Recently, Dr. Satchin Panda sent me a copy of a fascinating paper he and colleagues have just published in the journal Cell Metabolism. Dr. Panda, who is a loyal Obesity Panacea reader, suggested I share the interesting results of the study with our readers. Instead, I thought it would be more fun to interview Dr. Panda about his research so that he could share his findings directly. Hope you enjoy the interview, and see the bottom of the post for details on Dr. Satchin Panda.
PJ: What was the major finding of your study?
SP: Scientists have long assumed that the cause of diet-induced obesity in mice is nutritional; however, our discovery shows that the spreading of caloric intake through the day may contribute, as well, by perturbing metabolic pathways governed by the circadian clock and nutrient sensors. For decades, our society has focused on calorie in, calorie out, exercise and eat healthy, however, this is a novel study that has shown when we eat could be just as important as what we eat.
PJ: Can you briefly describe how the study was conducted?
SP: We put two groups of mice on different eating regiments for 100 days. Both groups ate a high-fat, high calorie diet. The first group was allowed to eat whenever they wanted, grazing throughout the day and night. The other mice had access to food only for eight hours at night, since mice are nocturnal. The results were astonishing. Despite consuming the same amount of calories everyday, the mice that ate on a restricted eight hours were nearly 40 percent leaner and showed no signs of inflammation or liver disease and had healthy cholesterol and blood sugar levels. The group of mice that nibbled day and night became obese, developed high cholesterol, high blood sugar, fatty liver disease and metabolic problems.
PJ: What is the implication of these findings to the average overweight individual?
SP: Our body is designed to undergo overnight fasting. For millions of years humans ate only during the day time. Only recently in the last 50 years our society began eating more at night, and during longer periods throughout the day. Much like our brain needs to rest at night, our data suggests that the stomach and the body’s digestive system need to rest from processing incoming fuel, otherwise we work our organs into a state of metabolic exhaustion. Imagine trying to perform major construction work on a busy highway in the middle of rush hour traffic? Our stomach and liver repairs itself every night, and consuming more food is similar to putting more cars on the road when repairs are being made. It causes a lot of chaos. Researchers may be overlooking the role that timing has on the body’s response to food.
PJ: What is a major limitation of your findings?
SP: The recent study is only conducted in mice. We dont even have an evidence-based measurement of when people eat or know whether eating too many hours correlates with predisposition to metabolic disease.
PJ: Does your research dispute the notion that many small meals throughout the day are the optimal strategy for weight loss or prevention of weight gain?
SP: Our study in mice suggests that an extended fasting time, allowing your stomach and liver to rest may prevent weight gain and metabolic diseases. It does not dispute the notion, as our mice on 8 h eating were still eating frequently.
PJ: What should be the follow-up study to this one? What remains unclear?
SP: Our research needs to be conducted in humans before we could definitively apply it to fight the obesity and diabetes epidemic. However, this study changes the paradigm of our focus on solely calorie-in and calorie out. It brings the notion that our body’s calorie use efficiency can be substanctially changed by eating pattern alone. The effect in humans is unclear. Wheter fasting can also reduce the harmful impact of high fructose and high carb diet needs to be tested. In mice, whether 10,12,14,16 h eating has similar effect also needs to be explored.
PJ: Thanks so much for sharing this fascinating work with us, Satchin.
Dr. Satchidananda Panda is an Associate Professor in the Regulatory Biology Laboratory at the Salk Institute. His research focuses on the effect of biological clock on behavior physiology and metabolism.
Reference: Hatori et al., Time-Restricted Feeding without Reducing Caloric Intake Prevents Metabolic Diseases in Mice Fed a High-Fat Diet. Cell Metabolism (2012) doi:10.1016/j.cmet.2012.04.019