Longer overnight fasts, Early Breakfasts

A September 2024 study by Barcelona Institute for Global Health (ISGlobal) said,

• "Our results, in line with other recent studies, suggest that extending the overnight fast could help maintain a healthy weight if accompanied by an early dinner and an early breakfast. We think this may be because eating earlier in the day is more in line with circadian rhythms and allows for better calorie burning and appetite regulation, which can help maintain a healthy weight. However, it is too soon to draw definitive conclusions, so recommendations will have to wait for more robust evidence",

• "There are different ways of practising what is known as 'intermittent fasting' and our study relates to one of them, which is overnight fasting. What we observed in a subgroup of men who do intermittent fasting by skipping breakfast is that this practice has no effect on body weight. Other intervention studies in participants with obesity have shown that this tactic is no more effective than reducing calorie intake in reducing body weight in the long term,"

• "Our research is part of an emerging field of research known as 'chrononutrition', which focuses not only on analysing what we eat, but also the times of day and the number of times we eat"

The Fasting-mimicking diet (FMD)

A February 2024 study by the University of Southern California on the Fasting-mimicking diet (FMD) [“a five-day diet high in unsaturated fats and low in overall calories, protein, and carbohydrates and is designed to mimic the effects of a water-only fast while still providing necessary nutrients”] said

“This is the first study to show that a food-based intervention that does not require chronic dietary or other lifestyle changes can make people biologically younger, based on both changes in risk factors for aging and disease and on a validated method developed by the Levine group to assess biological age,”

“This study shows for the first time evidence for biological age reduction from two different clinical trials, accompanied by evidence of rejuvenation of metabolic and immune function,”

“Although many doctors are already recommending the FMD in the United States and Europe, these findings should encourage many more healthcare professionals to recommend FMD cycles to patients with higher than desired levels of disease risk factors as well as to the general population that may be interested in increased function and younger age,”

14 Hour Fasts

A November 2023 study by Kings College London

• “This is the largest study outside of a tightly controlled clinic to show that intermittent fasting can improve your health in a real world setting. What's really exciting is that the findings show that you don’t have to be very restrictive to see positive results. A ten-hour eating window, which was manageable for most people, and improved mood, energy levels and hunger. We found for the first time that those who practised time-restricted eating, but were not consistent day to day, did not have the same positive health effects as those who were dedicated every day. ”  

• “This study adds to the growing body of evidence showing the importance of how you eat. The health impact of food is not just what you eat but the time at which you choose to consume your meals, and eating window is an important dietary behaviour that can be beneficial for health. Findings shows that we don’t need to be eating all the time. Many people will feel satiated and even lose weight if they restrict their food to a ten-hour window.” 

Calorie Restriction; Muscle Rejuvenation

A study in October 2023 by the National Institue of Aging suggests that a reduction in calories may help rejuvenate muscles and active biological systems that promote health.

• "A 12% reduction in calorie intake is very modest,"

• "This kind of small reduction in calorie intake is doable and may make a big difference in your health."
  "Since inflammation and aging are strongly coupled, calorie restriction represents a powerful approach to preventing the pro-inflammatory state that is developed by many older people,"

Dementia and Fasting

A September 2022 study of mice by USC Leonard Davis School of Gerontology and others, found mice on a fasting-mimicking diet [high in unsaturated fats and low in overall calories, protein, and carbohydrates] showed less Alzheimer’s pathology.

Intermittent fasting

A March 2022 study by the University of Illinois Chicago looked at

(1) Alternate-day fasting — consuming 0-500 calories on alternating feast days; 

(2) The 5:2 diet — two fast days and five feast days per week; 

and 

(3) Time-restricted eating — eating only during a prescribed time window each day.

The study said,

• “The main myth is people are going to feel weak and not be able to concentrate during fasting. We’ve shown it is the opposite: They actually have a better ability to concentrate,”

• “With any diet, as you lose weight, your metabolism, like your calorie needs, will go down because they’re correlated tightly with your muscle mass. As you lose weight, people tend to lose a little bit of muscle. But fasting doesn’t tank your metabolism at all. We’ve shown that it is the same that would happen with like traditional dieting,”

Time restricted eating and diabetes

A July 2022 study by NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, the Netherlands said, 

“Mechanisms underlying the improvement in glucose regulation upon TRE [Time Restricted Eating] remain unclear. Our results show that TRE did not improve peripheral and liver insulin sensitivity, skeletal muscle mitochondrial function, energy metabolism or liver fat content, all of which are known to be affected in T2D [Type 2 Diabetes].” 

