Is it true that occasionally following a fasting diet can reduce my risk of heart disease?
Answers from Francisco Lopez-Jimenez, M.D.
Maybe. Researchers aren't sure why, but it seems that regularly fasting — severely restricting food and drink for a 24-hour period on one to two days a week — can potentially improve your risk factors related to heart health.
It's difficult to tell what effect fasting has on your heart health because many people who routinely fast often do so for health or religious reasons. These people generally tend to not smoke, which also can reduce heart disease risk.
However, at least one study has indicated that people who follow a fasting diet may have better heart health than people who don't. This may be because people who routinely fast show self-control over how many calories they eat and drink, and this behavior may translate into weight control and better eating choices when they aren't fasting.
Regular fasting and better heart health may also be linked to the way your body metabolizes cholesterol and sugar. Regular fasting can decrease your low-density lipoprotein, or "bad," cholesterol. It's also thought that fasting may improve the way your body metabolizes sugar. This can reduce your risk of gaining weight and developing diabetes, which are both risk factors for heart disease.
However there are concerns about the potential side effects of regular fasting for certain people or in specific circumstances.
- People with eating disorders may end up binge eating more after fasting.
- Fasting and exercising at the same time may lead to low blood sugar (hypoglycemia), which can cause dizziness, confusion and lightheadedness.
- Fasting by people taking diabetes medications can lead to severe hypoglycemia and can lead to serious health issues.
- Skipping breakfast may be considered fasting by some because it can result several hours without food, but skipping breakfast can be unhealthy and has been associated with obesity.
More study is needed to determine whether regular fasting can reduce your risk of heart disease. Most scientific evidence on fasting comes from animal, not human, studies. The studies that have been done on people are mostly observational, which has the lowest level of scientific evidence.
If you're considering regular fasting, talk to your doctor about the pros and cons. Keep in mind that a heart-healthy diet and exercising regularly also can improve your heart health.
Sept. 28, 2017
Francisco Lopez-Jimenez, M.D.
See more Expert Answers
- Arciero PJ, et al. Protein-pacing caloric-restriction enhances body composition similarly in obese men and women during weight loss and sustains efficacy during long-term weight maintenance. Nutrients. 2016;8:e476.
- Moro T, et al. Effects of eight weeks of time-restricted feeding (16/8) on basal metabolism, maximal strength, body composition, inflammation, and cardiovascular risk factors in resistance-trained males. Journal of Translational Medicine. 2016;14:290.
- AskMayoExpert. Obesity: Diet types. Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2015.
- LaRocca TJ, et al. Nutrition and other lifestyle influences on arterial aging. Ageing Research Reviews. 2017;39:106.
- Lopez-Jimenez F (expert opinion). Mayo Clinic. Rochester, Minn. Sept. 7, 2017.
- Collier R. Intermittent fasting: The science of going without. Canadian Medical Association Journal. 2013;185:e363.
- Low blood glucose (hypoglycemia). National Institute of Diabetes and Digestive and Kidney Diseases. https://www.niddk.nih.gov/health-information/diabetes/overview/preventing-problems/low-blood-glucose-hypoglycemia. Accessed Sept. 22, 2017.
- Bray GA. Obesity in adults: Etiology and natural history. https://www.uptodate.com/contents/search. Accessed Sept. 22, 2017.