The Impact of a High-Fat Diet on Your Brain

Everyone craves a bit of ice cream or chocolate now and then when they’re anxious or sad. But a new study suggests that chronic intake of these foods may not only increase anxiety and depression but may also accelerate Alzheimer’s disease.The study -- done in South Africa by neuroscientists Professor Xin-Fu Zhou and Associate Professor Larisa Bobrovskaya -- reveals a direct link between a high-fat diet and an increase in diabetes, as well as a decline in cognitive abilities, such as the development of anxiety, depression, and worsening Alzheimer’s disease. Excessive weight gain was also noted in the subjects with altered cognitive function related to poor metabolism from changes in the brain.This study was published in Metabolic Brain Disease.Associate Professor and UniSA neuroscientist and biochemist Larisa Bobrovskaya notes that the research validates previous research which connected chronic obesity and diabetes with Alzheimer’s disease, which is predicted to increase to 100 million cases by 2050.Bobrovskaya notes, "Obesity and diabetes impair the central nervous system, exacerbating psychiatric disorders and cognitive decline. We demonstrated this in our study with mice."The researchers randomly assigned the mice to standard chow or a high-fat diet for 30 weeks beginning when the mice were 8 weeks old. Food consumption, body weight, and levels of glucose were evaluated at different times. The mice were also given glucose and insulin tolerance tests and checked for cognitive dysfunction. Not surprisingly, the mice fed a high-fat diet gained significant weight, developed insulin resistance, and began behaving abnormally compared to mice fed a standard diet. When fed a high-fat diet, mice with genetically modified Alzheimer’s disease show a bigger decline in cognition and pathological changes in the brain. In individuals with obesity, there is a 55% increase risk for the development of depression. In individuals with obesity and diabetes, that risk is doubled, according to Bobrovskaya.The authors emphasize the importance of treating the global obesity epidemic as a combination of age, obesity, and diabetes. This epidemic may very likely result in a decline in cognitive abilities, Alzheimer’s disease, and additional mental illness diagnoses. Here's how to help your clients who are dealing with obesity and diabetes:

1. Encourage small changes in weight. Even a 5 to 7% reduction in weight may improve blood sugar.
2. Consider intermittent fasting (IF) for weight loss and blood sugar management. Research suggests IF may protect the brain in several ways. 2
3. Adopt an exercise program to aid in weight management, blood sugar control, and reduced risk of depression and mental health conditions.
4. Treat obesity as a chronic disease that needs consistent management. Discourage the use of fad diets when possible.
5. Refer patients to mental health professionals if overeating is preventing weight loss.

By Lisa Andrews, MEd, RD, LDReferences:

1. Jing Xiong, Isaac Deng, Sally Kelliny, Liying Lin, Larisa Bobrovskaya, Xin-Fu Zhou. Long term high fat diet induces metabolic disorders and aggravates behavioral disorders and cognitive deficits in MAPT P301L transgenic mice. Metabolic Brain Disease, 2022; DOI: 10.1007/s11011-022-01029-x
2. Shin BK, Kang S, Kim DS, Park S. Intermittent fasting protects against the deterioration of cognitive function, energy metabolism and dyslipidemia in Alzheimer's disease-induced estrogen deficient rats. Exp Biol Med (Maywood). 2018 Feb;243(4):334-343. doi: 10.1177/1535370217751610. Epub 2018 Jan 7. PMID: 29307281; PMCID: PMC6022926.