will have plenty of variations to choose from.
The general concept entails dividing either your week or your days into set periods when you are allowed to feed and when you have to fast.
In some intermittent fasting plans you are allowed a very restrictive calorie intake whereas others involve avoiding food altogether.
I’ve put together the most popular intermittent fasting protocols to give you an insight into what you can expect.
#1 The Warrior Diet
This method involves a once-a-day meal strategy and prioritises certain food groups. Your meal can be eaten in aset four hour window – preferably the evening time.
The remaining 20 hours are deemed the fasting period although you are allowed to munch on raw fruit and vegetables and small amounts of protein throughout this time.
The Warrior Diet is a popular choice for intermittent fasting fanatics because even though you are fasting you can snack to help you get through. That said, some people do struggle with the restrictions on what you can eat and the time allocated for eating.
#2 The 16/8 Fasting Method
This concept is great if you are new to fasting. The basic principles are fasting for a period of 16 hours (men) or 14 hours (women) and restricting your “feed” time to the remaining 8 or 10 hours. While fasting the rule is no food whatsoever but you can drink beverages without calories such as unsweetened tea.
There are no set rules for when you have to fast, however most people find not eating after dinner and avoiding breakfast is the most straightforward approach.
The flexibility of when you can eat appeals to many, although if you are someone who can’t leave the house without eating breakfast it can be a challenge to break this habit.
#3 Eat-Stop-Eat
With this fasting protocol you choose one or two days per week to abstain from eating for 24 hours straight, although you can consume calorie free drinks. On the remaining five days your healthy eating habits can carry on as normal.
For many this plan is simple to follow and not having to count calories is a plus. On the downside, some people find the 24 hour fasting period a bit of a stretch.
#4 The 5:2 Diet
With the 5:2 diet you pick two days of the week to restrict your food intake. For women, the calorie limit for fasting is 500 calories and for men it’s 600 calories. The other five days you eat as normal.
If weight loss is your goal, this plan gets positive results for most who try it. That said, you still have to exercise some self control and not go overboard and binge on junk food on your feed days.
Intermittent Fasting Boosts Weight Loss
One of the main reasons people choose intermittent fasting is to kick start weight loss. (source)
As you can see, despite having different strategies the sole aim with all of these intermittent fasting protocols is to encourage a calorie deficit. In fact, intermittent fasting can boost weight loss in three key areas – calorie reduction, fat burning and metabolism.
#1 Calorie Reduction
Obviously fasting for any length of time will lower your overall calorie intake unless you are eating in excess during your feed periods. When you look at the studies, you can see why people are making the smart choice to try intermittent fasting.
Although research is limited, results are promising. Whole day fasting trials lasting between three to six months have shown a significant reduction in body weight: up to nine%. (source)
Experts have also compared intermittent fasting to a normal diet. Volunteers followed the 16/9 method for a period of eight weeks. Within this timeframe fasting volunteers displayed a greater reduction in body fat than the control group and also maintained muscle mass. (source)
One of the pitfalls to any diet is as you lose weight you also run the risk of losing muscle. Studies suggest intermittent fasting may just buck the trend and is more likely to retain muscle mass than conventional dieting. (source)
#2 Fat Burning and Increased Metabolism
Reduction of calorie intake is only half of the equation, intermittent fasting can also rev up your fat burning and your metabolism.
Your body glucose from the foods you eat as fuel for energy production. When you fast, food consumption is restricted and it follows that your energy supply is diminished.
This means the body goes on the hunt for any stores it can find, first using what’s saved in the muscles, then heading straight for the fat cells. This is how intermittent fasting primes fat burning.
Numerous studies also suggest when the body reaches a point of starvation the lack of sugar in the blood triggers a biological process which ups the metabolic rate. (sources 1, 2, 3)
When you stack up the science it stands to reason why intermittent fasting is so effective when it comes to weight loss.
However, it’s worth bearing in mind the weight loss will only be successful if you keep a check on your “feeding”. Intermittent fasting doesn’t give you the green light to eat everything in sight between fasts.
Intermittent Fasting Impacts Hormones and Cells
Intermittent fasting is not just about dieting, it affects many biological processes within the body too. Let discuss what happens to your body behind the scenes when you fast.
Growth hormones are made by the pituitary gland. They are responsible for maintaining and building lean muscle mass as well as bone density.
