016. Intermittent Fasting: Is it for me?
What is Intermittent Fasting?
The definition of Intermittent Fasting: taking intentional breaks from eating.
What are ways to Intermittent Fast?
16:8 Method: Restrict intake for 8 hours, and fast for 16. Example: eat 11 am to 7 pm.
Eat-Stop-Eat: Fasting for 24 hours, 1-2 times a week.
5:2. You consume 500-600 calories on two non-consecutive days of the week, and eat normally the other 5 days.
How does Human Metabolism work?
Glucose (or sugar) is the primary energy source for most of your tissues/cells throughout the day
Fatty acids represent an alternative fuel source for organs that are metabolically active like muscle, liver, brain, and rise overnight while you are sleeping (/fasting).
The Cycle Of Intermittent Fasting
EAT
Hour 0
Food Consumption
FED STATE
Hour 3
In the fed state, your glucose (blood sugar rises), and your pancreas secretes insulin to accomodate for the blood sugar spike.
In this state, your body stops breaking down fat to release fatty acids.
It breaks down glucose, and this is where you get your energy from.
If there is excess caloric intake, it is stored as fatty acid in the body
THE POST ABSORPTIVE STATE
Hour 18
AKA “early fasting state”
The insulin secretion has decreased, leading to gluconeogenesis (instead of breaking down sugar from carbs, breaking down sugar from fat and protein).
Increases the breakdown of fatty acids
THE FASTING STATE
Hours 36-48
Insulin secretion is down
Metabolism shifts to breaking down Fatty acids and Ketones as fuel
Lipolysis (breaking down of fats increase)
Increase glucagon (counteracts insulin, by stimulating the liver to increase glucose production, and increase blood glucose levels).
> 48 HOURS OF FASTING
Decreased insulin
Releases Fatty Acids
So, what do we know?
Nearly all IF studies have resulted in some degree of weight loss, ranging from 2.5-9.9% of fat loss
Animal studies found a decrease in serum glucose or blood sugar and insulin
The human trials showed stable or decreased fasting insulin, with no change in fasting blood sugar
Animal models show IF to be beneficial for weight, body composition, cardiovascular biomarkers, and aging, decrease inflammation, and promote longevity
The studies vary on their definition of IF, protocol, and duration of fasts.
My one question to you?
Can you maintain this?
Take-Aways
Research is not robust enough to suggest IF to patients as a standard of care.
Best recommended to people who are able to avoid overeating following a fasting period.
Americans prefer highly palatable, calorically dense foods!
Trials ongoing on cancer, alzheimer’s, diabetes, and longevity.
