BMI (body mass index) is a key sign of overall health. Guidelines recommend that all adults keep their BMI between 18 and 24.9. A BMI of 25 and over indicates that you are overweight. And a BMI over 30 is considered obesity.
However, it is possible that a few extra pounds may not be as harmful to those over age 65 as they are for younger people. In fact, being underweight is something older people should avoid.
This article will discuss healthy weight ranges and BMI for older adults. It will also help you learn how BMI affects older adults and why it's dangerous for older adults to be underweight.
Body Mass Index (BMI) is a dated, flawed measure. It does not take into account factors such as body composition, ethnicity, sex, race, and age.
Even though it is a biased measure, BMI is still widely used in the medical community because it’s an inexpensive and quick way to analyze a person’s potential health status and outcomes.
Verywell / Ellen Lindner
How BMI Affects Older Adults
BMI is calculated by dividing your weight in kilograms by your height in meters squared. There are also plenty of online calculators and charts that can help you determine your BMI based on inches and pounds if you prefer.
There are certain risks associated with having a high BMI at any age. These include heart disease, high blood pressure, diabetes, and stroke.
But a low BMI is also unhealthy, especially for older adults. This has led some experts—including the National Institutes of Health—to suggest that it may be a good idea for older adults to keep a BMI between 25 and 27.
Dangers of Low Body Weight
One of the largest studies that set out to determine just how much BMI affects the health of older adults was published in 2014 in the American Journal of Clinical Nutrition. Researchers combined BMI data from 32 previous studies. The analysis included 197,940 adult participants (all older than age 65) who were followed for at least five years.
The researchers concluded that there was a higher risk of death when BMI was below 23 or above 33.
If you are an older adult, being underweight increases the risk of death.
Several studies have found that being underweight at age 65 was linked to poor health and shorter life expectancy. Being overweight or obese at 65 was only rarely linked to worse health outcomes or lower life expectancy compared to those who were at a healthy weight at age 65.
Sometimes, in fact, the overweight and obese study participants had better health outcomes.
- A Korean study collected data based on interviews with 542 people who had an average age of 74. Scientists discovered that health-related quality of life factors, such as social functioning, emotional health, and pain, are not made worse by a higher BMI in older adults.
- Additional research suggests that older adults who do not have a low BMI enjoy more independence. In fact, a study published in the Archives of Gerontology and Geriatrics found that older adults with BMIs over 30 did not experience a decline in activities of daily living.
Despite this evidence, it does not mean older adults should become overweight or obese on purpose. Being overweight is linked to serious health problems that require ongoing medical treatment and interfere with independence.
Health Risks and Challenges
Being overweight or being underweight is a risk factor for several health conditions. Often, medical illnesses can lead to weight loss or weight gain—or they can make it harder to reach a healthy BMI.
Risks of Being Overweight
Many of the illnesses that can be caused or worsened due to high BMI develop over years.
Some of the conditions that obesity contributes to include:
- Heart disease
- High blood pressure
- Diabetes
- Gallbladder disease
- Osteoarthritis
- Stroke
- Breathing disorders such as sleep apnea
Sometimes a chronic disease can make it harder to have a healthy weight. For example, if your heart disease makes you short of breath when you walk, you may be less active, and you can have a hard time losing weight.
Risks of Being Underweight
Being underweight increases the risk of developing health problems, including nutritional deficiencies that cause medical problems—such as osteoporosis and anemia.
And a low BMI decreases your chances of recovering from illnesses and infections. For example, underweight stroke survivors have worse outcomes than stroke survivors who are overweight or average weight.
You can inadvertently lose weight if you have a chronic disorder that is associated with poor nutrition. Many conditions, such as cancer, gastrointestinal disease, and neurological disease can prevent older adults from eating or absorbing nutrients. This may lead to a low BMI, often for the first time in their lives.
There are no official recommendations on what the ideal weight range or BMI should be for people over 65. Experts recommend that every effort should be made to ensure older adults don't lose weight as a result of illness or poor nutrition.
Scientific data doesn't tell us what the ideal weight patterns are for a long life. But we do know from studying people who live to 100 that being a healthy weight seems to be an important part of living a long life.
Weight Maintenance Goals
When trying to stay healthy, you should work with your doctor to set the right goal for you. Despite what charts and calculators may say, the target BMI is not the same for everyone. You may need to factor in additional considerations.
If you have diabetes, for example, your doctor may recommend that you lose weight. But your doctor may ask you to try to eat more of certain foods if you have anemia.
As you get older, some situations make it more challenging to reach your target BMI.
These factors include:
- Health issues
- Changes in activity level
- Medications
- Metabolism changes
As you face these challenges, you may need the help of a nutritionist. A nutritionist can guide you as you set your calorie goals. Nutritionists can also help you decide whether you need to take vitamin and mineral supplements.
If you lose too many pounds, it may be a sign that you have a health issue that your doctor needs to investigate. It's important to take early action if you become underweight.
How Older Adults Can Gain Weight
- Add foods with a high calorie-to-volume ratio into the diet, including nuts, nut butters, avocados, dried fruit, whole grains, pasta, chocolate, cheese, and full-fat dairy.
- Eat five to six smaller meals per day rather than the traditional three.
- Make sure you eat 1 gram of protein per day for each kilogram of body weight.
- Drizzle extra virgin olive oil over food. It delivers 887 calories per 100 grams.
- Prepare high-calorie meals, such as casseroles, in bulk quantities so that they are always on hand.
- Speak to your doctor about any nutritional supplements you may need.
Summary
Your BMI is one of the indicators of your overall health. Doctors recommend most adults keep their BMI between 18 and 24.9. Adults with a BMI over 25 are considered obese.
On the other hand, older adults do better if they have a BMI between 25 and 27. Research shows that adults over 65 who are underweight experience more health issues and shorter life expectancy.
A licensed nutritionist can help you determine the best diet plan for your health. They can also help you select vitamins and mineral supplements to improve your nutrition.
A Word From Verywell
Trying to keep a healthy BMI can be challenging. Some people struggle with being underweight, while others battle against being overweight. If you are an older adult and find that you are having problems keeping a healthy weight, talk to your doctor or nutritionist. They can provide you with the tools you need to eat the diet that's best for your body and unique situation.
Frequently Asked Questions
What does waist circumference mean for your health?
A person's waist circumference may be able to predict the risk of certain health conditions that occur later in life. For example, when more fat accumulates in the waist instead of the hips, it can signal a higher risk of experiencing heart disease and type 2 diabetes. These risks are heightened in women with a waist size larger than 35 inches and in men with a waist size larger than 40 inches.
Why does cancer cause weight loss?
Cancer can cause weight loss for a few reasons. Loss of appetite, fatigue, decreased skeletal muscle, and a heightened metabolism are all common symptoms in cancer. Some cancer treatments can also lead to appetite loss by causing nausea, vomiting, loss of taste, and difficulty chewing and swallowing.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Mark Stibich, PhD
Mark Stibich, PhD, FIDSA, is a behavior change expert with experience helping
individuals make lasting lifestyle improvements.
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