Studies suggest that intermittent fasting enhances secretion of these hormones. This could be part of the reason why when you fast you lose weight but still retain muscle. (source)
Testosterone is often touted as the sex hormone. It plays a big role in the male body, having an effect on reproduction, libido, and muscle mass. (source)
Intermittent fasting increases levels of both testosterone and its precursor luteinizing hormone (LH). In fact in one study after only 56 hours of food deprivation, results indicated an increase of 180% in testosterone and 67% in luteinizing hormone. (sources 1, 2)
Leptin is a hormone produced by fat cells. It sends signals to the brain to control appetite. Leptin concentrations are in proportion to the fat stores you have in your body, meaning the more fat you have the higher your leptin levels.
Having too much leptin in your body can lead to leptin resistance. This means the body doesn’t listen to the signals and eating continues. Leptin resistance is thought to be a factor in obesity. (sources 1, 2, 3)
Fasting leads to a gradual decline of leptin which results in a lower chance of resistance. (sources 1, 2)
Insulin is a hormone which is generated by the pancreas. When levels of insulin are too high it encourages fat storage and also lowers utilization of fat for energy. Our insulin levels rise when we eat therefore it stands to reason that intermittent fasting will force levels to plummet. (source)
Autophagy is a metabolic process where the body consumes its own tissue. It may come across as a negative action, but actually it’s a positive. Autophagy is the body’s way of removing toxins and recycling cells to restore them; think of it as a deep clean.
Intermittent fasting is a well recognized way of inducing autophagy and cell repair. (sources 1, 2)
It’s these different biological mechanisms which pave the way for a number of intermittent fasting’s benefits to health
Intermittent Fasting Fights Inflammation
There is increasing evidence that chronic inflammation is an underlying cause for many diseases. (source) Diabetes, cardiovascular and autoimmune conditions are all illnesses complicated by chronic inflammation.
An investigation into the relationship between pro-inflammatory markers and intermittent fasting was carried out. Although the research is limited, there are signs which point towards intermittent fasting fending off inflammation.
The levels of interleukin-6 (IL6), C-reactive protein (CRP) and homocysteine were reported to be significantly lower in the fasting group in comparison to the non-fasting group. (source) This demonstrates intermittent fasting has a positive effect on the inflammatory status within the body.
A high fat diet and fasting were compared side by side. Results indicated intermittent fasting induces anti-inflammatory effects whereas a high fat diet has the opposite effect. (source)
Asthma is a disease involving inflammation of the airways. Clinical findings suggest intermittent fasting could have beneficial effects in asthma sufferers because it reduces inflammatory responses. (source)
Intermittent Fasting keeps the Heart Healthy
In the US, 630,000 people die as a result of cardiovascular disease each year. This equates to 1 in every 4 deaths. (source)
Intermittent fasting can help you maintain a healthy heart by fending off major players that increase risk. (source) One study carried out during the Ramadan fast clearly showed a reduction in body weight and a decrease in blood pressure at the end of the fasting period. (source)
Significant improvements were also recognised in both types of cholesterol. Research suggests that intermittent fasting can increase HDL (“good”) cholesterol levels and decrease LDL (“bad”) cholesterol. (source)
Experts note intermittent fasting also has cardioprotective properties. Observations during animal studies showed an increase in secretion of the protein adiponectin. This vital component protects the heart tissues from ischemic injury. (sources 1, 2, 3)
In fact, due to such promising results, experts suggest intermittent fasting is a viable option to help obese people both lose weight and decrease risk of cardiovascular disease. (source)
Intermittent Fasting Could Prevent Cancer
Cancer is the second most common cause of death in the US. (source) Scientists are constantly trying to determine a solution for this life threatening disease and fasting could hold some positive answers.
Evidence is emerging that certain changes in frequency and time of eating eat could reduce the risk of breast cancer. (source)
High levels of C-reactive protein (CRP) are associated with an increased risk of breast cancer. Taking this point on board, experts examined eating patterns in relation to CRP levels. (sources 1, 2)
Results depicted a 3% rise in CRP levels for every 10% increase in calories. On the other hand, a longer night time fasting period decreased CRP by 8%. (source)
This information implies that intermittent fasting could reduce systemic inflammation and therefore breast cancer. (source) A number of other studies suggest intermittent fasting promotes antioxidant effects and inhibits cancer growth. All are factors which may help prevent cancer development.
In addition to prevention, intermittent fasting has even been shown to make certain chemotherapy treatments more effective. When patients fasted in combination with chemotherapy treatment cancer cells became more vulnerable and healthy cells were protected. Side effects associated with the therapy were reduced and a faster recovery observed. (sources 1, 2, 3)
Intermittent Fasting Improves Cognitive Health
In addition to keeping your heart healthy your brain could also benefit from intermittent fasting.
