A study by Johns Hopkins Medicine and the NIH’s National Institute on Aging in 40 older adults with obesity and insulin resistance found that both intermittent fasting and a healthy USDA-approved diet improved brain function and metabolic health, with intermittent fasting showing slightly better results in terms of cognitive improvements.
Recent research reveals that intermittent fasting and a standard healthy diet both improve brain function in obese adults with insulin resistance, with intermittent fasting producing better cognitive gains.
Researchers from Johns Hopkins Medicine and the National Institute on Aging at the University of California, San Francisco National Institutes of Health report the results of their study involving 40 elderly people suffering from obesity and insulin Resistance. Participants were randomly assigned to follow either an intermittent fasting diet or a standard healthy eating plan approved by the United States Department of Agriculture (USDA). The study provides important information about the potential benefits of both dietary approaches for brain health.
Insulin resistance is a hallmark of type 2 diabetes and is common in obese people. Studies suggest that people with insulin resistance are at higher risk than usual of developing Alzheimer diseases and other cognitive disorders. Therefore, various weight loss diets are widely used as ways to reduce the risk of these metabolic and brain disorders.
Results and methodology of the study
Previous research from Johns Hopkins University in animal models of diabetes and Alzheimer’s disease has shown that intermittent fasting can improve cognition and insulin sensitivity. The new study, published June 19 in Cellular metabolismtested the effects of intermittent fasting on women and men at risk for cognitive impairment, and proposes a “model,” the authors write, for using a broad panel of biomarkers to assess dietary impact, including analysis of extracellular vesicles — tiny packets of material released by neurons, which are types of brain cells that send messages. These neuron-derived extracellular vesicles are released into the circulating bloodstream and were collected from participants in the new study over an eight-week period, while each person followed one of two diets.
The results revealed that both types of diets had benefits in terms of decreasing insulin resistance and improving cognition, with improvements in memory and executive function with both diets, but more strongly with the intermittent fasting diet, says Mark Mattson, Ph.D., assistant professor of neuroscience at the Johns Hopkins University School of Medicine and former chief of the neuroscience laboratory at the National Institute on Aging in Baltimore. “Other scientists may want to incorporate the (brain) markers (we used) into additional, larger studies of diet and brain health,” Mattson says.
Research techniques and participant demographics
Because people with obesity and insulin resistance may be at greater risk for cognitive impairment and Alzheimer’s disease than people with normal metabolism and body mass index (BMI), Dimitrios Kapogiannis, MD , chief of the section of human neuroscience at the National Institute on Aging and assistant associate professor of neurology at Johns Hopkins University School of Medicine, developed a method to isolate neuron-derived extracellular vesicles from blood. His lab found molecular evidence of insulin resistance in the extracellular vesicles shed by the neurons of people with diabetes and Alzheimer’s disease, and because blood samples are relatively easy to collect, they were considered good candidates for widespread use.
To test the effects of the two diets on biomarkers of brain function, participants in the new study were recruited between June 2015 and December 2022, and four in-person assessments were conducted at facilities run by the National Institute on Brain Function. aging at MedStar Harbor Hospital in Baltimore. . Of the participants, 40 completed their eight-week study. Additionally, 20 people were put on an intermittent fasting diet restricting calories to one-quarter of the recommended daily intake for two consecutive days per week, and they followed the USDA Healthy Eating Diet, which consisted of fruits, vegetables, whole grains and lean proteins. , low-fat dairy and limited added sugars, saturated fat and sodium – for the remaining five days. The USDA healthy eating plan was assigned to 20 other study participants each day of the week.
The average age of participants in both groups was 63, and 25 were white, 14 were black, and one was Hispanic. There were 24 men and 16 women. All were obese and had insulin resistance.
The researchers found that both diets had similarly positive effects on reducing markers of insulin resistance in extracellular vesicles, improving BrainAGE (a measure of the brain’s biological age using structural MRI data), and decreasing brain glucose concentration. A reduced glucose concentration is a corollary of higher glucose consumption.
Both diets also improved common measures of metabolic health, including weight, BMI, waist circumference measurement, blood lipids such as cholesterol and insulin resistance. Executive function and memory (which is a set of mental skills that help with planning and achieving goals) improved about 20% more in the intermittent fasting group than in the healthy diet group.
Health observations and precautions
A few study participants reported modest side effects, including constipation, loose stools, and occasional headaches.
The researchers also found increased levels of a neurofilament protein (a structural protein of neurons) in both diet groups, but primarily in the intermittent fasting group. What this means in terms of brain health is unclear.
“This is a marker that we should continue to evaluate in other studies,” Mattson says. “Neurons release a lot of proteins, and one idea is that intermittent fasting might cause some kind of neuroplasticity (a change in structure) in neurons, causing the release of neurofilament proteins.”
Johns Hopkins researchers and others caution that people interested in intermittent fasting should plan carefully with a health care professional, as it could be harmful for some people, including those with type 1 diabetes and eating disorders.
The research was funded by the National Institute on Aging of the National Institutes of Health (ZIAAG000966, ZIAAG000975).
