Is it true that occasionally following a fasting diet can reduce my risk of heart disease?

Answer From Francisco Lopez-Jimenez, M.D.

Maybe. Fasting means not eating or drinking for a certain period of time. Some types of fasting may improve some risk factors related to heart health. But researchers aren't exactly sure why.

Intermittent fasting is a pattern of eating as usual then not eating for a set time period. Typically, you can eat whatever foods you like. Intermittent fasting methods include:

  • Alternate-day fasting. You eat typical meals on one day and fast or eat little the next day.
  • Time-restricted eating. You eat only between certain hours of the day, such as between 11 a.m. and 7 p.m.

Research on intermittent fasting is mixed. Some studies say that it may decrease low-density lipoprotein (LDL) cholesterol, the "bad" cholesterol. Intermittent fasting also may improve the body's response to a hormone called insulin. Insulin helps control blood sugar levels. Better cholesterol and blood sugar levels can lower the risk of weight gain and diabetes — two risk factors for heart disease.

But other studies have suggested that skipping breakfast — a form of intermittent fasting — can increase the risk of heart disease. And a review of studies on intermittent fasting found that the weight and blood sugar changes reported were small and insignificant. More research is needed to determine whether regular fasting can reduce the risk of heart disease.

The side effects of intermittent fasting aren't well known. Some people say it causes a mild headache. Further study is needed to understand the long-term effects.

In general, intermittent fasting isn't recommended for those who:

  • Are underweight
  • Have an eating disorder
  • Are pregnant or breastfeeding
  • Take medicine for diabetes
  • Have a history of low blood sugar (hypoglycemia)
  • Have end-stage liver disease

If you're considering regular fasting, talk to your health care provider about the pros and cons. Remember that a heart-healthy diet and regular exercise can improve heart health.


Francisco Lopez-Jimenez, M.D.

Oct. 08, 2022 See more Expert Answers

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