8 Health Benefits of Intermittent Fasting

Medically Reviewed By William C. Lloyd III, MD, FACS
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  • Can intermittent fasting lead to weight loss? Yes. Limiting when you eat can lead to weight reduction and improvements in overall health, even if you don’t change what you eat.

    That’s one reason why 16/8 intermittent fasting—abstaining from food 16 hours per day and eating only during a scheduled 8-hour window—is so popular. Other intermittent fasting schedules, including the 5/2 method (severely restricting calories two days per week and eating freely the other five days) and 4:3 intermittent fasting (24-hour fasting three days per week) are also linked to improved health.

  • 1
    Increased Metabolism

    The human body isn’t really designed for 24-hour access to food. Our bodies evolved to withstand times of scarcity, and scientists now know that the body shifts its metabolism during periods of fasting. Normally, the body burns glucose for energy; when carbohydrates (which break down into glucose) aren’t available, the body uses stored fatty acids and ketone bodies instead. This process is called ketosis and it’s a very efficient means of energy production.

    According to Harvard Health, eating meals earlier in the day and extending the overnight fasting period can improve metabolism.

  • 2
    Improved Blood Sugar Control
    Blood sugar test

    Scientists have known for a while now that intermittent fasting leads to healthier blood sugar levels, but they weren’t sure if that improvement was the result of weight loss or directly attributable to the fasting process.

    To find the answer, researchers calculated the calorie needs of eight prediabetic men and allowed the men to eat those calories between 8 a.m. and 2 p.m. over a five-week period. The men didn’t lose weight, but their blood sugar levels improved significantly.

  • 3
    Weight Loss
    Young man looking at himself in full-length bathroom mirror

    According to a 2017 study published in JAMA Internal Medicine, people who follow an alternate-day fasting plan—eating approximately 500 calories one day, then feasting as desired the next day (and repeating that pattern throughout the week)—typically lose 3 to 8% of their body weight over 3 to 12 months.

    For some people, intermittent fasting is preferable to typical diets that require daily calorie counting. If you dislike counting calories, intermittent fasting might be your key to weight loss.

  • 4
    Improved Blood Pressure
    Female doctor taking patient's blood pressure

    Doctors have long noticed that people who fast regularly as a religious practice also often have healthy hearts, leading some to wonder if intermittent fasting might be a technique that could be used to prevent heart disease. At first, the answer wasn’t clear because religious people who fast tend to live fairly healthy lives overall; few are heavy smokers or drinkers, so maybe abstinence (or moderate use) of tobacco and alcohol accounted for their robust heart health.

    Medical studies have since shown that intermittent fasting can lower blood pressure as effectively as blood pressure medication.

  • 5
    Decreased Inflammation
    Young woman eating a healthy breakfast

    According to an article published in The New England Journal of Medicine, cells within the body respond to intermittent fasting by shifting into repair mode. Inflammation—a risk factor for heart disease and diabetes—is tamped down.

    When people eat on a regular basis, the body doesn’t have time to shift into a fasting-and-repair mode, which may be one reason why diabetes and heart disease are so much more common today than even a century ago.

  • 6
    Brain Benefits
    Woman doing jigsaw puzzle on table

    During periods of intermittent fasting, the body burns ketones for energy. Ketones stimulate the expression of a protein that supports the growth and survival of neurons, specialized brain cells that transmit nerve impulses. Some animal studies have shown intermittent fasting can improve animals’ memory and ability to navigate challenges, such as a maze. A few studies have shown human brains may benefit from intermittent fasting as well. Two studies have noted improvements in verbal memory; at least one has also shown improvement in overall thinking.

  • 7
    Cancer Protection
    Nurse with young woman getting mammogram

    Intermittent fasting probably can’t cure or completely prevent cancer, but fascinating research suggests limiting food intake may slow the development and growth of cancer. According to The New England Journal of Medicine, “Numerous studies in animals have shown that...alternate-day fasting reduces the occurrence of...tumors.” Animal studies also suggest fasting may slow the growth of existing tumors—and increase their sensitivity in chemotherapy and radiation.

    Scientists are currently studying intermittent fasting in patients with breast, ovarian, prostate, endometrial, colorectal cancers, and glioblastoma, a type of brain cancer.

  • 8
    Decreased Cholesterol
    Diet food of fruit and vegetables for cholesterol control

    According to Mayo Clinic—and a 2009 medical study—regular fasting can decrease so-called “bad” cholesterol levels (low-density lipoprotein, or LDL cholesterol). High LDL levels are linked to increased risk of heart disease, including heart attack and stroke, so doctors encourage patients to keep cholesterol levels within healthy limits. If cholesterol levels creep up, doctors typically prescribe cholesterol-reducing medication.

    Some patients have found intermittent fasting allows them to lower their cholesterol levels without medication.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 May 20
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
  1. Cancer and Fasting/Calorie Restriction. UCSF Osher Center for Integrative Medicine. https://osher.ucsf.edu/patient-care/integrative-medicine-resources/cancer-and-nutrition/faq/cancer-and-fasting-calorie-restriction
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10 Intermittent Fasting: Is It For You? Johns Hopkins Medicine. https://www.hopkinsmedicine.org/news/articles/intermittent-fasting-is-it-for-you