Intermittent fasting increases production of BDNF – brain-derived neurotrophic factor, a hormone which boosts resistance in brain cells. Fasting also increases the number of new brain cells generated. (sources 1, 2)
According to science, you concentrate better on an empty stomach. Experts carried out a 48 hour blind study on near-total calorie deprivation. There were no detectable mental impacts from fasting, not even when testing for cognitive function. (source)
In fact one study goes as far to say intermittent fasting actually improves brain function. (source)
You might assume fasting enhances mood swings and irritation simply because of hunger however studies suggest the opposite. Intermittent fasting has been shown to significantly decrease tension, anger, confusion and total mood disturbance. (source)
If your memory is bad, you might want to try going hungry to improve it. Hunger stimulates the gut hormone ghrelin to regulate appetite. However, it also helps to bind together brain cells that form memories and learning capacity. (source)
Intermittent fasting may even protect the brain against Alzheimer’s through its anti-inflammatory actions. (sources 1, 2)
Intermittent Fasting Lowers Blood Sugar Levels
Blood sugar levels are determined by the foods you eat and how well your body can process them.
Energy from food comes mainly in the form of carbohydrates. Digestion breaks them down and converts them to sugar which passes into the bloodstream. Insulin then plays the role of transporter, moving the sugar through the body and depositing it where it’s required most for energy.
Studies suggest intermittent fasting has beneficial effects on the regulation of blood sugar levels, which in turn could have a positive influence on insulin resistance. (source)
As insulin resistance is closely linked to type II diabetes, it suggests intermittent fasting could be beneficial for those with a high probability of the condition. (source)
In fact, in one study volunteers with type II diabetes fasted for approximately 17 hours per day over a period of two weeks. Results indicated that intermittent fasting not only decreased calorie intake which encouraged weight loss, but also blood sugar levels decreased. (source)
Intermittent Fasting Could Slow Down the Effects of Aging
With all the health benefits intermittent fasting brings to the mind and the body, it’s fairly safe to assume increased longevity can be added to the list. However, science says the signs of aging could also be stalled with intermittent fasting. (source)
It’s been well documented that dietary restriction prolongs lifespan through various pathways. However it’s these very same mechanisms which are now being recognised for slowing down the aging process. (source 1, 2)
The Practical Benefits of Intermittent Fasting
Eating healthy or dieting can be very taxing on the brain. All that weighing and counting calories can soon get very tiresome. Yet with intermittent fasting, there is none of that. It’s kept simple – you fast or you feed.
Another benefit is that you should end up saving yourself a few bucks. Diets can work out to be expensive. Going all out to buy special ingredients, organic food and the likes can soon mount up. Yet with intermittent fasting you cut meals out altogether therefore you should be spending less.
You also save yourself a whole lot of time. Think about it, you don’t need to prepare and cook so many meals, and you are saving time by not stopping to eat them.
Intermittent fasting is a flexible strategy – you choose how long you want to fast for. At the end of the day choose whatever works best for you, fasting can be tailored to fit your lifestyle.
The Downsides of Intermittent Fasting
Intermittent fasting has drawbacks just like any healthy eating plan.
Hunger is the main major downside of intermittent fasting. The main reason many people give up intermittent fasting is because of the fear of feeling hungry all the time. (source)
The first few days of transition normally take some adjustment. Although everyone’s experience is different there is period where you may feel certain short term side effects from intermittent fasting:
#1 Headaches are par for the course when you start out on intermittent fasting. It’s partly down to a slight rise in stress hormones but it could also mean you aren’t properly hydrated. (source)
#2 Growling Stomach is perfectly natural to experience while fasting. After all, your body is reminding you it’s time to eat. Over time this will pass and your system will get used to the new routine. Keep drinking plenty of fluids to trick your belly into thinking it’s full.
#3 Constipation is something that many people initially experience. However when you are putting less in, it stands to reason not as much will be coming out the other end. If you have any concerns, mild laxatives may help things along.
#4 Some people feel Irritable or lethargic in the early stages, however this will pass and you will soon feel energized.
Having said all this, intermittent fasting isn’t deemed to be dangerous just remember it’s important to listen to your body.
Common Questions
Do you have a burning question about intermittent fasting? I’ve put together a list of the most popular:
#1 Can I Still Hit the Gym When Fasting?
Yes you can. Exercise is also great way to ensure you retain as much lean muscle mass as possible while you are slimming down.
#2 What Can I Drink When Fasting?
Hydration is very important when intermittent fasting. Not only will it help keep hunger at bay it will fend off headaches. Any kind of calorie-free drink can be consumed.
Water, tea and coffee are all fine – just remember no sugar and limit the milk.
#3 If I Fast, Will My Body Go into “Starvation Mode”?
