Obesity is extremely prevalent in the U.S. population and can lead to a variety of health complications, such as high blood pressure, endothelial dysfunction, inflammation and even chronic kidney disease.
Intermittent fasting—referred to as “time-restricted feeding” in research—is a popular diet in which food is only eaten between certain hours (sometimes called an “eating window”). One recurring question about this kind of diet is if it can actually minimize the adverse health effects of obesity. Claudia Edell, a PhD candidate at the University of Alabama at Birmingham, presented her research examining the effects of time-restricted feeding on kidney inflammation in obesity at the American Physiology Summit in Long Beach, California, last month.
T cells are a type of white blood cell that play a key role in inflammation. There are two main classifications of T cells: CD4+ and CD8+. CD4+ T cells are often classified as “helpers,” while CD8+ T cells are damaging to cells (cytotoxic). Edell and her colleagues examined the presence of C8+ cells in the kidney in a mouse model of obesity. Some of the mice that were on a high-fat diet during the trial were put on a time-restricted feeding diet for two weeks in which they did not eat during their inactive or sleeping period during the day. But, during their active period at night, the mice were given access to high-fat food for 12 hours.
When the mice ate the high-fat diet, they had significantly more of the cytotoxic CD8+ T cells in their kidneys, which may be a contributing factor to the kidney damage often seen in people with obesity. However, after the time-restricted feeding, the kidneys had much less fibrosis, or scarring, and fewer cytotoxic CD8+ T cells than the obese mice who had access to food at all times. Interestingly, this increased concentration of T cells is seen at night in the active phase of the mice but not during the day when they aren’t active. These changes in T cells are also not seen in the circulating blood but are localized to the kidneys.
While future research is needed to find out where these T cells come from, or if they are expanding in the kidney, this exciting research indicates that when you eat may be just as important as what you eat when it comes to your health.
Gillian Kelly is a PhD student in the Department of Medicine, Division of Nephrology, at the University of Alabama at Birmingham. Her research primarily focuses on early-life stress and the cardiovascular system. Kelly served as a meeting blogger for the 2023 American Physiology Summit.