It turns out losing weight when you’re in your 40s, 50s or 60s isn’t such a good idea. A new study out of Boston University has found that trying to shed off excess pounds during middle age was linked with negative health outcomes such as a higher risk of dementia.

Their findings revealed that putting on extra flesh in early middle age and eventually burning them off in late middle age had a strong association with cognitive function and therefore increased one’s vulnerability to cognitive decline.

“If after a steady increase in weight that is common as one gets older, there is an unexpected shift to losing weight post midlife, it might be good to consult with one’s healthcare provider and pinpoint why. There are some potential treatments emerging where early detection might be critical in the effectiveness of any of these treatments as they are approved and become available,” explains the study’s corresponding author, Professor Rhoda Au.

For one, dementia is a growing global public health concern with about 55 million people currently estimated to be living with this disorder. The researchers state the number is more likely to rise dramatically by 2050 worldwide. On the other hand, body mass index BMI is used as a means to calculate obesity which is also a worldwide pandemic and likewise associated with an increased risk for dementia. 

However, the link between body mass index and dementia risk remains a hotly-debated topic. With no cure in sight, this, therefore, moved the researchers from Boston to explore preventive measures that could slow the dementia incidence.

The new study—published in the journal Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association—adds to the growing body of evidence on a gradually declining body weight and dementia association.

Study Methodology

For the study, the researchers looked at data from the Framingham Heart Study (FHS) Offspring Cohort involving over 2,405 non-demented participants between the ages of 30 to 50 years. Participants were interviewed and they underwent both physical examinations and laboratory investigations. Both weights and heights of the participants were taken repeatedly every two to four years to calculate changes in BMI. They then compared these different weight patterns among those who gained or lost weight and those whose weight remained stable for both demented and non-demented individuals.


During an average follow-up period of 39 years, the researchers found that the overall trend of losing body weight was linked to a higher risk of developing dementia. They state that a lack of fluctuations in body weight during middle age may not raise dementia risk. If however, body weight increases during middle age and then shifts course after the age of 50, the person is most likely to develop dementia.

Above all their findings, in line with other studies, further supports the link between stability in body weight and better cognitive trajectories.

The study authors, however, see the need for further studies involving a larger group of people with dementia cases.

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