Is skipping meals a bad idea or a secret weight-loss weapon? One diet trend that shows no sign of going away soon is intermittent fasting. That's when you voluntarily abstain from food or beverages other than water for a certain amount of time. Some fasting is for religious reasons, while others fast for weight loss.
But is intermittent fasting a healthy way to lose weight?
The three popular approaches to intermittent fasting are:
- Alternate-day fasting
Eat a normal, healthy diet one day and then completely fast or have one small meal the next day. Usually, the small meal is fewer than 500 calories. - 5-2 fasting
Eat a normal diet five days a week and fast two days per week. - Daily time-restricted fasting
Eat normally but only within an eight-hour window each day. For example, skip breakfast, but eat lunch around 11 a.m. and dinner by 7 p.m.
Benefits of intermittent fasting
Can intermittent fasting improve your health? Recent research has found that using intermittent fasting for weight loss may have some benefits in the short term.
It appears that fasting for a short time can produce ketosis, which is a process that occurs when the body doesn't have enough glucose for energy, so it breaks down stored fat instead. This causes an increase in substances called ketones. This, coupled with fewer calories consumed overall, can lead to weight loss. Research suggests that alternate-day fasting is about as effective as a typical low-calorie diet for weight loss.
Fasting also affects metabolic processes in the body that may work to decrease inflammation, as well as improve blood sugar regulation and physical stress response. Some research shows this may improve conditions associated with inflammation like arthritis, asthma and multiple sclerosis.
Little long-term research has been done on intermittent fasting to examine how it affects people over time. As a result, long-term health benefits or risks are unknown.
Side effects of intermittent fasting
Intermittent fasting can have unpleasant side effects. They could include hunger, fatigue, insomnia, irritability, decreased concentration, nausea, constipation and headaches. Most side effects go away within a month.
Sticking with an intermittent fasting routine can be easier for some people rather than trying to watch calories every day. Other people, especially those with busy or variable schedules, have more difficulty maintaining an intermittent fasting routine.
Is intermittent fasting right for you?
Intermittent fasting is safe for many people, but it's not for everyone. Skipping meals is not recommended for people under 18, those with a history of disordered eating, or those who are pregnant or breastfeeding. Athletes may find it difficult to fuel and refuel appropriately for an active lifestyle. If you have diabetes or other medical issues, talk with your health care team before starting intermittent fasting.
Also, note that the key to weight loss with intermittent fasting is not to overeat during your eating windows. Eating fewer calories than you expend remains the basis for losing weight.
Shortening the eating window may make it difficult to get the vitamins and minerals you need. While on this diet, it is important to eat meals made from quality, healthy ingredients, such as fruits, vegetables, whole grains, low-fat dairy and lean protein.
Intermittent fasting can be dangerous if taken too far. A technique called dry fasting restricts food and fluid intake, resulting in severe dehydration and posing serious health concerns. Malnutrition can occur if the caloric restriction is too severe, such as averaging fewer than 1,200 calories a day long term.
Romi Londre is a dietitian in Nutrition in Eau Claire, Wisconsin.
FAQs
Some studies have shown that it can lead to improved health and mild or moderate weight loss. Others suggest that fasting has no significant long-term health benefits. If you're considering intermittent fasting to improve your overall health or lose weight, it's important to understand: The plan's basic principles.
How much weight can you lose in a month with intermittent fasting? ›
If you consistently stay active while following intermittent fasting, you can lose as much as 6-8 pounds per month. This estimation is shockingly high when you consider that all you have to do is not eat for select hours throughout the day.
How fast can I lose 30 pounds with intermittent fasting? ›
How much, though, depends on what kind of intermittent fasting schedule you're following (more on those schedules, below). People who do some form of full-day fasts usually lose about 10 to 30 pounds over a three-to-six-month period, says Varady.
