Diet - Overnight Fasting

Health Benefits

  • Improved glucose (sugar) balancing
  • Better metabolism
  • Reduced inflammation
  • Reduced cancer risk
  • Improved longevity


Overnight fasting is critically important for health and can be a huge boon to weight loss. The longer you avoid food and drink between dinner and breakfast the next morning, the healthier you will be. Studies have found that overnight fasting of at least 12 to 13 hours is associated with better glucose control. This, in turn, reduces the risk of diabetes, insulin resistance, cardiovascular disease and cancer. It also helps with weight loss and maintaining normal body weight. Eating, while necessary and important, is also a very stressful event to the body. Eating generates a huge amount of oxidative stress. This oxidative stress requires significant antioxidation. And when we eat late at night, it puts great demands on our antioxidant defenses, which can have serious repercussions. Normally, most of our cell repair and tissue healing happens at night. These processes are antioxidant-dependent. When we avoid the oxidative stress of eating, we maximize cell repair during the night. 

Furthermore, overnight fasting resets hormones that control appetite, sugar metabolism and insulin sensitivity. Improved insulin sensitivity has been clearly associated with lower risk of all chronic diseases including cancer. 

Overnight fasting is all about narrowing our eating window as much as possible. This leaves your body free to reset blood sugar balance, repair cells and restore function overnight. With that, you also get all of the other health benefits as well including weight loss!


Over the next 5 days, you will first assess how much you are fasting overnight now. Then, you will implement 4 new strategies so that by the end of this Action Step, you will establish a minimum of a 12 to 13 hour overnight fast as your new daily habit. 

Why It Works

Overnight fasting is associated with better glucose control, reduced insulin and reduced inflammation. These improvements are associated with lower cancer risk.


Marinac CR, Nelson SH, Breen CI, Hartman SJ, et al. Prolonged Nightly Fasting and Breast Cancer Prognosis. JAMA Oncol. 2016 Mar 31. 

Marinac C. Prolonged Nightly Fasting and Breast Cancer Risk: Findings from NHANES (2009-2010). Cancer Epidemiol Biomarkers Prev. 2015;24(5):783-9.

Marinac CR, Sears DD, Natarajan L, Gallo LC, et al. Frequency and Circadian Timing of Eating May Influence Biomarkers of Inflammation and Insulin Resistance Associated with Breast Cancer Risk. PLoS One. 2015 Aug 25;10(8):e0136240