An expert has provided insights into the effects of fasting on the body.
Fasting involves abstaining from food for an extended period or significantly reducing calorie intake. One popular method is the 5:2 Diet, where individuals eat normally for five days per week and restrict intake to 500-600 calories on two non-consecutive days.
Fasting offers various health benefits, including weight loss, improved blood sugar control, enhanced heart health, and better physical performance, according to Johns Hopkins Medicine.
However, opinions differ regarding fasting’s health impact, mainly due to a scarcity of human studies on the practice.
Dr. Alan Goldhamer has shared insights into what occurs in the body during the initial stages of fasting.
In a conversation with Steven Bartlett on the Diary of a CEO podcast, Goldhamer explained that within the first 24 hours of fasting, the body transitions from using glucose to ketones as a fuel source. Ketones are chemicals the liver produces when breaking down fats.
“[In the first 24-48 hours of fasting] it’s going to predominately shift the brain liver muscles are going to begin shifting – it’s a progression depending on your glycogen stores,” he detailed.
“Within 16 hours/24 hours/48 hours in that transition, you’ll be going from burning almost exclusively glucose to burning byproducts of fat metabolism.”
These byproducts include ketones and beta hydroxybutyric acid (BHB), which provides energy when carbohydrate or sugar intake is insufficient.
Besides aiding weight loss, fasting may also benefit brain health.
Goldhamer told Bartlett: “The higher your [BHB] is, the more BDNF is produced. BDNF, brain-derived neurotrophic factor, is a neurochemical that’s thought to be protective in the brain from oxidative damage.”
Oxidative damage is associated with diseases like Alzheimer’s and Parkinson’s.
Simulations have depicted the body’s response to fasting.
One specific video illustrates that within the first four hours, the body ceases digesting food.
At eight hours without food, blood sugar levels decrease, and the body utilizes stored glycogen for energy.
By 12 hours, glucose is likely depleted, prompting the liver to convert fat into ketones.
After 16 hours of fasting, a process called autophagy begins, where the body naturally recycles damaged or unnecessary cellular components.
It is essential to consult a medical professional before making significant dietary changes.