With diets your specialist may recommend, there will always be a science and an argument both approving it and opposing it; ultimately, no single diet is going to suit everyone. The same can be said for intermittent fasting. Fasting can be taken to extremes, such as not eating for a whole day/days. However, small periods of fasting e.g. ten hours, can be beneficial to your health and digestive system.
Factors such as gender and weight can affect fasting and it is important to know that while it may work for one person, it may not for another. The key is to do your research, and if you decide to give fasting a try, don’t be afraid to experiment.
In this article we will discuss the negatives to fasting right upfront, as to emphasise any potential pitfalls and provide you with tips on how to avoid them. Thereafter, we’ll review the pros.
1. Suppression of Hunger-Reducing Hormones
There are a number of hormones at play in the body that regulate hunger, appetite, and satisfaction after a meal. In the long-term, you need your hunger hormones working if you want optimal body composition.
A side effect of certain extended fasting protocols, is that your hunger hormones get out of balance, leading you to become unresponsive to cues that tell us you’re full and should stop eating. For example, if cells become insensitive to leptin or insulin, your brain won’t register satisfaction and hunger will remain elevated.
Most people who experience altered hunger hormones in response to fasting will find themselves battling an uncontrollable appetite. Then, once they do eat, satisfaction cues that should tell them to stop eating won’t register. This makes binging a common side effect. Once people understand that they need to alter their fasting protocol or go back to more regular eating patterns, their hunger hormones will take some time before they start working for them again.
How to avoid: Don’t fast for extended periods of time but rather opt for a more moderate approach in which you only eat for a 10 - 12 hour eating window where you will receive the benefits of fasting such as fat burning and insulin sensitivity, without the suppression of hunger hormones.
2. Excess stress and insomnia
When you go without food for a long period, you will activate the flight-or-flight sympathetic nervous system and increase cortisol secretion for your body to mobilise energy stores. For some people, e.g. those who are overweight, this could prove beneficial since it improves the body’s ability to burn fat for fuel. However, for those who suffer from high stress or who have an elevated cortisol curve, skipping meals and abnormal eating patterns may increase stress.
High cortisol triggers food intake, and leads to strong cravings for high-carb foods. The combination of fasting and cortisol can produce obsessive thoughts about food, which in turn raises anxiety, causing further release of cortisol. Preoccupation with food can turn into disordered eating pretty quickly.
Finally, the combination of high cortisol and activation of the hypocretin neurons, which incite wakefulness, can trigger insomnia and trouble sleeping.
How to avoid: Establish a healthy eating pattern with frequent meals eaten at the same time each day. This should allow you to avoid hunger and cravings and get your cortisol in check prior to starting a fasting protocol.
3. Reproductive Hormone Imbalances
It’s been shown through animal experiments that females don’t respond well to fasting. Female rats that are deprived of food “masculinise.” This means they become infertile, hyper alert, and sleep much less. Research suggests that when their bodies detect a starvation state, they develop traits that will help them find food.
There isn’t enough sufficient data on humans’ reproductive hormones and the effects of fasting.
Studies done within the Muslim community during the Ramadan fast show an increase in the amount of women experiencing differences in their menstrual cycle from fasting. The Muslim men who fasted showed significant alterations in testosterone release over Ramadan, suggesting changes of circadian function. This is logical based on how sensitive the human biorhythm is to the slightest changes in eating and sleeping behavior.
How to avoid: Athletes, leaner individuals, and those with more stressful lifestyles are the populations who are most at risk for sustained alterations to reproductive function from fasting. A time-restricted eating model is the best alternative that may not negatively affect androgen hormones, and it’s best to stick to an eating window of 10 - 12 hours. Obese individuals are less likely to experience problems and may even benefit from fasting because a reduction in body fat can significantly improve reproductive capacity.
1. Fat loss
The most compelling benefit of correctly using intermittent fasting is that you consistently lose fat. In fact, some studies show that losing fat through fasting protocols may be more sustainable as opposed to calorie-cutting diets. This can be seen as a game changer since conventional diets have poor success rates with a high likelihood of weight regain.
You can fast easily with a calorie cycling protocol, or a moderate eating window plan. An example of calorie cycling would be to do alternate day fasting (ADF) or the 5:2 model.
With ADF, people alternate between days in which they eat normally as much as they want and days in which they restrict calories to about 500. A moderate eating window could be anything from a 8 - 10 hour eating window during the day, calculating to a 14-16 hour fast for day.
2. Metabolic health: restore insulin sensitivity and lower cholesterol
Besides possibly being easier to stick to than your typical low-calorie diet, fasting can be used to improve metabolic health by restoring insulin sensitivity, lowering glucose and reducing belly fat.
This combination is a blessing for health and diabetes prevention because when your cells are resistant to insulin, your body is much more likely to store the food you eat as fat. Insulin resistance also produces inflammation, causing serious health problems.
3. Fat burning and metabolic flexibility
One of the best things about certain fasting protocols is that they allow you to become metabolically flexible so your body is easily able to burn body fat. Being metabolically flexible may be the missing link in many fat loss programs because it reduces hunger and food cravings, while improving metabolism and brain function.
Findings reported that the use of intermittent fasting for athletes showed that after 18 hours without food, fat burning increased by 50 percent.
How to make it work for you
Plan how and what you eat in a structured, organised fashion to minimise hunger but optimise energy levels in order to achieve and maintain optimal body composition. Test what method will work better for you as the key is to customise your plan to your unique goals and preferences.