- For those who find it difficult to cut down on calories everyday, intermittent fasting can be of great help in weight loss.
- Fasting for one day and then feasting for the next two days can help reduce weight, burn fat and improve insulin secretion.
- Anti-inflammatory macrophages which encourage fat cells to burn fat was elevated during intermittent fasting.
Intermittent fasting, without restricting overall calorie intake, has been found to reduce weight and improve metabolism.
Fasting has a number of health benefits and modifying some aspects of fasting such as the duration of fasting, the type of foods we eat between fats and when to fast can help design methods of combating obesity and metabolic disorders.
Intermittent fasting has more benefits compared to prolonged fasting. But the mechanisms behind it was unclear.
‘Intermittent fasting without cutting down on calories can be a preventative and therapeutic approach against obesity and metabolic disorders.’
How is Intermittent Fasting Effective?
A research team led by Hoon-Ki Sung of the Department of Laboratory Medicine and Pathobiology at the University of Toronto in Ontario, Canada set out to find the mechanisms that favor intermittent fasting.
The conversion of white fat to brown fat seems to be the reason for weight loss and improved metabolism after intermittent fasting
White fat is essential for storing excess energy and releasing lipids whereas brown fat cells burn energy. Under certain circumstances, white fat can be converted into brown fat and can be a potential avenue to reduce obesity.
For the study the research team used mice to find out more about intermittent fasting.
The mice were divided into two groups: an intermittent fasting group which was fed for two days and then was on a fast for 1 day. The other was a control group that was fed everyday. The study continued for four months.
After 4 months, both groups of mice consumed the same number of calories and the mice in the intermittent fasting group weighed significantly less than the control mice.
When compared with controls the intermittent fasting group had a more stable glucose metabolism and insulin sensitivity
Browning of white fat cells was due to changes in the immune-related gene pathways within fat cells
. During fasting periods, there was an increase in vascular growth factor, which helps to form blood vessels and trigger anti-inflammatory macrophages. Anti-inflammatory macrophages encourage fat cells to burn fat stores and create heat and, as the name suggests, reduce inflammation.
Study co-author Yun Hye Kim said, "Strikingly, these fasting-stimulated changes in the growth of vascular cells and subsequent immune alterations occur even after a single cycle of 24-hour fasting, and are completely reversed when mice start eating again."
Previous Findings On Intermittent Fasting
- Mice fed on fasting mimicking diet four days a month regained healthy insulin production, reduced insulin resistance, and demonstrated more stable levels of blood glucose even in the later stages of the disease.
- Intermittent or alternate day fasting works better for those who can remain without food for 4 to 5 hours than those snackers who prefer a small meal every two hours.
- Intermittent fasting inhibits the development and progression of the most common type of childhood leukemia.
- A compound, beta-hydroxybutyrate, produced by the body when dieting or fasting can block NLRP3, a part of the immune system involved in several inflammatory disorders such as type 2 diabetes, atherosclerosis and Alzheimer's disease.
Further research on intermittent fasting is required for trials in humans.
In the future, research into the mechanisms at work underneath intermittent fasting could help to tailor programs to treat obesity and metabolic conditions such as type 2 diabetes.
- Kyoung-Han Kim, Yun Hye Kim, Joe Eun Son, Ju Hee Lee, Sarah Kim, Min Seon Choe, Joon Ho Moon, Jian Zhong, Kiya Fu, Florine Lenglin, Jeong-Ah Yoo, Philip J Bilan, Amira Klip, Andras Nagy, Jae-Ryong Kim, Jin Gyoon Park, Samer MI Hussein, Kyung-Oh Doh, Chi-chung Hui and Hoon-Ki Sung. Intermittent fasting promotes adipose thermogenesis and metabolic homeostasis via VEGF-mediated alternative activation of macrophage. Cell Research (2017). doi: 10.1038/cr.2017.126.