Fasting has been practiced for centuries, across a number of cultures. The health benefits of fasting are well documented. But there are certain aspects to consider before you jump on board. It seems to be an easier practice for some people to adopt than others, with a few considerations to think about before you begin fasting. In this article we give you the lowdown on the benefits of fasting, and whether it’s safe.
The Benefits of Fasting
Better Brain Function
Have you noticed that you tend to be more active when hungry? Conversely, when you’ve eaten a big meal it’s likely that you’ll exhibit more sedentary behaviors. Your brain may function better when you’re hungry and physically active[i], but be careful not to interpret this as “it’s good to starve.” Precautions must be taken for safety (which we discuss in a bit…)
Studies on rats have shown evidence of enhanced brain function when fasting. Improvements in brain function were produced from alternate days of normal eating and fasting. Performance in sensory and motor function tests improved, as did learning and memory[ii]. Although the results aren’t conclusive for humans, many people who fast regularly report an improved ability to focus and think clearly.
Health benefits of fasting for weight loss
A number of people choose fasting as a method for losing weight. There is plenty of research to suggest its effectiveness. Whole day fasting trials in humans have been shown to reduce both body fat and body weight[iii]. Intermittent energy and carbohydrate restriction has also shown to improve insulin sensitivity and weight control more effectively than daily energy restriction[iv]. However other studies have shown intermittent energy restriction to be equally effective for weight loss as continuous energy restriction[v].
A small scale study on non-obese human subjects showed an increase in fat oxidation[vi]. However, hunger on fasting days did not decrease during this study. Implications like this must be considered when determining the right type of fast, or whether to fast at all. Remember that we’ll address these concerns in the second part of the article. Overall, intermittent fasting can be a useful approach for decreasing obesity levels[vii][viii].
The benefits of fasting for prevention and management of health conditions and diseases
Studies are showing that fasting may have positive effects on a range of health conditions and disease. Intermittent fasting studies on rats have produced favorable results across a wide range of disorders[ix]. These include diabetes, cardiovascular disease, cancer[x], and neurological disorders such as Alzheimer’s[xi], Parkinson’s and stroke. Although conclusions for humans can’t be drawn from these studies, they form the basis for promising early research[xii] and the potential for larger scale human studies to be conducted.
Alternate day calorie restriction (a type of fasting) in humans showed a number of beneficial effects for treating asthma[xiii]. There is also some early evidence from human studies that water fasting may be a safe and effective method for normalizing blood pressure. A study of 68 human subjects with borderline hypertension resulted in 82% of the subjects reaching a normal blood pressure reading by the end of the study. The biggest improvements were noticed in those who had the highest blood pressure readings to begin with[xiv].
As a whole, emerging research from both animal and human studies highlights a number of potential health benefits of fasting. But maybe you’re wondering “is fasting safe?” It’s time to address some of the potential downsides and considerations of fasting.
The potential dangers and factors to consider when it comes to fasting
There may be too much risk involved for certain populations
If you’re unsure whether fasting is right for you, check with your primary health care practitioner. Fasting is generally not recommended for the following groups of people[xv]:
- Those with diabetes, due to difficulties in maintaining blood sugar levels
- People who are on medications that require food intake
- Pregnant or breast feeding women due to increased caloric requirements. However a modified approach to fasting may be safe under a supervised program such as the 131 Method
- Those who are going through an active growth stage, such as adolescents
Can you enjoy the health benefits of fasting if you’re an athlete or even a regular exerciser?
Take extra care with regards to fasting and exercise. Fasting can take a while to get used to and athletes can run into problems if the fasting process is not carefully considered. Sports dieticians Australia (SDA) note that the following issues can occur[xvi]:
- The potential to reduce concentration , energy levels and performance on fasting days
- Muscle mass may decrease if an adequate level of protein is not consumed
- A negative impact on recovery due to inadequate replenishment of glycogen stores
Fasting is not generally recommended for athletes during training periods. Consider it during the off-season and periods of reduced training. If you’re not an athlete and you’re just getting started with fasting, avoid exercise on fasting days in the beginning. As you get used to it this may change. Err on the side of caution and learn about how your body personally responds to fasting over time.
Other considerations if you want to enjoy the health benefits of fasting
- If you’re new to fasting, start with a less extreme version rather than a three day water-only fast, which is an advanced level of fasting. Ease yourself into it and monitor how you feel along the way
- Consider getting professional advice about fasting or following a fasting protocol such as the 131 Method that can be adapted to meet your individual needs. This will also help educate you about important factors such as preparing for your fast, and refueling afterwards. Note that extreme forms of fasting that last three days or more should only be attempted under medical supervision
- Dehydration can be a problem if fasting is not done sensibly. This is because you’re missing out on the water content that you would usually get from food. Take care to ensure you sufficiently hydrate by consuming ample water and electrolytes
- Do you have a history of disordered eating? If so, fasting could be seen as another form of deprivation and trigger unhealthy eating behaviors. If you worry about this, consider carefully whether fasting is the best approach for you. Or, seek professional advice
- Finally, the adaptation process of fasting can produce some undesirable effects. Even in the long term it may not be the best choice for some body types. Some people experience symptoms such as headaches, reduced energy levels and increased stress levels
Health benefits of fasting – the bottom line
We’d love to hear about your experiences with fasting. What methods have you tried and enjoyed? List some of your best successes. We’d love to hear from you so please leave a comment in the box below!
The 131 Method
For more guidance on safe fasting, check out the 131 Method. We discuss how to prep, fast and refuel in the program!