Intermittent fasting is a popular diet and lifestyle trend that has been gaining popularity thanks to coverage on social media and in the press, paticularly in relation to the weight loss successes many well-known celebrities claim to have enjoyed as a result. However, intermittent has many benefits beyond just weight loss and weight maintenance - we explore what these are and aim to share the scientific studies which support the many claims.
What is intermittent fasting?
Intermittent fasting is an eating pattern that cycles between periods of fasting and eating. It does not specify which foods you should eat but rather when you should eat them. During the fasting period, usually lasting 16-24 hours, no food or calorie-containing beverages are consumed. Common methods include:
- daily 16 hour fasts (such as 4pm to 8am), also known as the 16/8 diet
- daily 20 hours fasts (such as 4pm to midday), also known as the 20/4 diet
- or fasting for 24 hours twice per week, also known as the 5:2 diet.
In these examples you allow yourself windows of time where you are permitted to consume calories. The rest of the time you fast, consuming only water or other calorie-free drinks such as green tea (it's imporant to mote that zero calorie drinks that contain artificial sweeteners are not recommended due to the way they interact with your body's metabolism).
The benefits of intermittent fasting
Although it is not for everyone, intermittent fasting has been shown to offer many benefits, even beyond the most popular one of weight loss.
Helping with weight loss
The popularity of intermittent fasting and the seemingly never-ending showbiz stories of weight loss may well seem to give off the vibe of yet another Hollywood fad, however, there is science - and common-sense - to support how and why this lifestyle choice works.
By reducing the number of hours in each day where you allow yourself to eat and drink you naturally reduce the opportunities for consuming calories. Therefore, if you're a late-night snacker and you limit yourself to an 8-hour window of eating from 8am to 4pm, you arm yourself with a tool to avoid the late-night snacking (of course, as with any diet, willpower and discipline are essential).
The same can be said for the full-day fasts. By reducing the number of days each week that you are allowing yourself to eat, you are likely to consume fewer calories (assuming you don't binge on the other days).
In addition to reducing your opportunities for consuming calories, weight loss is supported by the way your body responds when it doesn't have a constant source of incoming energy. When you fast, your body is forced to burn stored fat for energy instead of constantly relying on incoming calories. This can lead to a reduction in overall body fat, and can also help to improve body composition by reducing muscle loss.
Ultimately, however, the most important factor with how ANY diet helps you to lose weight is by consistent caloric deficit.
Improved Insulin Sensitivity
Intermittent fasting can also improve insulin sensitivity, which is important for regulating blood sugar levels and preventing type 2 diabetes. When you eat, your body produces insulin to help transport sugar from the bloodstream into cells, where it can be used for energy. Over time, if your cells become resistant to insulin, your body will produce more and more insulin to try to get sugar into the cells, which can lead to high blood sugar levels and eventually type 2 diabetes. Intermittent fasting can help to improve insulin sensitivity by allowing cells to "rest" from constant exposure to insulin.
Reduced risk of cancer and heart disease
Intermittent fasting has also been shown to decrease the risk of chronic diseases such as heart disease and cancer. This is thought to be due in part to the improved insulin sensitivity and weight loss that can come with intermittent fasting, but it may also be due to other mechanisms. For example, fasting has been shown to increase the production of the human growth hormone (HGH), which has been linked to a decreased risk of cancer and improved heart health.
Cancer cells feed on glucose and, therefore, by reducing the availability of glucose this may hinder a cancer cell's opportunity to grow.
Improved brain function and can help prevent Alzheimer's disease
Intermittent fasting has been found to have some other potential benefits as well, such as improved brain function and protection from Alzheimer's disease. Some studies have found that intermittent fasting can improve cognitive function, including memory and focus.
Thanks to a process called 'metabolic switching' fasting helps to increase neuroplasticity in the brain, which can improve brain health and resistance to diseases.
Increased longevity and reduced fraility
Further studies have shown that intermittment fasting may also increase longevity by promoting cell repair and reducing inflammation. By giving your body more time to focus on repair rather than processing food it can remove more of the waste that is responsible for cellular damage.
It can help to reduce inflammation
Research has shown that intermittent fasting can help help to reduce inflammation. While some inflammation can be helpful for our body to fight infections, too much can cause diseases such as diabetes, multiple sclerosis (MS) and inflammatory bowel syndrome.
Are there any risks or concerns about intermittent fasting?
It's important to note that while intermittent fasting can provide many benefits, it is not for everyone, and should be approached with caution. People with certain health conditions, such as diabetes, should speak with their doctor before starting an intermittent fasting regimen. Additionally, women who are pregnant or breastfeeding, those under 18, anyone with a diagnosed eating disorder or suffering from a disease should avoid fasting.
How might a vegan diet impact my approach to intermittent fasting?
Vegans can be more prone to deficiencies of some vitamins and minerals, such as B12, Iron, Zinc, Calcium, Vitamin D3 and more, and therefore it's important to ensure that any changes to your eating regimen do not negatively impact your health and your body's ability to access the materials it needs to maintain itself. If in doubt consult your doctor or speak to a medical professional. You can also arrange vitamin blood tests that you do from the comfort of your home.
If in doubt, a high quality multi-vitamin supplement can give you peace of mind.
Vegans also need to take into consideration the timing of their meals. Fruits and vegetables, which are high in vitamins and minerals, are best eaten in moderation. They digest faster than other plant-based foods and can be used to fill you up.
10 tips for a successful intermittent fasting diet
Luckily, there are a handful of tips and tricks to help you make the most of your fasting days.
- Start with a shorter fasting period and gradually increase the duration as your body adjusts. Suddenly and dramatically changing your dietary routine is where most people come unstuck. If your aim is a 16/8 split (16 hours of fasting) and you're currently eating for 16 hours (only fasting while sleeping, for example) then trying increasing your fasting hours over a 2-3 week period. Your body will adjust over that time.
- Drink plenty of water and non-caloric fluids during the eating window to stay hydrated. This helps you to feel less hungry and stay focused on your next meal. In addition, it aids in digestion.
- Be consistent with the timing of your fasting and eating periods to regulate your body's hunger cues.
- Avoid overeating during the eating window to prevent weight gain.
- Incorporate nutrient-dense foods into your diet to ensure adequate nutrient intake. Legumes provide carbohydrates and proteins. They are low in calories and can be paired with fruits and vegetables, they can help you stay full for a longer period of time.
- Incorporate physical activity into your routine to help improve overall health and weight loss.
- Avoid snacking during the fasting period to prevent breaking the fast.
- Listen to your body and adjust the plan as needed.
- Don't be too restrictive. Intermittent fasting should be sustainable and enjoyable.
- Consult your doctor if you have any health concerns before starting intermittent fasting.
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This video from Alila Medical explains how intermittent fasting works and the effects it has on your body in a simple, animated way.