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Is Fasting a Healthy Habit?

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Time-restricted dieting. Interval eating. Intermittent fasting. No matter the name, following a restricted eating pattern has become popular for people looking to lose weight and improve their health.

Is intermittent fasting (IF) sustainable and does it lead to positive benefits for total health and well-being? Cooper Clinic Nutrition discusses the pros and cons of the diet trend that could be doing you more harm than good. 

Fasting pros 

Intermittent fasting is a diet regimen that cycles between brief periods of fasting, with either no food or significant calorie reduction, and periods of unrestricted eating. There are three types of intermittent fasting: 

  • Alternate day fasting (ADF): alternates days of zero calories with days of unrestricted calories
  • Modified fasting: Also known as the 5:2 diet, you consume 20-25 percent of estimated caloric needs on fasting days and unrestricted intake on non-fasting days 
  • Time restricted feeding: prolonged nighttime fasting, typically 12-16 hours

According to experts, fasting can potentially help you live longer because of the way it works with the body’s circadian rhythm. When you fast, metabolic changes occur and the body’s cells regenerate by excreting the damaged cells and rebuilding new, healthy cells. This can potentially impact disease risk and thus, promote increased lifespan.  

A November 2018 study from the American Journal of Clinical Nutrition found those who participated in IF and those who followed a standard diet plan both lost weight and saw improvements to their HbA1C, fasting glucose and lipids levels.  

Many rodent studies have found that a 12-hour fast, in which you eat three meals in 12 hours, and the other 12 hours you fast, can be an optimal period of fasting in terms of weight and health. However, adaptations do not necessarily improve its effectiveness. 

Fasting cons

While some studies reveal the potential benefits of intermittent fasting, other research shows this eating pattern may not be safe for everyone. 

Intermittent fasting has been shown to increase the risk for hypoglycemia for those with diabetes. Since diabetes management is highly individualized, the safety and efficacy of IF would depend on your insulin dependency, medications and risk for hypoglycemia. 

Many people who participate in intermittent fasting choose to skip breakfast to prolong their fasting period. Yet, according to a study from the Journal of the American College of Cardiology, skipping breakfast has been associated with an elevated risk of cardiovascular disease and hardening of bowels. A systematic review published by the Academy of Nutrition and Dietetics found skipping breakfast was also associated with higher body mass index (BMI) and increased risk of obesity. 

Intermittent fasting is also not recommended for women of child-bearing age or pregnant and breastfeeding women, as they need consistent energy and nutrients to support the healthy growth of the baby.

Remember, meal times are golden opportunities to nourish the body on a recurring basis (think, three times a day) with what it needs: 

  • Complex carbohydrates
  • Quality protein
  • Fiber
  • Vitamins
  • Minerals 
  • Fluids

When meals are skipped, intake of such vital nutrients are forfeited which can lead to potential deficiencies.

There are a very limited number of human studies that prove the efficacy, safety and sustainability of intermittent fasting. Cooper Clinic Nutrition recommends the following when it comes to maintaining a healthy lifestyle:

  • Consume 5-9 servings of fruits and vegetables daily
  • Limit excess sweets and highly processed foods, such as fast food
  • Get an adequate amount of physical activity every week
    • At least 150 minutes per week 
    • Aim to include two days of strength training 

Before embarking on a weight loss plan, it’s important to speak with your primary care provider and a registered dietitian nutritionist for medical clearance and nutrition guidance. For more information about Cooper Weight Loss, visit or call 972.367.6100.