How Does BMI Affect Protein Intake for Senior Citizens?

Senior citizens are already recommended to consume slightly more protein per pound, but what is driving that decision and how is BMI related to that?

Two of the factors that go into the optimal protein intake are age and weight. Your weight health can be estimated using a BMI calculator, but a tool like this is not always built specifically for senior citizens.

BMI can be a controversial statistic, and though it is a valuable tool – it should be used with a grain of salt when determining your optimal health. It’s important to evaulate special considerations as it pertains to senior citizens, BMI, and optimal protein intake.

Calculating BMI

Use this handy calculator from The Wellness Way to understand your current BMI number:

Once you have that number, you can start to understand where you are and where you are going.

Battling Sarcopenia

As we age, we tend to lose muscle mass – which is called Sarcopenia. We also tend to have a higher degree of fat accumulation, or adiposity.

If we replace lean body mass with fat mass, but our BMI stays the same, is that really a good indication of our weight health? Usually the answer is no, and Sarcopenia complicates the meaning of BMI. Furthermore, BMI alone is not a good indicator of probable sarcopenia.

Do Senior Citizens Have More Fat Mass?

The typical multiplier for protein intake is a wide ranging number depending on who you ask and what your goals are. We are typically looking at .6 to 1 grams of protein per kg for optimal intake. For senior citizens, protein calculators usually recommend closer to 1.2 grams per kg (or .54 grams per pound).

However the key words here are “per pound.”

This is because even though we can use these numbers as a baseline approach to protein intake, we should really be looking at protein intake as it is compared to muscle mass as opposed to overall mass; or more scientifically: appendicular lean mass index (ALMI) as opposed to fat mass index (FMI)

Since senior citizens’ FMI tends to increase while ALMI tends to decrease, it’s important to bump up the grams per pound in protein intake to reflect this change, which is why that number has been determined to be higher by some health organizations.

Understanding the Difference Between BMI, FMI, and ALMI

BMI (Body Mass Index)

A general measure of body weight in relation to height, used to categorize individuals as underweight, normal weight, overweight, or obese. BMI doesn’t differentiate between fat and muscle, but for seniors, a higher BMI may indicate the need for increased protein intake to preserve muscle mass.

FMI (Fat Mass Index)

A measurement that adjusts your body fat in relation to your height, providing a clearer picture of how much of your weight comes from fat. In seniors, a slightly higher fat mass can provide energy reserves and help protect against malnutrition, making balanced protein intake essential to preserve muscle while maintaining healthy fat levels.

ALMI (Appendicular Lean Mass Index)

This metric measures the amount of muscle in your arms and legs relative to your height, helping assess muscle mass and strength, particularly important for evaluating sarcopenia in older adults. Seniors with a lower ALMI often require more protein to help rebuild and maintain muscle mass, crucial for preventing frailty.

A DXA Scan can help you get more accurate data

For seniors especially, it can be extremely beneficial to get the most accurate numbers when calculating BMI, FMI, and ALMI. A DXA (Dual-energy X-ray Absorptiometry) scan can help you do that.

A DXA scan, while commonly known as a bone density test, provides much more than just information about your bone health. In addition to measuring bone strength and mineral content, it offers a detailed breakdown of your body composition, including your Body Mass Index (BMI), Fat Mass Index (FMI), and Appendicular Lean Mass Index (ALMI).

These measurements help assess fat and muscle distribution, giving a more complete picture of your overall health. Providers use DXA scans not only to screen for conditions like osteoporosis and osteopenia but also to evaluate muscle and fat composition, making it a versatile tool for tracking age-related changes in the body.

• Total body bone mineral density
• Total muscle mass
• Total fat mass
• Overall bone mass
• Body fat percentage
• Muscle and fat distribution in the trunk
• Muscle and fat distribution in each arm
• Muscle and fat distribution in each leg
• Measurement of central abdominal fat

Slightly Higher BMI Levels are Good for Senior Citizens

There may be an evolutionary reason why seniors tend to have little more fat mass than other age groups. One of those reasons is that having a higher BMI can help protect against various nutrient deficiencies, including osteoporosis.

What do the data say?

When we break it down, there have been multiple studies, such as this publication from BMJ journals, where the healthiest BMI range for both men and women was 25-29, or slightly overweight. A BMI lower than 25 was less healthy than a BMI of 30-32 for older individuals. It seems that there are very few risks to being slightly overweight, and even moderately obese women had a lower mortality rate.

BMI is not as reliable for older adults

For older adults, a BMI calculation might not be as useful or tell the whole story as it pertains to a healthy weight. According to Colleen Christmas, an MD at John Hopkins, BMI was also established for people with European ancestry; meaning that neither age nor race is a part of the many of the calculators that are out there.

For this reason, losing weight, (and by defacto lowering your BMI) may not always be the healthiest path forward for Senior Citizens.

Senior citizens should have access to more knowledge when it comes to their BMI, including a more precise answer as to their FMI and ALMI. This could better help determine overall nutrition needs and recommendations at the individual level.