Intermittent fasting can be a controversial topic in the world of weight loss. While some people believe it to be unhealthy and unrealistic, there is evidence to suggest limiting your eating window can help you shed some pounds and even benefit your overall health.
However, it’s important to do it safely according to what works for you and your lifestyle.
Let’s take a look at the scientific research behind intermittent fasting, as well as the benefits, risks and results, so you can make an informed decision.
What Is Intermittent Fasting?
You’ve probably already heard of intermittent fasting (IF) as it’s arguably one of the most popular dietary trends at the moment. Put simply, it’s an eating pattern based on periods of abstinence and eating.
Why do people do it? Well, fasting isn’t a new notion. It’s been a practice for humans throughout evolution, especially for religious purposes in Islam, Christianity, Buddhism and Judaism.
If you think about it, humans were hunters in prehistoric times. Gathering a meal would take a lot of time and energy, so having to survive on limited food for many hours, or even several days, was the norm.
Intermittent Fasting Methods
With IF, it doesn’t matter which foods you eat but rather when you eat them. You won’t eat anything when you fast unless it’s a calorie-free beverage like water, herbal tea or black coffee.
The following IF methods are the most common.
- Leangains Protocol or the 16/8: This is an 8-hour eating period followed by a 16-hour fast that can be done by skipping breakfast or dinner, or eating breakfast late or dinner early.
- The 5:2 Diet: This is where you eat as normal for 5 days of the week but only consume 500-600 calories on two nonconsecutive days of the week.
- Eat-Stop-Eat: This is a 24-hour fast once or twice per week, which tends to be the most suitable for those experienced with fasting.
Reducing your eating period will typically reduce the number of calories you eat every day during IF. This can result in weight loss over time.
How Does Intermittent Fasting Work?
The average person tends to eat three meals a day, plus snacks, burning off the calories from the food they consume. They don’t burn their fat stores.
IF prolongs the period when your body has burned through the calories from your last meal. After numerous hours without food, the body exhausts its sugar stores and starts to burn fat, which is known as metabolic switching.
Let’s explore what happens in your body when you fast:
- Your human growth hormone (HGH) levels increase, which helps with fat loss and muscle growth
- Insulin levels decrease, making stored body fat more accessible
- Cellular repair processes initiate, digesting and eliminating old dysfunctional proteins (known as autophagy)
- Gene expression occurs, improving gene functioning which relates to longevity and disease prevention
In addition to the above, IF accelerates the release of the fat-burning hormone norepinephrine (noradrenaline). This can temporarily increase your metabolic rate, helping you burn calories at a quicker rate.
Benefits of Intermittent Fasting
Studies have shown that there are several benefits to IF.
Weight Loss
Most people who try IF do see weight loss over time. A 2020 systematic review of studies on people with overweight and obesity demonstrated rates of weight loss from 0.8% to 13% of their starting weight.
Even so, keep in mind that IF can lead to overeating in some cases. When you go without eating for a while, your body produces more ghrelin, the hunger hormone. This can lead to increased eating when you break your fast.
Decreased Risk of Obesity-Related Diseases
Losing weight coupled with being physically active significantly lowers your risk of obesity-related diseases, like diabetes, sleep apnea and some types of cancer.
Research shows that those with type 2 diabetes, in particular, can benefit from IF. Losing body weight through IF can lower their levels of fasting glucose, fasting insulin and leptin while reducing insulin resistance. Some studies even found that individual patients no longer needed insulin therapy.
Reduced Inflammation
It is thought that IF may be more beneficial than other eating patterns for reducing inflammation in the body. As a result, it can help conditions associated with inflammation, such as:
- Alzheimer's disease
- Multiple sclerosis
- Asthma
- Arthritis
- Stroke
Heart Health
Some research in animals indicates there are also some cardiovascular benefits of IF. It can improve blood pressure and resting heart rates, as well as other heart-related metrics.
There are some other benefits of IF in animals, such as improved thinking and memory, physical performance and tissue health. That being said, more research is needed in humans to confirm this.
Results and Risks of Intermittent Fasting
You don’t see immediate results from IF, so if you’re wanting to try it, stick with it for about 2-4 weeks.
Note you may experience some side effects that are quite common within the first few days of fasting. These include headaches, lightheadedness, nausea and insomnia. Most side effects will go away within a month.
Is Intermittent Fasting Safe?
IF is thought to be safe for healthy adults when it is done for a limited amount of time. There’s not enough research to show the long-term effects. We just know that IF wouldn’t be suitable in the following cases:
- If you have type 1 diabetes
- If you are pregnant or breast-feeding
- If you have a history of disordered eating, anxiety or depression
Check with your doctor if you have any questions or concerns regarding IF before you try it for yourself.
Final Thoughts
Intermittent Fasting is a popular eating pattern amongst fitness circles with renowned weight loss effects.
Some people prefer IF to more traditional diets as it’s easy to get into a routine rather than tracking calories every day. Others may not like to commit to periods of abstaining from food, especially if they have a busy or physically demanding schedule.
Hopefully, we’ve helped you to figure out whether IF is right for you. You could start by choosing a fasting window using the 16/8 method, such as eating your first meal around noon and your last meal before 8pm, and take it from there.
As always, health comes first so if you experience any side effects, be sure to consult with your doctor.
