Obesity not only harms the body, but also the brain?

Obesity, as a complex metabolic disorder, is a major cause of chronic diseases such as diabetes, hypertension, cardiovascular disease and certain types of cancer, and disability.

Recently, research from Australia found that obesity not only affects body shape and increases the risk of major chronic diseases, but harmful fat in the body also increases the risk of dementia.

In other words, [obese people may become stupider faster. ]

Previous studies have shown that being overweight or obese can also significantly reduce blood flow to the brain, and that every 1 cm increase in waist circumference results in a decrease in cerebral blood flow equivalent to that of a person being one year older.

This means that [obese people may have brains that age faster. ]

Obesity has been noted to be associated with changes in brain structure, with the more obese a person is, the less gray matter volume (GMV) they have, even in “healthy obese people.” The brain’s gray matter is responsible for executive control, muscle and sensory activity, as well as learning, attention, and memory.

In this study, researchers investigated the genetic data of 336,309 participants in the UK Biobank and specifically analyzed the brains of three types of obese people: metabolically poor obesity (BMI and waist-to-hip ratio increased simultaneously), metabolically neutral obesity (only BMI increased) and metabolically good obesity (BMI increased, waist-to-hip ratio decreased). The results showed that:

1. People with higher levels of obesity, especially those with dysmetabolic obesity and neutral obesity, have much lower levels of brain gray matter and their brain function may be impaired.

2. For the middle-aged and elderly population (37-73 years old), for every 1kg/m2 increase in BMI, the gray matter volume will decrease by 0.3%, which is equivalent to the impact of a 3kg weight increase on a person with an average height of 173 cm.

3. In contrast, in older adults (mean age 75 years) with mild cognitive impairment or Alzheimer's disease, the same increase in BMI was associated with a 0.5%-1.5% decrease in gray matter volume.

Why does obesity affect the brain?

1. Excessive adipose tissue increases the secretion of pro-inflammatory cytokines that can cross the brain-blood barrier

2. One hypothesis is that inflammation may play a central role in the link between obesity and the brain.

3. The association between poor metabolism and moderate obesity observed in the study was associated with higher levels of C-reactive protein (CRP), a non-specific inflammatory marker.

4. In addition to obesity, it has been found to be elevated in many other diseases, including depression, infections, and inflammatory bowel disease.

These findings may suggest that inflammation plays a role in the link between obesity and reduced gray matter volume.

China is the country with the largest number of obese people. Obesity has become a global epidemic. Two out of every five people are obese.

This study suggests that efforts to control metabolic abnormalities associated with obesity may be beneficial in minimizing the adverse effects of excess fat on the brain.

There is one more reason to lose weight. Let’s go and lose weight. Are you coming?

References

doi.org/10.1016/j.neurobiolaging.2021.02.010

doi.org/10.1016/j.neurobiolaging.2021.04.008