Treading water: mixed effects of high fat diet on mouse behavior in the forced swim test

Diet is an environmental factor with significant potential to affect the brain and behavior in both positive and negative ways. Work in animals is necessary to understand this relationship and how it may apply to mental health in humans. One area which has been investigated extensively is whether diet, specifically a high fat diet (HFD), can alter behavior in tasks, such as the forced swim test (FST) that assess stress coping. Therefore, we sought to analyze the literature regarding the effect of HFD on performance in the FST to determine whether there was a consistent effect of HFD on stress coping behavior. We conducted a Google Scholar search of English-language articles with the following terms: high fat diet, obesity, forced swim test, depression like behavior, mouse. Thirty studies from twenty-five publications are included in this survey. Fifteen studies were found where HFD had no effect on FST, 4 where HFD decreased immobility, and 11 where HFD increased immobility. Experimental details in these studies varied widely, including differences in the diet, mice, and experimental design. Additionally, we analyzed thirteen studies that performed the tail-suspension test (TST) after HFD, with six studies finding no change due to HFD and 7 reporting that HFD increased immobility. Further, 6 of these studies used both FST and TST with largely similar results in the two tasks, indicating concordance between the two tests of stress-coping behavior. We conclude that due to widely varying experimental details across studies no consistent effect of high fat diet on stress coping behavior can be determined at this point.