A new study from the University of Illinois Chicago summarized research on intermittent fasting to provide insights into its effects on the body and to provide advice for incorporating these diets in everyday life.
They have also presented recommendations for future research into these popular diet methods.
The study is published in Nature Reviews Endocrinology and was conducted by Krista Varady et al.
The three main forms of intermittent fasting were reviewed: alternate-day fasting—consuming 0–500 calories on alternating feast days; the 5:2 diet—two fast days and five feast days per week; and time-restricted eating—eating only during a prescribed time window each day.
These diets produce mild to moderate weight loss, 3% to 8% loss from baseline, over short durations of eight to 12 weeks.
The review also states that intermittent fasting is on par with traditional calorie-restricted diets and shows results in improving some cardiometabolic risk factors.
Additionally, intermittent fasting is generally safe, producing few gastrointestinal, neurological, hormonal or metabolic effects.
For example, a recent study from the University of Sydney and published in Cell Reports found how intermittent fasting works on the liver to help prevent disease.
The findings could help medical scientists working in cancer, heart disease, and diabetes research develop new interventions to lower disease risk and discover the optimum intervals for fasting.
In that study, the team examined how every-other-day fasting affected proteins in the liver.
They found an unexpected impact on fatty acid metabolism and the surprising role played by a master regulator protein that controls many biological pathways in the liver and other organs.
In particular, the researchers found that the HNF4-(alpha) protein, which regulates a large number of liver genes, plays a previously unknown role during intermittent fasting.
The researchers also found that every-other-day-fasting—where no food was consumed on alternate days—changed the metabolism of fatty acids in the liver, knowledge that could be applied to improvements in glucose tolerance and the regulation of diabetes.
A technique known as multi-Omics, which considers multiple data sets such as the total collection of proteins and genes, was used in the study.
It allows for the integration of large amounts of information to discover new associations within biological systems.
The team says that the information can now be used in future studies to determine optimum fasting periods to regulate protein response in the liver.
Related: More than a decade of intermittent symptoms, then heart failure.
Other findings from the current review included:
Fasting works for individuals of normal weight as well as those with obesity.
People with insulin resistance or prediabetes benefit from intermittent fasting, losing similar weight amounts as those without those conditions.
Body composition for weight loss during intermittent fasting is similar to calorie-restriction diets, with 75% of the weight lost being fat and 25% lean mass.
The research also dispelled some myths about intermittent fasting.
The main myth is people are going to feel weak and not be able to concentrate during fasting.
Researchers have shown it is the opposite: They actually have a better ability to concentrate. Additionally, current research shows intermittent fasting does not harm metabolism.
For those who want to try intermittent fasting, and for their clinicians, the review offers these guidelines:
Who can do intermittent fasting?
Adolescents with severe obesity. Adults with normal weight, overweight or obesity. Adults with hypertension or high cholesterol. Patients with insulin resistance or prediabetes. Patients with Type 1 or Type 2 diabetes.
Advice for starting intermittent fasting:
Plan on a one- or two-week adjustment to fasting. Headaches are common but can subside with increased water intake.
Boost fiber through eating fruits, vegetables and whole grains.
Eat at least 50 grams of lean protein on the fast days when alternating feast days to control hunger and prevent excessive lean mass loss.
What should be monitored during intermittent fasting?
Adverse effects: Clinicians should assess adverse effects during the first three months of the diet.
Nutrient deficiencies: Clinicians should monitor vitamin and mineral levels.
Medications: Medications to control blood pressure, cholesterol and glucose should be monitored and may need to be reduced if the patient loses weight.
Therapy: Patients should participate in behavioral change programs to help achieve long-term weight management.
If you care about nutrition, please read studies that common eating habit may lead to high blood sugar, weight gain, and why healthy eating can help you fight COVID-19.
For more information about health, please see recent studies that tea may help you lose weight during sleep, and results showing this diet can effectively help you lose weight and reduce cholesterol.
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