They concluded,  

“A daytime 10 h TRE regimen for 3 weeks decreases glucose levels and prolongs the time spent in the normal blood sugar range in adults with T2D as compared with spreading daily food intake over at least 14 h. These data highlight the potential benefit of TRE in T2D”

And “Since our TRE protocol was feasible and safe, and resulted in improved 24 h glucose levels, it would be interesting to examine the impact of 10 h TRE on glucose regulation and insulin sensitivity in type 2 diabetes in the long term to address the clinical relevance of TRE.”

The feeding window and obesity

A May 2021 study by the University of Surrey said,

"Time-restricted feeding has the potential to become an extremely effective tool in the fight against the obesity epidemic facing many countries. However, the study clearly shows that the ability of people to restrict their daily feeding window is dependent on their individual lifestyles.”

The study found that most people could reduce their feeding window by 3 hours.

Fasting, blood pressure, gut microbiota

Fasting > gut health > lower blood pressure

An April 2021 study by Baylor College of Medicine said,

"Previous studies from our lab have shown that the composition of the gut microbiota in animal models of hypertension, such as the SHRSP (spontaneously hypertensive stroke-prone rat) model, is different from that in animals with normal blood pressure,"

"This result told us that gut dysbiosis is not just a consequence of hypertension, but is actually involved in causing it," 

"This ground work led to the current study in which we proposed to answer two questions. First, can we manipulate the dysbiotic microbiota to either prevent or relieve hypertension? Second, how are the gut microbes influencing the animal's blood pressure?"

"Next, we investigated whether the microbiota was involved in the reduction of blood pressure we observed in the SHRSP rats that had fasted,"

"It was particularly interesting to see that the germ-free rats that received microbiota from the fasting SHRSP rats had significantly lower the blood pressure than the rats that had received microbiota from SHRSP control rats,”

"These results demonstrated that the alterations to the microbiota induced by fasting were sufficient to mediate the blood pressure-lowering effect of intermitting fasting.”

"We applied whole genome shotgun sequence analysis of the microbiota as well as untargeted metabolomics analysis of plasma and gastrointestinal luminal content. Among the changes we observed, alterations in products of bile acid metabolism stood out as potential mediators of blood pressure regulation,"

"Supporting this finding, we found that supplementing animals with cholic acid, a primary bile acid, also significantly reduced blood pressure in the SHRSP model of hypertension," 

"This study is important to understand that fasting can have its effects on the host through microbiota manipulation," 

"This is an attractive idea because it can potentially have clinical applications. Many of the bacteria in the gut microbiota are involved in the production of compounds that have been shown to have beneficial effects as they make it into the circulation and contribute to the regulation of the host's physiology. Fasting schedules could one day help regulate the activity of gut microbial populations to naturally provide health benefits."

Intermittent Fasting and Belly Fat

A March 2021 study by the University of Sydney on mice found that, 

• "While most people would think that all fat tissue is the same, in fact, the location makes a big difference,"

• "Our data show both visceral and subcutaneous fat undergo dramatic changes during intermittent fasting,"

• "visceral [belly] fat can adapt to repeated fasting bouts and protect its energy store,"

• "This type of adaptation may be the reason why visceral fat can be resistant to weight loss after long periods of dieting."

The feeding window and obesity

A May 2021 study by the University of Surrey said,

"Time-restricted feeding has the potential to become an extremely effective tool in the fight against the obesity epidemic facing many countries. However, the study clearly shows that the ability of people to restrict their daily feeding window is dependent on their individual lifestyles.”

The study found that most people could reduce their feeding window by 3 hours.

Psoriasis and the 5:2 diet

A May 2021 study by Ghent University, Belgium said,

"We had observed positive results in mice with gut inflammation and psoriasis, with inflammation in the gut driving cutaneous symptoms," 

"Through scientific curiosity and my own experience with fasting as a Muslim, I wanted to find out whether dietary intervention would have the same effects on human patients with psoriasis.”

"The effect of dietary interventions on skin health is a stimulating field of research in dermatology. The results of this study add to the growing body of evidence being undertaken to understand the relationship between the gut and skin, with some promising results for patients and the disease management of psoriasis." Said University Hospital of La Timone, Marseille.

Fasting then a Healthy Diet

A March 2021 study by the Center for Molecular Medicine in the Helmholtz Association and the Experimental and Clinical Research Center run by the Charité Universitätsmedizin Berlin found that, 

"Switching to a healthy diet has a positive effect on blood pressure," 

"If the diet is preceded by a fast, this effect is intensified." 