Does intermittent fasting really work for weight loss? ›
Intermittent fasting has been shown to help with weight loss and improve some markers of health. But it's not for everyone. If you're thinking of trying a fast, consider the pros and cons.
How long till you see weight loss with intermittent fasting? ›
That's how long it takes your body to switch from using glucose for energy to using fat for energy. Additionally, it will take your body a while to get used to this new eating schedule. So don't expect results right away. You may need to wait between 2 and 4 weeks to see or feel any results.
Can I lose 20 pounds in 2 months with intermittent fasting? ›
Yes, intermittent fasting may help you lose 20 pounds in 2 months. This involves cycling between periods of eating and fasting. This can be an effective approach as it allows you to reduce your overall calorie intake while eating satisfying meals (5).
What is the best intermittent fasting window to lose belly fat? ›
A 2023 review of research found that the 16/8 method and 16/8 combined with restricting calories were effective strategies for weight control in adults with overweight or obesity. An eating window starting before noon led to greater weight loss than one that began after noon.
Why am I not losing weight on 16:8 fasting? ›
If you've tried intermittent fasting but aren't losing weight, possible reasons why include overeating during your eating window and poor food choices. To help, you can try eating fewer calories, work on balancing your meals, or create a smaller or larger eating window.
Can you lose 25 lbs in 2 months? ›
To lose 25 pounds in two months you'll need to lose about three pounds per week. Although this is technically outside of the "safe weight loss" limit, it may be a realistic goal for those who stick to a strict diet plan the entire two months. You'll need to cut out at least 750 calories daily.
What is a realistic timeline to lose 30 pounds? ›
It's a fairly large weight loss goal and will require you to stick to a healthier lifestyle for a significant amount of time. Typically, you should aim to lose approximately one to two pounds each week. This means that in about four months or so, you'll be able to lose about 30 pounds.
Belly fat, also known as visceral fat, is not only unsightly, but also leads to many health risks, such as diabetes, heart disease or obesity. Many people choose intermittent fasting to reduce their excess belly fat.
How can I speed up weight loss on intermittent fasting? ›
A person needs to decide on and adhere to a 12-hour fasting window every day. According to some researchers, fasting for 10–16 hours can cause the body to turn its fat stores into energy, which releases ketones into the bloodstream. This should encourage weight loss.
What is the disadvantage of intermittent fasting? ›
Research has linked intermittent fasting to many health benefits — including weight loss, increased blood sugar control, reduced heart disease risk factors, and more. But side effects of fasting can include hunger, irritability, headaches, and bad breath.
What happens after 1 month of intermittent fasting? ›
One to three months of intermittent fasting may lead to weight loss, better athletic performance, improved gut, liver, and heart health, and lower inflammation. Long-term intermittent fasting is more indicated for chronic disease prevention and maintaining overall health.
What is the best fasting schedule for weight loss? ›
The 16/8 method: Also called the Leangains protocol, this involves an 8-hour eating period and a 16-hour fasting period. Some people do this by skipping breakfast, but you can also do the reverse and skip dinner or eat early. Eat-stop-eat: This involves fasting for 24 hours once or twice per week.
How long should I fast to lose belly fat? ›
Best Intermittent Fasting Method For Visceral Belly Fat
14/10 Method: Fast for 14 hours and have a 10-hour eating window daily. That means you restrict your food intake to a specific 10-hour period while abstaining from caloric consumption for the remaining 14 hours.
What to expect after 2 weeks of intermittent fasting? ›
Going too long without eating might actually encourage your body to start storing more fat in response to starvation. Mattson's research shows that it can take two to four weeks before the body becomes accustomed to intermittent fasting. You might feel hungry or cranky while you're getting used to the new routine.
What are the results of 30 days intermittent fasting? ›
One of the main 30-day intermittent fasting results is its potential to promote fat loss. By restricting your eating window, your body has a chance to burn stored fat for fuel during the fasting period. This can lead to a decrease in overall body fat percentage and a leaner physique.
