While it’s normal for the number on the scale to fluctuate when you’re losing weight, if you’re constantly losing and regaining weight (aka yo-yo dieting), you could be increasing your risk of developing dementia, among other health issues. Here, a look at the latest science and how well-balanced eating can play a role in keeping the brain healthy.


The latest research published in BMJ open found older adults who experienced more than a 10% increase or decrease in their body mass index (BMI) over a two-year period had a 20% higher risk of developing dementia than those who had a stable BMI during the same time period. Similarly, other studies have found weight fluctuations of 2.2 pounds per year were linked with a 10% increased dementia risk.

Researchers believe weight gain leading to a higher BMI could increase inflammation, triggering brain changes that lead to dementia. (A separate study implicated inflammation in neurodegeneration in the brain, increasing the risk for cognitive decline).

What’s more, a one-unit drop in BMI was linked to a 25% increased risk of dementia. Here, researchers note that a significant drop in BMI could be a sign of underlying health issues such as cardiovascular disease, cancer, liver or lung disease, which are all associated with declines in cognitive function, including dementia.


“Focusing on nutrient-dense, whole foods could help avoid weight fluctuations that are associated with cognitive decline,” says Heather Snyder, PhD, senior director of medical and scientific operations at the Alzheimer’s Association.

“Currently, there is no definitive prescription for preventing or reducing risk of Alzheimer’s disease and other dementias. However, there is emerging evidence that healthy eating styles like the DASH and Mediterranean diets, which are high in leafy greens, whole grains, lean proteins, like omega-3 rich fish, and low in saturated fats, promote both heart and brain health,” says Snyder.

Moderating your alcohol consumption could also benefit your brain. A 2019 study published in the medical journal JAMA found low-to-moderate alcohol consumption could be protective against cognitive decline, even among those at high genetic risk for developing dementia. The mechanism is unclear but study co-author Elzbieta Kuzma, PhD, a research fellow at the University of Exeter Medical School suspects inflammation could play a role.


“It’s important to bear in mind that our findings do not prove a causal relationship [but] they do carry a very optimistic public health message: Although we can’t change our genes, we can try to reduce our risk of dementia by following a healthy lifestyle,” says Kuzma.