"The innate immune system remains stable during the fast, whereas the adaptive immune system shuts down," 

"Body mass index, blood pressure and the need for antihypertensive medication remained lower in the long term among volunteers who started the healthy diet with a five-day fast," 

"We were able to isolate the influence of the medication and observe that whether someone responds well to a change of diet or not depends on the individual immune response and the gut microbiome," 

"Those who have [low healthy gut bacteria] often feel that it is not worth the effort and go back to their old habits," 

"Fasting acts as a catalyst for protective microorganisms in the gut. Health clearly improves very quickly and patients can cut back on their medication or even often stop taking tablets altogether."

Diabetes, Fasting in Ramadan

A March 2020 study by the University of California of a protocol called “Fasting Algorithm for Singaporeans with Type 2 Diabetes” (FAST) found greater improvements in glycemic control of fasting adults with type 2 diabetes for that “those who managed their condition in collaboration with their health care provider using [the protocol].”

Low carbohydrate diets are also something which should be considered.

Diabetes, Liver Fibrosis, and Fasting

February 2020 studies by Yale University found a link between diabetes and fasting and liver fibrosis and fasting.   The link concerns two proteins* that are connected to blood glucose production in the liver.

*Tet methylcytosine dioxygenase 3 (TET3) and Hepatocyte Nuclear Factor 4 (HNF4)

Weight Loss Using Different Diets and Fasting

A January 2020 study by the University of Otago found that for some, certain types of diet and fasting can be, “healthful, beneficial ways to eat". The researchers said, “This work supports the idea that there isn't a single 'right' diet - there are a range of options that may suit different people and be effective. In this study, people were given dietary guidelines at the start and then continued with their diets in the real world while living normally. About half of the participants were still following their diets after a year and had experienced improvements in markers of health.”

"Like the Mediterranean diet, intermittent fasting and paleo diets can also be valid healthy eating approaches - the best diet is the one that includes healthy foods and suits the individual."

“Our participants could follow the [Mediterranean] diet's guidelines more closely than the fasting and paleo diets and were more likely to stay with it after the year, as our retention rates showed."

Intermittent Fasting for Metabolic Syndrome

A November 2017 study by the University of California, San Diego found that,

“There is a critical window for intervention with metabolic syndrome. Once people become diabetic or are on multiple medications, such as insulin, it's very hard to reverse the disease process.

"Metabolism is closely linked with circadian rhythms, and knowing this, we were able to develop an intervention to help patients with metabolic syndrome without decreasing calories or increasing physical exercise."

"Time-restricted eating is a simple dietary intervention to incorporate, and we found that participants were able to keep the eating schedule,"

"Eating and drinking everything (except water) during a 10-hour window allows your body to rest and restore for 14 hours at night. Your body can also anticipate when you will eat, so it can prepare the body to optimize metabolism."

"Knowing how to optimize circadian rhythms could lead to a new treatment option for metabolic syndrome patients with life-altering diseases."

Optimizing Your Intermittent Fasting: the Evidence Base

A 2018 study found that, “Early Time-Restricted Feeding ETRF improves insulin sensitivity, blood pressure, and oxidative stress.”

A 2018 systematic review concluded that, “Intermittent energy restriction may be an effective strategy for the treatment of overweight and obesity. Intermittent energy restriction was comparable to continuous energy restriction for short term weight loss in overweight and obese adults. Intermittent energy restriction was shown to be more effective than no treatment, however, this should be interpreted cautiously due to the small number of studies and future research is warranted to confirm the findings of this review.”

An Experiment

You may like to try an “early day” intermittent fasting by eating between 7am and 3 pm, or 10am and 6pm, and avoid eating in the evening before bed.

Studies and Reviews

1.     Sutton, E.F, Bey, R., Early, K., Cefalu, W.T, Ravussin, E. and Peterson C.M. (2018) Early Time-Restricted Feeding Improves Insulin Sensitivity, Blood Pressure, and Oxidative Stress Even without Weight Loss in Men with Prediabetes. Cell Metabolism, Volume 27, Issue 6, 5 June 2018, Pages 1159-1160

2.     Harris, L, Hamilton, S., Azevedo, L., Olajide, J.,De Brun, C.,Waller, G.,Whittaker, V.,Sharp, T.,Lean, M.,Hankey, K. and Ells, L. (2018) Intermittent fasting interventions for treatment of overweight and obesity in adults: a systematic review and meta-analysis. BI Database of Systematic Reviews and Implementation Reports: February 2018 - Volume 16 - Issue 2 - p 507–547. doi: 10.11124/JBISRIR-2016-003248