No it won’t. Fasting drives the body to use up energy stores. This means the body heads for any short term supplies, then it hits the fat reserves. As far as metabolism goes, studies have seen an increase in resting rate of 8%. (source)
#4 Should I Be Afraid of Losing Muscle?
You don’t need to be too worried. Intermittent fasting causes less muscle degradation than regular methods of weight loss. However to safeguard your efforts combine resistance training and keep your muscles fuelled with protein. (source)
#5 Is It True I Can Eat What I Want When Fasting Is Over?
Many intermittent fasting protocols don’t have a set diet plan for what you can eat during feed periods. The theory is as long as you are maintaining a deficit in calories you should lose weight.
This is one area of intermittent fasting that scores points with many however, this is also where it can fall down. When you are hungry it’s very easy to make bad food choices. Keep treats to a minimum and plan for a well balanced healthy meal to break your fast.
Precautions to Consider with Intermittent Fasting
On paper the principles of intermittent fasting sound like a no brainer, however for some people it’s best to steer clear of the practice.
Intermittent fasting should be avoided if:
- You are breast feeding
- You have an eating disorder or a history of disordered eating
- Are underweight
- You are pregnant
- You are under 18
If you are underweight, pregnant, breastfeeding or still of a developing age extra nutrition is vital therefore cutting out meals through intermittent fasting is not advisable.
Fasting is also best left alone for anyone who has vulnerability towards eating disorders such as anorexia nervosa or bulimia. Studies suggest fasting for weight control is a potent predictor of risk for the onset of eating disorders. (source)
Also, if you have any of the following conditions, it’s best to check with your doctor before commencing intermittent fasting:
- Diabetes
- Low blood pressure
- Taking any form of medication
- Issues with regulating blood sugar levels
- Thyroid problems
If you already suffer with low blood pressure, the lack of food when intermittent fasting can lower it even further. This is potentially quite dangerous.
Fasting also affects thyroid secretion, therefore if you have a pre-existing thyroid condition, it’s best to seek medical advice beforehand. (source)
Certain medications require administering with food, which poses a problem if you are fasting.
Intermittent fasting can be more complicated for those suffering from diabetes or blood sugar irregularities. That’s why it’s best to chat with your doctor first to discuss whether it’s right for your situation.
Intermittent Fasting – Is It Worth It for Women?
Some research suggests intermittent fasting may have gender specific benefits which give men the edge over women. In one study, fasting improved insulin sensitivity in male volunteers but had no effect on women. (source)
Furthermore, blood sugar control was seen to deteriorate in the female group where as it remained unaffected in men. (source)
After all, intermittent fasting has a big impact on hormones. This means if it’s not carried out correctly it could disrupt women’s natural cycle. (source) Research clearly indicates after only two weeks of intermittent fasting female rats had a disrupted fertility cycle. It took up to 11 weeks to restore back to normality. (source)
In human studies, up to 30% of participants reported irregularities in menstrual cycles whilst fasting. (source)
With this kind of information, it just goes to show if you are trying to conceive, fasting may not be the best approach. Also not forgetting religion, many faiths acknowledge pregnant or nursing women should be excluded from fasting. (source)
When taking on board these valid points you can see there is plenty stacked up against women using intermittent fasting. However, when experts describe fasting as safe lifestyle regimen which can improve women’s health in many ways, there is no reason why healthy women can’t try it, bearing these points in mind. (source)
Want to Get Started?
So you’ve decided to step up and give intermittent fasting a go, which means you need to ask yourself a few questions
#1 Which Intermittent Fasting Method Do You Want to Try?
As you know, there are plenty to choose from, although I find the 16/9 method is a great one for beginners.
#2 How Long Do You Want to Fast For?
Try fasting for one day per week and if that goes to plan, gradually build up more fasting days. This way it’s not such a shock to the system and you will be more likely to continue.
#3 Do What Works for You
The best thing about intermittent fasting is that you can tweak fasting times to suit you. If your schedule works better with different feeding times then simply change it. There is no right or wrong with fasting.
Here are some more top tips to help you through intermittent fasting:
- Listen to your body
- Drink lots of fluids
- Keep yourself busy
- Don’t change your schedule because of fasting
- Give yourself time to adjust to fasting
- Be mindful about what you eat when you break the fast
Is Intermittent Fasting for you?
Make no mistake intermittent fasting isn’t the right choice for everyone. Despite this fact, it can be an effective way to kick start weight loss and simplify lifestyle with some added health benefits to boot. For this reason many people give it a shot.
However, now that you’ve got all the science and the information to hand, you can make an informed decision as to whether the hunger gains are right for you.
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