People often argue that a person can be both fat and fit. Now, Swedish researchers claim that's not possible. They say it's even better to be “lean and unfit” than “fat and fit.”
In 2012, another team of scientists argued that overweight and obese people who were "metabolically fit" did not have a higher risk of developing heart disease or cancer than people of normal weight. Being "metabolically fit" meant not having insulin resistance, diabetes or high blood pressure. According to their criteria, about half of the study's 43,000 obese participants were fit. Their study was published in the European Heart Journal
The negative effects of low aerobic fitness are well documented. However, few studies have investigated the link between aerobic fitness and health among late adolescents. Instead, most of the research has focused on older adults.
Umeå University professor Peter Nordström wanted to know whether a high fitness level could make up for the increased risk of death caused by obesity in younger populations.
Nordström and a team of researchers collected data on 1,317,713 Swedish men. They tested the subjects' aerobic fitness by using an electrically braked cycle test. The scientists asked the men to cycle until they had to stop due to fatigue.
The participants were, on average, 18-years-old. The researchers followed the men for an average of 29 years to examine the association between aerobic fitness, obesity, and death. The scientists also collected data on the participants' physical fitness level, health conditions, socioeconomic status and causes of death.
During the follow-up period, 44, 301 participants died. Men in the highest fifth of aerobic fitness had a 48 percent lower risk of death than those in the lowest fifth of aerobic fitness. The lowest fifth was the group most associated with deaths due to suicide, alcohol and narcotics. The researchers also found a strong link between trauma-related death and low levels of aerobic fitness.
The normal weight men, regardless of their fitness level, were at a lower risk of death than the obese individuals in the highest quarter of aerobic fitness.
The study is severely limited in that it surveyed a population of young men. Thus, the findings may not apply to women or older adults. In addition, causes of premature death due to fitness and obesity are more likely to occur in people over 50-years-old. These causes of death include heart disease and cancer. It is possible for the participants to develop these diseases now, but the study is over and, therefore, won't include that data.
The observational study shows an association between obesity, regardless of fitness level, and death. It does not show causality.
Countless of studies have shown the benefits of exercise, so the researchers still suggest people should exercise regardless of weight. However, if a person exercises below their current abilities, they do not improve their fitness level. The study did not account for exercise that did not improve fitness level.
The research was published in the International Journal of Epidemiology
Sources: Study abstract from International Journal of Epidemiology
, press release
, PubMed Health