Episode Details

Episode 99: Intermittent Fasting 99. 

By Danish Khalid, MS4; Sapna Patel, MS4; Ross University School of Medicine. Comments by Valerie Civelli, MD; and Hector Arreaza, MD.

Intermittent caloric restriction may seem like a new trend, but Sapna and Danish discussed that actually fasting is practiced in different cultures and it has many health benefits, including weight loss. .  

This is the Rio Bravo qWeek Podcast, your weekly dose of knowledge brought to you by the Rio Bravo Family Medicine Residency Program from Bakersfield, California. Our program is affiliated with UCLA, and it’s sponsored by Clinica Sierra Vista, Let Us Be Your Healthcare Home. This podcast was created for educational purposes only. Visit your primary care provider for additional medical advice.

D: Welcome and thank you for tuning back to our Nutrition series! Today, we want to give a shout out to one of our listeners. She brought up a topic that has recently gained public interest. Intermittent fasting. So, if you’re listening, Hina Asad, this one's for you! Let’s jump in! 

V: 2/3 women are overweight and obese. 1.5 pounds gained/yr on avg age 50-60’s.

S: So like we said earlier, intermittent fasting has recently gained much public interest as a weight loss approach. Or should I say, revitalized itself, as it has been around for years. It describes an eating pattern in which you alternate between periods of eating and fasting (or not eating). The length of each fast can vary in duration.

A: There are feasting and fasting periods, or fed states and fasting states. What is more effective: Intermittent restriction of calories or continuous restriction of calories? 

D: Before we dive in, let’s go back. We know that calorie reduction has been consistently found to produce reduction in body weight and improve overall health. We talked about how to calculate our basal metabolic rate and subtracting calories from our daily caloric intake to result in weight loss. However, this can be difficult to sustain over a long period. Additionally, it requires that you adjust your caloric needs every so often as you lose weight, which can further make it difficult. So how is intermittent fasting different from this?  

S: Well, in contrast to calorie reduction, intermittent fasting focuses on when calories are consumed and the total quantity consumed. Intermittent fasting works through an altered liver metabolism, referred to as the “metabolic switch.” It’s where the body periodically switches from liver-derived glucose to adipose-derived ketones. In doing so, it stimulates an adaptive response including improved glucose regulation, improved insulin sensitivity, and increased stress resistance via conditioning.

V: When you eat is more important than what you eat. Benefits: reducing cancer, Alzheimer's, DM risk, better sleep, less hangry(*find evidence). 

D: What happens when we fast? In our previous podcast we mentioned ketosis, but let's talk about the physiology behind fasting.

Feeding: blood sugar levels rise as we absorb food and insulin levels rise in response to move glucose into the cell. Excess glucose is stored as glycogen in the liver to convert it to fat.

S: Postabsorptive phase (6-24hrs after beginning fasting): Blood glucose and insulin start to drop. To supply energy ,the liver starts to breakdown glycogen, releasing glucose. Glycogen stores last 24-36hrs. 

V: Insulin levels are low, and fat stores are available and improves mental clarity

D: Gluconeogenesis (24hrs - 2 days after beginning fasting): Glycogen stores run out. The liver manufactures new glucose from amino acids called “gluconeogenesis” ( literally “making new glucose)

S: Ketosis (2- 3 days after beginning fasting).

A: Autophagy: “Auto” means self and “phagy” means eat. So the literal meaning of autophagy is “self-eating.”