Physical fitness ‘more important than weight loss’ for longer life

By Lilian Anekwe

BMJ Group News

What do we know already?

We know that being physically inactive and not doing any exercise can have lots of negative effects on health. It can lead to weight gain, which can put people at higher risk of conditions like heart attacks and stroke. But we’re not sure of the relative contributions that losing weight and overall fitness make to how long someone lives. Is it better to focus on improving your physical fitness, or concentrate more on losing weight?

To find out, researchers looked at the changes in the fitness and weight of 14,345 men over an average of about six years. They measured physical fitness using a test called the metabolic equivalent of task (MET) and recorded the men’s weight in relation to their height (their body mass index, or BMI) on at least two occasions. They then looked at different groups of men, according to whether their BMI and physical fitness had decreased, stayed the same, or increased, and recorded who died over about 11 years of follow-up.

What does the new study say?

Over the course of the study, 914 men died, including 300 who died from heart disease.

Compared with men whose fitness declined, men who maintained their fitness had a 30 percent lower risk of dying from any cause, and a 28 percent lower risk of dying from heart disease during the study.

Men who improved their fitness had a 40 percent lower risk of dying from any cause.

For every one-point improvement in fitness, as measured by the MET, men were 15 percent less likely to die from any cause, and 19 percent less likely to die from heart disease. The risk was lower even after the impact of weight changes - both losses and gains - were accounted for.

By comparison, each one-unit gain in BMI was associated with a higher risk of death, but after the effect of changes in MET was taken into account, it was no longer clear that the link was genuine.

How reliable is the research?

This study has several strengths. It was large and looked at changes in weight and physical fitness over time and in a wide age range. It also used an objective test to measure physical fitness and the intensity of the exercise the men were able to take part in.

The researchers also took into account multiple factors that might have affected how long people lived, including lifestyle factors (such as whether they smoked) and medical conditions. They also excluded people who died within the first three years of follow-up, as they may have had an undetected illness. Even so, the researchers can’t entirely rule out the possibility that some people had a decrease in fitness because they were in declining health, rather than vice versa.

Also, this study only looked at men, most of whom were white, middle, or upper class, and of normal weight or overweight at the study’s start. So we don’t know if the findings apply to other groups of people, such as women and people who are very overweight (obese). Also, the researchers did not take into account the men’s diet, as they did not have enough information about this.