Is Being Physically Fit or Fatness More Important for Longevity?

Image of Cathe Friedrich leading a workout during the Glassboro Road Trip. Is Being Physically Fit or Fatness More Important for Longevity?

Being physically fit or fatness – which is most important for health and longevity? Health care professionals would argue that you need to stay as fit as possible AND manage your body weight to avoid obesity to maximize health and longevity. Fitness and leanness sound ideal! But, if you could only choose one – fitness or healthy body weight, which would be your best bet for maximizing longevity?

Being Physically Fit Matters

An interesting study published in the American Medical Association looked at the fitness level and body composition of 2,603 older adults with an average age of just over 64. After measuring their body fat percentage, BMI, and waist size, they asked these healthy individuals to do an exercise treadmill test to determine their aerobic capacity. Then, they followed the participants for 12 years to determine their death rates.

The results?  The participants who scored highest in terms of physical fitness died at less than half the rate of physically unfit subjects. The exceptions were two groups where the participants were significantly obese. The physically fit participants were also less likely to have risk factors for premature death such as elevated blood pressure, diabetes, or lipid abnormalities. Interestingly, obese but fit individuals in the study had lower mortality relative to unfit, older individuals of normal weight.

The study also showed that fit individuals who were obese had a lower risk of all-cause mortality compared to unfit, normal-weight, or lean individuals. This study suggests that having a high fitness level may be more important than reaching an ideal body weight. It also introduced the obesity paradox, the idea that being overweight or even mildly obese may offer some protection against mortality in older individuals as long as they’re physically fit. However, most health care professionals don’t subscribe to the idea that excess body fat is a health benefit. More recent studies show that obese but healthy people, particularly those who aren’t physically fit, are at higher risk of developing metabolic abnormalities later on.

What about Muscle Strength and Longevity?

The previous study used cardiorespiratory fitness, based on performance on a treadmill test, as a marker of physical fitness – but what about muscle strength? A study of more than 400,000 middle-aged and older adults in the United Kingdom looked at muscle function. This study used handgrip strength as a marker of muscle strength. The participants were between the ages of 40 and 69. What they found was men who had the least body fat and were the weakest had the highest all-cause mortality. The guys who had the greatest levels of body fat but scored well on strength testing showed no increased mortality risk and had a death rate similar to men with significantly less body fat.

Another study involving 8,700 men of all ages used a different approach to measuring strength, one you’re probably familiar with, the one-rep max test. The one-rep max test is a measure that fitness trainers use to assess new clients and determine what weight they should use when they begin strength training. To measure your own one-rep max, a fitness trainer would determine the heaviest weight you can lift only one-time using good form. In the study, mortality from all causes was similar between men in the lower third of strength (based on one-rep max test) who had normal body fat relative to those who were overweight and obese but in the top third of muscle strength. As might be expected, the guys who were both strong and not obese had the lowest mortality. But, as this study suggests, being strong may compensate for the risks associated with being mild to moderately overweight or obese.

Why Being Physically Fit Matters

It’s not surprising that fitness has profound implications on mortality. Good cardiovascular fitness reduces the risk of dying of cardiovascular disease, the most common cause of mortality in both men and women in Western countries. When you have good muscles strength, you’re more functional and less likely to injure yourself or fall. Plus, having more muscle is associated with better metabolic health and insulin sensitivity. In addition, strength training to develop greater strength and muscle size helps prevent bone loss. That’s important since hip fractures carry a high risk of mortality and debility.

Just as importantly, these studies show that being strong and physically fit may offset the mortality risks of being obese. Even if an obese individual can’t get down to normal body weight, they can still resistance train and do exercise that gets their heart rate up on a regular basis. Doing so may lower the risk of dying prematurely. This level of fitness is accessible to almost everyone! You don’t have to become a sports superstar to get the health benefits that being physically fit offers. Studies show that even people in their 80’s and 90’s are capable of building strength and improving their fitness level through supervised training. Movement matters!

The Bottom Line

Based on the research, being physically fit is beneficial, regardless of your body size or how much fat you carry on your frame. What’s more, high level of physical fitness, both cardiovascular and strength, may compensate, at least to some degree, for being overweight or obese. However, we can’t ignore the health risks of obesity, particularly severe obesity. Studies show that being obese increases the risk of many health problems. The obvious ones are cardiovascular disease and type 2 diabetes, but studies also show that being obese elevates the risk of 13 types of cancer. Fortunately, staying physically active may compensate for some of this risk as well. Regular physical activity also helps with weight control as well. So, keep working out, irrespective of what the scale says. You’re doing something positive for your mind and your body!



JAMA. 2018;319(3):231-232. doi:10.1001/jama.2017.21649.

Cardiopulmonary Physical Therapy Journal: February 08, 2018 – Volume Publish Ahead of Print – Issue – p .doi: 10.1097/CPT.0000000000000079

Progress in Preventive Medicine: April 2018 – Volume 3 – Issue 2 – p e0013 doi: 10.1097/pp9.000000000000001.

WebMD.com. “Obesity Linked to 13 Types of Cancer”


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