What Is Intermittent Fasting?
Intermittent fasting is an eating plan in which you alternate between periods when you eat normally and extended breaks when you eat little or no food. Some people try intermittent fasting to lose weight, while others believe it will improve their health.
There are different versions of intermittent fasting. They include alternate day fasting, 5:2 intermittent fasting (fasting 2 days each week), and daily time-restricted feeding (in which you eat only during specified hours of the day).
Some research shows that intermittent fasting works, at least in the short term. In some studies, people who followed this diet lost weight and had improvements in common health measures, such as cholesterol levels and markers of inflammation.
Studies of intermittent fasting in people with chronic disease have resulted in better control of their conditions. However, most of these studies have been relatively brief, lasting only a few months. It’s unclear if the benefits would last years if the diet is continued throughout life.
While intermittent fasting is becoming more popular, always talk to your doctor before you start a new diet.
How Does Intermittent Fasting Work?
Your body’s main source of energy is a form of sugar called glucose, which circulates in the blood. When you eat a typical diet, your body has a steady supply of sugar, primarily from carbohydrates. But when you go hours without eating, you burn up all of your stored sugar. When that happens, your body burns stored fat as fuel, which is called metabolic switching. That’s why intermittent fasting can help you lose weight and body fat.
Researchers are still studying intermittent fasting to understand the possible secrets behind its overall health-boosting benefits. One theory suggests that fasting puts your cells under mild stress, prompting them to adapt. Scientists think that this process strengthens your cells’ ability to deal with stress and potentially fight off some diseases.
Keep in mind that no one is 100% certain how intermittent fasting works. Furthermore, no two people respond the same to any given diet, so there’s no guarantee that any claims about the benefits of intermittent fasting will prove true for you. That’s another good reason to check in with your doctor before starting any new diet.
WebMD does not back claims made about intermittent fasting or any other eating plan.
Intermittent Fasting Benefits
Studies in humans have shown that intermittent fasting appears to have some important health benefits, including:
- Weight loss
- Less insulin resistance, a condition that causes and worsens type 2 diabetes
- Reduced levels of unhealthy blood fats, such as cholesterol and triglycerides, which increase the risk for cardiovascular disease
- Lower blood pressure
- Better control of inflammation, which is linked to many diseases, from Alzheimer’s disease to asthma
You may also find that intermittent fasting has some additional upsides, including:
Simplicity. Intermittent fasting doesn’t require you to count calories or carbs. You simply don’t eat (or eat very little) during certain hours or on certain days.
Adaptability. With intermittent fasting, you decide what to eat. However, it’s preferable to select healthy foods for your non-fasting periods, as you may undermine the benefits of the diet if you choose highly processed foods. You can make intermittent fasting work with food restrictions, such as if you’re vegetarian or vegan. And you can eat the type of diet you like, whether it’s high- or low-carb, or low in fat.
Savings. You’re reducing the amount of food you eat each week, so your grocery costs should go down.
Intermittent Fasting Risks
Studies on intermittent fasting have found that this approach to eating may carry some risks along with its potential benefits. They can range from simply making you feel lousy while you’re fasting to more serious threats to your health.
Side effects of intermittent fasting
Going without food for long periods can have some downsides. Some side effects that have been linked to intermittent fasting in studies include:
- Dizziness
- Nausea
- Insomnia
- Headache
- Weakness
- Mood swings
- Needing to pee frequently
Some studies have also found that participants on intermittent fasting regimens lost muscle. Doctors also caution that some people who try intermittent fasting overeat on non-fasting days or hours. If you’re older, losing too much weight could affect your bone health, immune system, and your energy level.
Intermittent fasting and heart disease
Intermittent fasting appears to improve cholesterol levels and other factors that increase the risk for heart disease. But there are some clues that some forms of this diet may actually be bad for your ticker. One form of intermittent fasting called time-restricted eating limits the period you can eat to an 8-hour window each day.
A large study reported at an American Heart Association conference in 2024 found that people who followed a time-restricted eating plan were 91% more likely to die of cardiovascular disease than others who ate a typical diet. More research on the link between intermittent fasting and heart health is necessary, but this study raises important questions.
Credit: webmd
