Convincing Evidence Shows a Healthy Weight Equals a Healthy Brain


A World Health Organization study has shown that in almost six out of seven countries studied, the happy problem of over-abundant food supplies is resulting in a not-so-happy other problem: obesity.

Obesity is a known risk factor in a plethora of health problems. It plays a role in:

  • Diabetes
  • Heart disease
  • Stroke
  • Cancer (esophageal, pancreatic, colon and rectal, breast, kidney, thyroid, gall bladder, others)

Obesity and Longevity

A study by the National Cancer Institute showed that statistically people with a Body Mass Index (BMI) of 55 to 59.9 lost almost fourteen years off their lives on average. Those with a BMI of 50 to 54.9 lost almost ten years off their lives. Those with BMI of 45 to 49.9 lost an average of 8.9 years.

People who smoke but have normal weight also lose about 8.9 years of life. So, being very obese (BMI of 40 or more) is as threatening to a longer life as cigarette smoking.

Obesity is defined as having a BMI of 30 or more, so the large loss of years of life impacts those who were higher on the obesity scale more than those on the lower side of the scale.

Obesity and Dementia/Alzheimer’s Disease

Even the mildly obese should not necessarily breathe easier. The National Institute on Aging found that dementia and Alzheimer’s have earlier onset rates in people who are obese. A mere unit increase in BMI (one point) at age 50 was related to a seven month earlier onset of Alzheimer’s disease. Those who are on the higher end of the BMI scale may develop these diseases a full ten years before they would have if they had maintained a healthy weight.

The researchers found that the higher a person’s BMI during midlife, the greater the levels of “neurofibrillary tangles” and the protein that fragments into brain plaque, thus impeding brain function. Therefore, BMI and dementia and Alzheimer’s are not only concerns for seniors. Middle-aged people can engage in preventive measures and stave off these neuro-degenerative diseases by staying within the healthiest range of BMI.

Calculating BMI

Using a calculator (or pencil and paper for those who are adept at math), BMI can be calculated by the following formula:

BMI = weight in pounds x 703 divided by height in inches squared.

For example, a woman weighting 154 points who is 5 feet, 6 inches tall would have a BMI of:

BMI = 108262 divided by 4356 (66 inches squared) = 24.85.

This person is within the healthy BMI range.

For the math-challenged, BMI can be calculated by entering one’s height and weight on an online calculator, which may be found at the website of the National Institutes of Health at

The healthiest BMI for adults is 18.5 – 24.9.

A BMI of 25 to 29.9 means a person is overweight.

A BMI of 30 to 39 means a person is obese.

A BMI of 40 or more is very obese.

Obesity Is Rampant

Sharon Begley quotes The National Center for Health Statistics that 36% of American adults are obese. The numbers are climbing, and in ensuing decades it is likely that half of all American adults will be obese. Most developing countries share this problem, as well.

Unless those in well-fed countries learn to restrict their calorie intake, the increasing number of people with earlier-onset dementia and Alzheimer’s will increase exponentially. This will overwhelm health care systems, caregivers, and cost obese persons a great deal of quality of life.


“Adults obese or overweight at midlife may be at risk for earlier onset of Alzheimer’s Disease.” National Institute on Aging, National Institutes of Health, U.S. Department of Health and Human Services, September 1, 2015. Available online at:

Begley, Sharon. “Being Extremely Obese Is Worse For You Than Smoking.” Business Insider, July 8, 2014. Available online at:

BMI Calculator. National Heart, Lung, and Blood Institute, National Institutes of Health, U.S. Department of Health and Human Services. Available online at

Knapton, Sarah, Science Editor. “Britain’s obesity epidemic fuelled by sheer abundance of food.” The Telegraph, June 30, 2015. Available online at:

Obesity and Cancer Risk, National Cancer Institute. Information available online at: