Benefits and Risks of Intermittent Fasting

How does intermittent fasting work?

Food is fuel, when we eat insulin levels rise, turning blood sugar (glucose) into energy or to store glucose for future use.

When we do not eat as with intermittent fasting, insulin levels fall; signaling the body to start burning stored energy. Blood glucose falls, so the body must now pull glucose out of storage to burn for energy.

Research shows that 60% of Canadians eat between meals. In the 1960’s and 70’s, the average eating intervals was 3 meals per day. By 2005, people are eating 5 to 6 times a day. This is due to the mistaken belief that smaller frequent meals will increase metabolism and aid in weight loss. Additionally, other factors include the industrialization and accessibility to more processed and fast foods and more complex social issues.

Recommended strategies

  • Simple fast: 12 hours
  • Cycle fast: 16 hours, 2 to 3x per week
  • Extended fast: 2-3 days
  • Time restricted eating: eat all meals in 8 hour period at the same time each day (circadian rhythm)
  • Fasting Mimicking diet by Dr. Valter Longo – Eating low carb, high fat, plant protein (5 days)
  • Intermittent fasting allows drinking of water, tea, coffee, and broths

Benefits of intermittent fasting

  • Boost immune system and reduce chronic inflammation
  • Gives your digestive system a break
  • Affects hormone and insulin levels, leading to decrease in body fat and weight loss
  • Helps to lower LDL cholesterol, blood pressure and triglycerides
  • Autophagy
  • Animal studies indicate potential for slowing age related cognitive decline


  • Difficult to sustain long term
  • Not recommended for pregnant or breastfeeding women
  • Not recommended for people with eating disorders or children
  • Needs to be individualized and discussed with health care practitioner, not a one fit for all
  • Recommended only with a planned nutritious diet in between periods of fasting

Marsha Fenwick, C.N.P.  R.R.T.

Marsha is not your typical nutritionist. She began her career 20 years ago as a Registered Respiratory Therapist. Later, she earned her certifications as a Registered Nutritional Consultant Practitioner, Certified Nutritional Practitioner, and Registered Orthomolecular Health Practitioner. Marsha is also a Certified Cancer Coach. Her clinical practice specializes in: sustainable healthy weight loss, digestive health, women's hormones, diabetes, heart health, and cancer prevention and recovery. For more information and to book a FREE 15 minute consultation go to

marsha fenwick nutrition