Being aerobically fit is a key feature of good health. Not only does physical fitness protect against heart disease, diabetes, dementia and some cancers, it also burns calories helping with weight control.
Most people who are overweight are also unfit. There are, however, a small proportion of people who are classified on the basis of their body mass index (weight divided by height squared) as being both overweight and fit.
Several studies have suggested that being fat and fit is just as healthy has being lean and unfit. This debate has been quashed with the release of data from 1.3 million men in Sweden.
Sweden maintained compulsory military conscription for 18 year old men from 1969 to 1996, during which time over 1.3 million young men were called up to serve their country. Each was given a series of standard fitness tests, including a cycling test to exhaustion.
For an average of 29 years after this test, medical records were reviewed to investigate health and death rates. The fittest 20% of the conscripts had the lowest rate of ill-health and death. The least fit 20% had a 50% greater risk of dying prematurely, most commonly from alcohol and narcotic related deaths.
The researchers examined the death rates in the small number of overweight and obese men who performed well on the fitness test.
For these men there was no health benefit. An unfit and lean man had a better chance of surviving than a fit, obese man.
Fitness is important for health but it can’t undo the health risks associated with excess body fat. Obesity is a significant health burden that needs to be carefully managed.
Improving fitness through regular exercise is important in helping to improve health but other lifestyle strategies are required to help maintain a healthy body weight.